River Adur Catchment Flood Management Plan Appendices

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Environment Agency River Adur CFMP Draft Plan - Appendix B (March 2007) Contents

Contents ...... i Appendix A: Responsibilities for Flood Risk Management and Associated Activities...... 1 Appendix B: Environmental Report and Policy Appraisal Tables...... 3

Environment Agency River Adur CFMP (September 2008) i Appendix A: Responsibilities for Flood Risk Management and Associated Activities

The Department for the Environment, Food and Rural Affairs (Defra) has overall responsibility for flood risk management in England. Their aim is to reduce flood risk by:

• Discouraging inappropriate development in areas at risk from flooding. • Encourage the provision of adequate and cost effective flood warning systems. • Encourage the provision of adequate technically, environmentally and economically sound and sustainable flood defence measures.

The Government’s Foresight Programme has recently produced a report called Future Flooding, which warns that the risk of flooding will increase between 2 and 20 fold over the next 75 years. The report produced by the Office of Science and Technology has a long-term vision for the future (2030 – 2100), helping to ensure effective strategies are developed now. Sir David King, the Chief Scientific Advisor to the Government (2000 to 2007) concluded:

“continuing with existing policies is not an option – in virtually every scenario considered (for climate change), the risks grow to unacceptable levels. Secondly, the risk needs to be tackled across a broad front. However, this is unlikely to be sufficient in itself. Hard choices need to be taken – we must either invest in more sustainable approaches to flood and coastal management or learn to live with increasing flooding”.

In response to this, Defra is leading the development of a new strategy for flood and coastal erosion for the next 20 years. This programme, called “Making Space for Water” will help define and set the agenda for the Government’s future strategic approach to flood risk. Within this strategy there will be a holistic approach to the assessment of options through a strong and continuing commitment to CFMPs and SMPs within a broader planning matrix, which will include River Basin Management Plans prepared under the Water Framework Directive and Integrated Coastal Zone Management.

We take the lead role in preparing Catchment Flood Management Plans (CFMPs). We recognise that all key organisations and decision makers must work together to plan and take action to reduce flood risk. Consultation with other authorities, organisations and groups has been carried out in order that the plan can be adopted as a way forward for flood risk management in the catchment.

The development of the CFMP has been supported by a Steering Group with representatives from the following organisations:

• Adur District Council • Arun District Council • Brighton and Hove County Council • Defra • Natural England • Environment Agency • Horsham District Council • Mid Sussex District Council • Southern Water • West Sussex County Council

Consultation has also taken place with a number of other organisations including the National Farmers Union, RSPB, Sussex Downs Conservation Board, High Weald AONB, National Trust, Sussex Wildlife Trust, Highways Agency and members of the public.

Environment Agency River Adur CFMP - Appendix A (September 2008) 1 The Environment Agency’s role in flood risk management Since its formation in 1996, the Environment Agency has taken a lead role in flood risk management within England and Wales. Within this CFMP area, we also perform the role of Internal Drainage Board (IDB) with responsibility for land drainage issues.

We provide information on flood likelihood on the internet Flood Map. The map shows areas that would be affected by flooding from the rivers or the sea without defences. The flood extent shown on the Flood Map refers to Flood Zone 2 and Flood Zone 3 as defined in PPS25. A Flood Risk Assessment is required by Local Planning Authorities when a planning application is made within Flood Zones 2 and 3.

We are a statutory consultee on development plans and other aspects of development control within the land use planning system. The department of the Communities and Local Government has issued guidance in relation to flood risk and planning (PPS25), which stipulates a “risk based sequential search” for assessing development within the catchment. This guides the approach of planning authorities to land use allocation, and has a significant impact on development at both local and regional scale. It is therefore essential that the CFMP is compatible as well as supportive of this process. It should be noted that the CFMP does not replace a strategic flood risk assessment, which is a more detailed assessment of flood risk in relation to development and planning.

We are also responsible for flood warning. We provide an online Flood Warning Service for designated Flood Warning Areas in England and Wales that is automatically updated every 15 minutes. Flood warning makes an important contribution to reducing the impact of flooding and can be particularly effective where confidence in the prediction of rising river levels is high, allowing sufficient time for an effective response both by the public and emergency services. We work with Sussex Police, West Sussex Fire Brigade, Sussex Ambulance Service, West Sussex County Council, district councils, the Maritime and Coastguard Agency, and local community groups to co-ordinate responses to fluvial and coastal flooding.

Our flood defence work aims to protect people and property and improve the environment. The Environment Act 1995 and the Water Resources Act 1991 give the Environment Agency certain powers to carry out works on ‘main’ river watercourses for flood defence purposes. These powers are permissive and allow us to determine how and where work is carried out according to priority and available resources.

Environment Agency River Adur CFMP - Appendix A (September 2008) 2 Appendix B: Environmental Report and Policy Appraisal Tables

Contents

Non-Technical Summary

B1 Introduction and Background B1.1 The purpose of SEA B1.2 The Catchment Flood Management Plan B1.3 Structure of the report appendix B2 Consultation B3 Environmental Context B3.1 Policy, plan and programme review B3.2 Baseline review B3.3 Scope of the SEA and environmental objectives B4 Assessment and evaluation of environmental effects B4.1 Strategic options and appraisal process B4.2 Assessment and evaluation of impacts B4.3 Cumulative environmental effects B4.4 Mitigation and enhancement B4.5 Monitoring requirements References

List of Figures Figure B1 Preferred Policy Options for the Adur CFMP Figure B2 The location of the Adur Catchment Flood Management Plan. Figure B3 How the CFMP fits with the wider planning framework

List of Tables Table B1 Summary of consultation undertaken during the development of the CFMP Table B2 Review of policies, plans, and programmes and relevance to the CFMP Table B3 Scope of the SEA in relation to the CFMP Table B4 Definition of policy options Table B5 Summary of cumulative issues

List of Forms (Appraisal tables in Section B4.2) Form B.1 Purpose of the CFMP Form B.2 Meeting Legal Requirements Form B.3a Summary of Flood Risks Form B.3b Source-pathway-receptor table Form B.4 CFMP Policy Options Form B.5 Summary of current and future level and response to flood risk Form B.6 Appraisal of Policy Options against Policy Option Objectives Form B.7 Summary of the Losses and Gains Form B.8 Summary of the Preferred Policy Form B.9 Requirements for further policy development and appraisal Form B.10 Indicators for Monitoring, Review and Evaluation Form B.11 Signature of CFMP Project Manager

Environment Agency River Adur CFMP – Appendix B (September 2008) 3 Non-Technical Summary

We are developing the Adur Catchment Flood Management Plan (CFMP) in order to establish long-term (50 - 100 years) policies for sustainable flood risk management. Our policies are at the highest level in our hierarchy of spatial flood risk management plans and are about setting the right strategic direction so that in the future we take the best and most sustainable approach to managing flood risk to people, the environment and the economy. These policies will not set specific measures to reduce flood risk or establish how to manage flooding issues in a catchment.

Although not a legal requirement, we are undertaking strategic environmental assessment (SEA) as part of our planning process in order to demonstrate how our plan takes account of the environment and, in particular, the likely significant environmental effects of the CFMP.

The CFMP involves: ••• working with key partners and decision makers to establish long-term policies for sustainable flood risk management; • carrying out a strategic assessment of current and future flood risk from all sources (such as rivers, sewers, groundwater and the sea) within the catchment, understanding both the likelihood and consequence of flooding and the effect of current ways of reducing risk. We measure the scale of risk in social, environmental and economic terms; • considering how the catchment works, and looking at other policies, plans and programmes to identify opportunities and constraints to achieving sustainable flood risk management; • finding ways to work with nature, and manage flood risk to maintain, restore or improve natural and historic assets.

In undertaking the SEA we considered the baseline environment, and how this would evolve without the influence of our plan.

People and communities At the household and community level, flooding can cause personal distress, poor health and damage to property and possessions as well as pose a threat to life. There are currently approximately 150 residential properties and approximately 400 people at risk across the catchment under a 1% annual probability flood outline. The majority of these properties are located in the Lower Adur and Ferring Rife, including Steyning, Upper Beeding, Bramber, Shoreham and Ferring, where flooding also occurs from surface water, groundwater and sewer systems. The Lower Adur is also the catchment most sensitive to future change. In total, it is predicted that the number of properties and people at risk from a 1% annual probability flood event will rise to approximately 2,400 and 5,800 respectively in 50-100 years time. The majority of these increases are attributed to significant increases in risk in Shoreham.

Property and infrastructure The Annual Average Damages (AAD) to property and agricultural land currently total approximately £5 million under a 1% annual probability flood outline and £0.3 million for more frequent flooding (10% annual probability). The majority of these damages are sustained in the Lower Adur and Ferring Rife catchments due to the large number of residential and commercial properties at risk in the towns of Steyning, Upper Beeding, Bramber, Ferring and Worthing. The low damage values in the Adur West Branch sub-catchment result from the rural and sparsely populated nature of the area. The damages in this area constitute the highest agricultural costs in the catchment. There are also currently 1 sewage treatment works and approximately 2km of main road under threat in the 1% annual probability flood outline and approximately 1.4km

Environment Agency River Adur CFMP – Appendix B (September 2008) 4 under the 10% annual probability flood outline. In 50-100 years, total AAD to properties and agricultural land are predicted to have increased to approximately £15 million, the length of main road affected to have increased to approximately 10km and a number of emergency services and hospitals become exposed to flood risk (1% annual probability). Properties and major transport routes in Brighton and Hove have flooded from groundwater and surface water in the past. The most recent widespread flooding in Brighton and Hove was during 2000. There are also likely to be a number of properties at risk from the Teville Stream, however current information on this watercourse is limited.

The environment In terms of the environment, there are currently approximately 5km2 of proposed National Park, approximately 1.5km2 of Environmentally Sensitive Area (ESA) and approximately 1.5km2 of Area of Outstanding Natural Beauty (AONB) at risk from a 1% annual probability flood outline. There are also 0.6km2 of Adur Estuary Site of Special Scientific Interest (SSSI), 3.5km2 of Sites of Nature Conservation Importance (SNCI) including the River Adur Water Meadows, Wyckham Wood and Ferring Rife and Meadows (1% annual probability). In 50-100 years, these areas are not expected to have expanded significantly. There is a degree of tourism and recreation value associated with these sites. There are also issues of soil erosion and surface water run-off that cause a significant problem to the environment and in terms of depositing ‘muddy’ flooding to properties in Worthing and Brighton and Hove which are downstream of the South Downs. There are also water quality issues associated with this which have the potential to cause problems within designated sites. There is significant potential within this catchment to restore geomorphological processes to reduce these problems as well as flood risk in general.

Our understanding of the likely future of the catchment is based upon various scenarios from our broad-scale modelling, where estimated changes to the climate, development and land management could result in changes to flood risk. We used these scenarios to understand what six generic policy options could mean for flood risk to people, the environment and the economy. The options we considered were:

1. No active intervention (including flood warning and maintenance). Continue to monitor and advise 2. Reduce existing flood risk management actions (accepting that flood risk will increase over time) 3. Continue with existing or alternative actions to manage flood risk at the current level (accepting that flood risk will increase over time from this baseline) 4. Take further action to sustain current scale of flood risk into the future (responding to the potential increases in flood risk from urban development, land use change, and Climate Change). 5. Take further action to reduce flood risk (now and/or in the future) 6. Take action to increase the frequency of flooding to deliver benefits locally or elsewhere, (which may constitute an overall flood risk reduction, for example for habitat inundation).

With our Steering Group we established a series of social, environmental and economic objectives for the catchment that drew from other policies, plans and programmes.

Economic • Ensure that river channel and flood defence maintenance expenditure is appropriate to the economic damage of flooding. • Ensure flood damages do not significantly increase in the future (for example due to climate change).

Social • Ensure the impact of flooding on people and properties does not significantly increase in the future (for example due to climate change). • Ensure the disruption caused by flooding to transport and critical infrastructure does not significantly increase in the future (for example due to climate change). • Reduce the impact of muddy flooding.

Environment Agency River Adur CFMP – Appendix B (September 2008) 5 Environmental • Protect and enhance nationally and internationally important species and habitats. • Restore rivers and floodplains to a naturally functioning state where feasible.

These objectives establish the key aims of the CFMP. We also consulted with the public on our draft objectives, and it was against these that we appraised the alternative policy options, drawing from opportunities and constraints provided from other policies, plans and programme. The most important opportunities and constraints to our CFMP are as follows:

Opportunities: • Enhance the character of the landscape and increase amenity opportunities for recreation, tourism and leisure activities. • Help meet national biodiversity action plan (BAP) targets. • Work with the High Weald AONB Joint Advisory Committee to achieve the targets set in the High Weald AONB Management Plan to maximise the opportunities for natural processes to reduce flooding through the adoption of river restoration policies, whilst enhancing landscape character. • Move toward more natural rivers and drainage networks, as outlined within PPS25, will mean we can achieve more efficient and sustainable water management, whilst enhancing landscape character. • Investigate removal of Environment Agency owned and maintained existing raised defences to reinstate the floodplain between Partridge Green and Steyning and between Steyning and Shoreham to a naturally functioning state, to provide flood storage and enhance conservation value and biodiversity. • Influence the coastal defence strategy, along the Lower Adur, Teville Stream and Ferring Rife, to improve the sustainability of flood risk management in the this area. • Provide development control advice to ensure no increase in run-off from the new development proposed in the South East Plan (e.g. Brighton and Hove, Worthing, Shoreham and Burgess Hill). • Reduce flood risk and improve water quality by promoting and encourage the use of SuDS in the proposed urban developments in Brighton and Hove, Worthing, Shoreham and Burgess Hill. • Investigate the feasibility of incorporating the Teville Stream into the Floodline Warnings Direct service by installing new level gauges on the Teville stream. • Continue local authority and Environment Agency support of the Flood 1 project in relation to groundwater flooding. • Develop a flood warning system for groundwater flooding. • Continued practice and development of the Emergency Response Plan in Brighton and Hove, Worthing, Shoreham, and Burgess Hill. • Reduce surface water run-off and soil erosion by supporting the existing and future management policies regarding environmentally sensitive farming practices (e.g. those set out by Brighton and Hove City Council). • Support the existing flood defence measures in relation to surface water flooding, such as bunds provided by Brighton and Hove City Council. • Potential for improving the current defences, for example possible installation of demountable or temporary defences in Shoreham and Burgess Hill. • Improvements in the efficiency of channel and flood defence maintenance processes. • Effective and efficient use of developer contributions for flood risk management. • To work with Defra/ farmers to produce soil management plans which have a benefit to flood risk through reducing the run-off rate.

Constraints: • Government and international legislation, environmental management policies, plans and strategies for the catchment must be complied with, such as

Environment Agency River Adur CFMP – Appendix B (September 2008) 6 accommodating new housing within the catchment as detailed by the South East Plan and compliance with the Habitats Directive. • Existing urban development may prevent reinstatement of natural river processes. • Individual homes and properties are currently at risk of flooding. • Transport links in the catchment are a vital part of the communication network regionally, nationally and internationally, in particular the railways connecting London to the south coast and connecting the coastal towns and cities, the A23, A24, A27, A259, A283 and A2032. • Some environmentally designated habitats are susceptible to changes in flood frequency, floodwater chemistry, groundwater levels and drainage system maintenance. • Historic development and some heritage designations in Steyning, Bramber and Upper Beeding present permanent physical obstructions. • Presence of protected species with specific water level, water quality and habitat requirements, for example in the Adur Estuary SSSI. • Location of electricity pylons adjacent to the Lower River Adur (currently protected by existing defences). • No degradation of existing fish passage and habitat. • Visual impact of flood risk management activities within the proposed National Park or Areas of Outstanding Natural Beauty. • Steep catchments of the South Downs result in rapid run-off and quick responses to rainfall events. • A suitable level of productivity from agricultural land needs to be retained. • Changes to flood risk management can affect the landscape, its character and value as an amenity. • CFMP objectives and policies must complement those of the Shoreline Management Plan (SMP) that affects the CFMP area. • Available funding for the initial set up of new flood risk management schemes. • Older flood defence structures are likely to be costly to maintain. • Limited available information on surface water and groundwater flood damages.

Having established the catchment objectives, and identified the opportunities and constraints for the CFMP, all the relevant information gained about the catchment was brought together in order to divide the CFMP area into similar areas, using the following criteria:

• Current level of flood risk; • Hydraulic characteristics and flood mechanisms; • Topography, geology and drainage characteristics; • Land use land use and drivers for change; • Links to other plans; and, • Opportunities for future flood risk management.

From this, the River Adur catchment was divided into 9 separate policy units. Each policy unit was then assessed to decide which policy would provide the most appropriate level and direction of flood risk management for both now and the future. One of six standard flood risk management policies, listed on page 4, has been applied to each policy unit. These policies have been agreed nationally and are being applied to CFMPs in a standard way across England and Wales. Our preferred policies are as follows:

Environment Agency River Adur CFMP – Appendix B (September 2008) 7 Figure B1 Preferred Policy Options for the Adur CFMP

The significant impacts likely to result from implementing the CFMP policies are as follows:

• Annual Average Damages (AAD) caused by flooding are unlikely to increase significantly in the future, particularly in the urban areas of Shoreham, Burgess Hill and Hassocks, where flood defences are set to be improved in order to prevent increased flood risk due to climate change. The combination of flood attenuation in the Adur catchment and South Downs with maintained flood defences in Worthing, Brighton, Hove, Steyning and Upper Beeding will also prevent a significant increase in flood damages. • The balance of flood risk management (FRM) to AAD will be efficient across the catchment. • The impact of flooding on people and properties will be prevented from significant increases across the catchment. • The level of disruption to critical infrastructure and transport routes will not increase in the future. • Rivers and floodplains will be restored to a more natural state throughout the Adur catchment and Upper Adur. This will also result in increased wetland habitat areas.

Environment Agency River Adur CFMP – Appendix B (September 2008) 8 • The CFMP is likely to have a positive impact on the biodiversity of the catchment, especially those habitats and species dependant upon the water environment. These areas will be protected and also extended and enhanced. • Sustainable land management practices are likely to increase in uptake and efficacy resulting in reductions in water run-off rates and soil erosion. This in turn will reduce the likelihood of muddy flooding in urban areas downstream of the South Downs.

These preferred policies have been selected because alternative options would have resulted in a less sustainable and coordinated approach to flood risk management or unnecessary environmental impacts on a catchment level. These policy options have been chosen within the limits of the aforementioned constraints whilst maximising the potential to alleviate flood risk and benefit the environment.

The strategy of this CFMP is to increase water retention and storage capacity in the sparsely populated upper catchment and River Adur channel and floodplain while increasing defences around high-risk urban areas, particularly Burgess Hill, Hassocks and Shoreham which will benefit from increased defences in line with future change in flood risk due to climate change and sea level rise. The towns of Steyning, Upper Beeding, Brighton, Hove and Worthing will also benefit from the combined effects of maintaining current FRM and attenuating flood risk upstream. In particular appropriate land management practices on the South Downs have potential to reduce muddy flooding in both Worthing and Brighton and Hove. This strategy will help to achieve the key objectives of the CFMP by ensuring the number of people and properties at risk from flooding will not increase significantly in the future. This will also ensure the disruption caused by flooding of critical infrastructure and transport routes does not increase. AAD incurred through flooding to properties and agricultural land will in turn be prevented from significant increases in the future and may even be reduced in parts of the catchment.

Studies will be completed where understanding of current and future flood risk from rivers, groundwater, surface water and urban drainage is less developed, such for the Teville Stream and Brighton and Hove. This will enable better informed decision making.

Returning the River Adur and its floodplain to a more natural state will have significant environmental benefits. Habitats and species will be protected and designated sites enhanced in accordance with UK and local BAP targets and water-dependent SSSIs will be improved towards the Public Service Agreement to bring 95% of SSSI land into ‘favourable’ condition by 2010. SNCIs will also benefit from increased frequency of flooding in managed and predictable way. With careful management, these improvements may lead to increased amenity and recreation value throughout the CFMP area. These important benefits will not be maximised unless the naturalisation of the River Adur is carried out in a managed and predicable way. A ‘do nothing’ approach may result in damage to sensitive environmental sites.

Increasing water retention and storage capacity in both the Adur catchment and South Downs will serve to alleviate flows and the frequency, depth and extent of flooding further downstream in high-risk urban areas. This process will also have to be managed to protect and enhance wherever possible habitat and species diversity and landscape character. This CFMP also supports the uptake of environmentally beneficial land management practices which will form part of an integrated FRM strategy and greatly reduce run-off rates and soil erosion in the agricultural areas of catchment. These schemes will also lead to shifts in land use practices that will enhance biodiversity.

By taking a proactive approach in all parts of the catchment, this CFMP will support the implementation of sustainable planning policies and feed into ongoing planning processes and document revisions. This will lead to the development of a more integrated and environmentally, socially and economically sustainable flood risk management strategy.

Environment Agency River Adur CFMP – Appendix B (September 2008) 9 Our mitigation and enhancement measures are included within the appraisal of alternative policy options; and will be cascaded down through our subsequent and more detailed plans as we decide the flood risk management measures we need to implement the policies. The monitoring of the significant effects of the plan will include (in no particular order): a) Change in AAD to properties (£); b) Change in AAD to agricultural land (£); c) Change in estimated damages resulting from surface water flooding (£) d) Change in number of people affected by 1% annual probability flood outline; e) Change in estimated number of properties affected by surface water and/or groundwater flooding; f) Change in the estimated number of properties affected by downland ‘muddy’ surface water flooding; g) Change in length of main roads affected by 1% annual probability flood outline (km); h) Change in number of critical infrastructure sites affected by the 1% annual probability fluvial flood event; i) Change in the number and period of recorded A road and railway closures due to surface water flooding; j) Change in the number if critical infrastructure sites recorded as being affected by surface water flooding; k) Change in balance of annual river channel and flood defence maintenance (£) to annual average damages from fluvial flooding to agriculture (£); l) Change in area of naturally active floodplain restored (km2); m) Change in length of naturally functioning river (km); n) Achievement of BAP targets and improved habitat quality and species diversity; and o) Change in landscape character assessment of the AONB, ESA and/or proposed National Park.

These indicators are monitored by various agencies best placed to do so as part of their internal targets monitoring. This information is largely collected in a standardised way on a relatively regular basis. These indicators are therefore practical and feasible measures to monitor the progress of the CFMP over the following years. In doing so, unforeseen adverse effects on the environment and/or communities within the catchment will be identified and the necessary remedial actions taken.

The Environment Agency will look to work with local authorities to monitor indicators a) to k). The Environment Agency is likely to be best placed to monitor indicators l) to o) as lead partners in Local Biodiversity Partnerships, or as participants in monitoring systems such as the English Nature Site Information Service (ENSIS) and the Biodiversity Action Reporting System (BARS), both maintained by Natural England. Natural England will also be a useful resource for most of the environmental information needed to effectively monitor this CFMP.

Environment Agency River Adur CFMP – Appendix B (September 2008) 10 B1 Introduction and Background

B1.1 The purpose of SEA This appendix documents the strategic environmental assessment (SEA) process undertaken for the Adur Catchment Flood Management Plan (CFMP).

Strategic environmental assessment is a systematic process for anticipating and evaluating the environmental consequences of plans and programmes prior to decisions being made. The purpose of SEA is to provide for a high level of protection of the environment and to contribute to the integration of environmental considerations into the preparation and adoption of plans and programmes with a view to promoting sustainable development. There is no legal requirement for us to undertake SEA for CFMPs because they are not required by legislation, regulation or administrative provision. However they clearly help set the framework for future planning decision, and have the potential to result in significant environmental effects. As a result Defra guidance (Defra, September 20041) and our own internal policy have identified a need to undertake a SEA approach.

In developing our CFMP, we consider the environment alongside social and economic issues. This appendix demonstrates how we have gone about undertaking the SEA for our CFMP. The contents of this Environmental Report have been broadened to include the social and economic effects also considered in our plan making process.

1 http://www.defra.gov.uk/environ/fcd/policy/sea.htm

Environment Agency River Adur CFMP – Appendix B (September 2008) 11 B1.2 The Catchment Flood Management Plan

Figure B2 shows the location of the Adur CFMP with the various policy units identified.

Figure B2 Location of Adur Catchment Flood Management Plan

CFMPs are planning documents that we are preparing for all surface water river catchments across England and Wales. In developing the CFMPs, we are working with other key decision- makers to help us to establish policies to manage flood risk for the next 50-100 years. We know we cannot reduce flood risk everywhere, so we need to target efforts to where they are needed most: this is the purpose of our CFMP. They will not set specific measures to reduce flood risk or establish how to manage flooding issues in a catchment. Our policies are at the highest level in our hierarchy of spatial flood risk management plans and are about setting the right strategic direction so that we take the best and most sustainable approach in the future. To do this, we need to understand the extent, nature and scale of current and future flood risk to people, the environment and the economy across the whole catchment before choosing certain policies.

Environment Agency River Adur CFMP – Appendix B (September 2008) 12 We need to decide at this stage where to take further action to reduce or sustain flood risk, where we need to change the way we currently manage flood risk, or where we need to take little or no action.

The main body of the CFMP report provides a more detailed introduction to the CFMP, including the contents, aims and objectives of the plan: see Section 1.1 (Background) and Section 1.2 (Aims and Scope).

The CFMP involves: • carrying out a strategic assessment of current and future flood risk from all sources (such as rivers, sewers, groundwater and the sea) within the catchment, understanding both the likelihood and consequence of flooding and the effect of current ways of reducing risk. We measure the scale of risk in social, environmental and economic terms; • identifying opportunities and constraints within the catchment to reduce flood risk through changes in land use, land management practices and/or the flood defence infrastructure; • finding ways to work with nature, and manage flood risk to maintain, restore or improve natural and historic assets; • working out priorities for studies or projects to manage flood risk within the catchment, and identifying responsibilities for the Environment Agency, other operating authorities, local authorities, water companies or other key interested groups.

B1.3 Structure of the report appendix

This appendix documents the SEA process we have undertaken throughout our CFMP planning process and covers:

• B2 – Consultation: setting out information on how we have engaged interested parties, including the SEA consultation bodies, through CFMP development and the SEA process. • B3 – Environmental Context: The relationship between the CFMP and relevant plans and programmes; a summary of the relevant environmental baseline in the catchment. It also sets out the environmental issues scoped into the SEA process and the environmental objectives used to carry out the assessment in Section B4. • B4 – Assessment and Evaluation of Environmental Effects: Setting out the environmental effects of the different options available to the CFMP, cumulative effects of the CFMP as a whole and with other relevant plans in the catchment. It also sets out how mitigation and enhancement are considered at this strategic scale and the future monitoring requirements.

Note: hyperlinks have been provided to the main report to allow the reader to appreciate the broader context of our plan-making process.

Environment Agency River Adur CFMP – Appendix B (September 2008) 13 B2 Consultation

Section 1.5 Involving others in the main CFMP report provides information about the consultation undertaken to date. This information is repeated below.

The aim of consultation during the CFMP process is to obtain feedback and build consensus with the Consultation Group on issues identified during the catchment understanding process, and the proposed adoption of certain policies in certain areas of the catchment. Consultation includes statutory and non-statutory consultation bodies and is integral to the process at every stage in addition to defined periods.

Developing a CFMP takes a considerable amount of time, and allows for public consultation so that people can be informed of the process and what is being achieved. It enables comments and suggestions on the plan to be received. Table B1 below, shows how we gathered information and consulted and worked with important groups and organisations for this CFMP.

The draft CFMP report and the previous inception and scoping reports are available on our website2. This report is at the draft main stage and will be updated after this consultation period. Now is the opportunity for you to give your feedback and input on all parts of the report before it is finalised.

The Consultation Group for this CFMP has included a wide range of statutory, non-statutory, environmental and socio-economic interest groups as well as members of the general public. These groups have participated at each key stage of the CFMP to date and their opinions and suggestions have been incorporated throughout, wherever feasible and appropriate.

The Steering Group is a wider group brought together to guide the technical delivery of a CFMP, to focus the data collection, and to sign off the various reports produced prior to their publication. The Steering Group is comprised of key Environment Agency staff and staff from other major stakeholders including:

• Adur District Council; • Arun District Council; • Brighton and Hove City Council; • Defra; • Environment Agency; • Horsham District Council; • Mid Sussex District Council; • Natural England; • Southern Water; • West Sussex County Council; and, • Worthing Borough Council.

Key stakeholders in the catchment comprise statutory and non-statutory agencies and groups as well as members of the public. Those who were consulted during the CFMP process include, but are not limited to, the following:

• Campaign to Protect Rural England; • Country Land And Business Association; • Natural England;

2 http://environment.gov.uk/regions/southern/290158/954666/995532/1493581/?version=1&lang=_e

Environment Agency River Adur CFMP – Appendix B (September 2008) 14 • English Heritage; • Farming and Wildlife Advisory Group; • Forestry Commission; • Highways Agency; • National Farmers Union; • National Trust; • Network Rail; • Parish Councils (various); • Ramblers Association; • Royal Society for the Protection of Birds; • South Downs Joint Committee; • Sussex Otters and Rivers Partnership; and, • Sussex Wildlife Trust.

Table B1 Summary of consultation undertaken during the development of the CFMP

CFMP timetable CFMP stage When Actions Achievements Inception reports issued All Sussex CFMP Reports Inception Stage January 2004 according to CFMP rolling delivered. programme. October 2005 Scoping stage started. Further development of catchment understanding and January 2006 Scoping workshop held. review of hydraulic model output. Scoping Stage Scoping Report public consultation period. Report available on Environment April 2006 to Comments on all aspects of Agency website, main June 2006 the Scoping Report received. libraries and advertised in local newspapers.

July 2006 Draft main stage started. Review of policy unit September boundaries and application of Steering Group meeting held. 2006 flood risk management policies. Public consultation period. Comments on all aspects of June 2007 to Draft CFMP available on the draft CFMP, notably: September Environment Agency website, Main Stage Policy choice 2007 main libraries and advertised Action plan. in local newspapers. November Review of consultation Steering Group meeting. 2007 responses and finalise CFMP. Available on the Environment September Agency’s website with hard Final CFMP published. 2008 copies in selected libraries and local authority offices.

Scoping Report consultation summary Responses were received by Mid Sussex District Council and West Sussex County Council. Below is a summary of the main environmental, social and economic issues that have been highlighted during the Scoping Stage consultation period and throughout the CFMP process which have been incorporated into the CFMP where feasible and appropriate:

Environment Agency River Adur CFMP – Appendix B (September 2008) 15

• Concern over how an integrated drainage strategy will be implemented, and by who (Mid Sussex District Council); • Expressed need for appreciation of careful management requirements where areas of the catchment have been identified for Policy 6 (West Sussex County Council); • Queries as to how the CFMP will promote agri-environment schemes (West Sussex County Council); and, • The consequences associated with an increased frequency of flooding in the Adur Valley in terms of increased tidal vulnerability should be assessed in greater detail (West Sussex County Council).

Draft CFMP Report consultation summary During the three-month consultation period, formal responses were received from Mid Sussex District Council, Henfield Parish Council, West Sussex County Council, Brighton and Hove City Council and Burgess Hill Town Council. The majority of the comments either requested clarification, revisions or greater detail, or offered further information about flood risk and management in their areas. These points were considered and the report amended as appropriate.

West Sussex County Council appreciated the recognition that FRM is a major contributor to sustainable development and supported the implementation of policy option 6 across stretches of the Adur, whilst cautioning the need for careful management. The Council also recognises that it is important that the CFMP support landowners and farmers wishing to enter agri- environment schemes but is concerned the CFMP does not address how this will be achieved and that Natural England should be involved with this. As Natural England is a statutory consultee and member of the Steering Group for this CFMP, the organisation is involved throughout the development of the CFMP. There is a good framework in place to extend this involvement in to the implementation phase of the CFMP. Similarly, the Council highlight the work of the Sussex Water Partnership and its potential role in implementing sustainable water management. The Environment Agency will endeavour to work with appropriate stakeholders to implement the CFMP. The Council also commented on the need to identify appropriate locations and mechanisms for implementation of wetland recreation and expansion. The Council also highlighted the potentially positive effects of flooding on sites of historical interest, namely Bramber and Knepp Castles.

Henfield Parish Council reiterated the view that current floodplains must be properly maintained to reduce the risk of flooding in the future. There is indeed large scope for river and floodplain restoration within this catchment and this is integral to the strategy of this CFMP in minimising flood risk.

Burgess Hill Town Council welcomed the policies and action plan set out for the policy unit of Burgess Hill and Hassocks and also encouraged a system that would allow documents produced by different stakeholders to be reviewed regularly to ensure that the impact of any changes in one document is taken into account in the strategies of others. This is an approach that is very much welcomed and encouraged by the CFMP. Every effort has been made to identify the synergies, opportunities and constraints between plans, policies and programmes as reviewed in Tables B2 and B5 below.

Environment Agency River Adur CFMP – Appendix B (September 2008) 16 B3 Environmental context

B3.1 Policy, plan and programme review

The SEA considers the relationship between the CFMP and other relevant plans and programmes. A review was undertaken at the scoping stage and updated during the main stage assessment, in order to:

• help collate additional environmental baseline information for developing the CFMP; • identify environmental issues relevant to the SEA (e.g. existing environmental problems / protection objectives); • identify influences of the CFMP on existing plans and programmes and vice versa; • understand these relationships to help evaluate the significance of environmental effects; • help identify any further assessment required.

A diagram setting out our view of the relationship between CFMPs and other key policies, plans and programmes is illustrated in Figure B2. Section 1.4 Links with other plans discusses the relationship with other plans. Those plans that we have drawn into the development of the CFMP are listed in Table B3.

Figure B3 How the CFMP fits with the wider planning framework

Environment Agency River Adur CFMP – Appendix B (September 2008) 17 Table B2 Review of policies, plans, and programmes and relevance to the CFMP Relevant plan, policy or programme Potential influence Relevant opportunities or constraints we need the CFMP to consider Land-Use Planning (Regional and Local Government) Regional Spatial Strategy for South East (March Water utility efficiency (now and in the future) will Reducing risk to critical infrastructure, material 2006) influence water resources, aim to stabilise and reduce assets, people and property. footprint. Exposure to flood risk (now/future) to Improving water resource efficiency and quality. developments depending on housing allocations, new Extent of tree cover and green open spaces now and improved strategic infrastructure, tree cover/open and in the future and the impact of this on run off, spaces. storage and flow patterns. Brighton and Hove Local Plan 2001 Managing risks to reduce the threat to people and their Potential to aid future developments to meet property sufficient environmental requirements Enforcing adequate protection measures for essential CFMP should ensure sufficient infrastructure is in water resources. place including land drainage, coastal defence and Influence on new developments in areas at risk from flood-prevention structures prior to development. flooding. Aiding planning and development in the Coastal Zone. Adur District Plan 1996 Protection of existing water resources and sustainable Opportunity to strictly control development in the water management. countryside in undeveloped areas between Development in areas exposed to flood risk. Worthing and Lancing/Sompting and Shoreham-by- Protection of all designated and other areas of national Sea. and local nature conservation importance. Potential to restrict development encroaching on the South Downs. Potential to influence planning permission in flood risk areas. Protection of integrity of coastal and flood defences. Protection of SSSIs – the Adur Estuary at Shoreham-by-Sea and Cissbury Ring and Local Nature Reserves at Lancing Ring in Adur District and Mill Hill in Shoreham-by-Sea. Horsham District Local Plan 1997 Development in areas exposed to flood risk Protection and continued conservation of Sussex (now/future). Downs and High Weald AONBs. Protection of AONB and SSSIs. Restrictions on planning permission in areas associated with flood risk. Worthing Local Plan 2003 Enhancing and protecting local nature sites. Accommodating proposed development at Future Development. Durrington and East Worthing. Water resource management. Opportunity to aid the implementation of the coastal

Environment Agency River Adur CFMP – Appendix B (September 2008) 18 Relevant plan, policy or programme Potential influence Relevant opportunities or constraints we need the CFMP to consider Development in the coastal zone. defence strategy. Coastal and tidal flooding defences. Mid Sussex Local Plan 2004 Strong protection of AONBs from development- Accommodating future development around defining ‘built-up’ boundaries. Haywards Heath and Burgess Hill. Preservation of buildings of architectural or historic Reducing risk to assets and character of interest and their settings, archaeological sites and settlements such as Haywards Heath. their settings, and preservation and enhancement of Potential to develop better land use planning in the special character and appearance of conservation. future taking into account water resources, use and extraction. Flood Risk Management Planning Beachy Head to Selsey Bill Shoreline Policy framework addressing flood risk to people and CFMP objectives must complement those of the Management Plan (First Review) the historic and natural environment located at the SMP. coastline. Maintenance and upgrade of existing shoreline and Management of coastal defences coastal defences at Shoreham Harbour Protection of biodiversity. Maintenance of existing river walls and embankments on the mouth of the River Adur and upgrading them as sea levels rise. CFMP must complement ‘hold the line policy’ along relevant coastline to maintain protection from coastal erosion and flooding. Other Water Management Planning Adur and Ouse Catchment Abstraction Sustainable management of water resources in the Addressing quality concerns associated with the Management Plan (March 2005) catchment including water allocation and abstraction large Goddards Green waste water treatment licensing. works discharges to the Eastern branch of the River Adur. Improving water resource efficiency and abstraction issues. River Basin Management Plans Plans to achieve Water Framework Directive targets Maintenance of water quality status of water bodies for 2015. River Basin characteristics, review of impact in the CFMP area and opportunities for improving of human activity on status of water bodies and an towards Water Framework Directive targets. economic analysis of water use. Impact of improving water quality on flow, erosion, sedimentation and water body capacity. Opportunities for protecting and enhancing biodiversity, UK and local BAP priority species and habitats and designated fisheries. Directing the Flow – Priorities for future water Future water policy to respect environmental limits, Potential opportunities for identifying water pollution

Environment Agency River Adur CFMP – Appendix B (September 2008) 19 Relevant plan, policy or programme Potential influence Relevant opportunities or constraints we need the CFMP to consider policy (November 2002) productivity, abstraction, health, pollution, land use issues arising from agricultural and urban diffuse planning, climate change and recreation in order to pollution. implement the Water Frameworks Directive. Opportunity for improved understanding of the catchment and better land use planning in the future, taking into account varying characteristics across the catchment, including water quality, water demand and land use. Potential for complementary land use management policies to reduce soil erosion and surface water run off. Potential opportunities for returning watercourses to a more natural state. Making Space for Water - Urban flood risk and An holistic approach taking account of all sources of The CFMP must comply with management policies integrated drainage (March 2005) flooding, reflecting other relevant to address flood risk and coastal erosion. Government policies in the policies of flood and Opportunities to assess and improve the coastal erosion risk management. effectiveness of current flood risk management The aim will be to choose options that manage risks to responsibilities and arrangements. reduce the threat to people and their property and Potential to identify opportunities for land use deliver the greatest environmental, social and planning to encourage sustainable urban drainage. economic benefit consistent with the principles of sustainable development.

Rural Land Management Planning Land Use Management Plans and Polices, Holistic land use management plans and schemes Although limited information is currently available including Common Agricultural Policy (CAP), promoting increased environmental protection. on how changes in land management influences Single Payment Scheme (SPS), Environmental Farmers must maintain their land in good agricultural flood flows at a catchment level, it is known that Stewardship (ES), and England Rural and environmental condition. Schemes also promote they do affect run-off at the plot level and therefore Development Plan (ERDP) organic farming, energy crops, and increased may be an important influence on the risk of woodland cover. There is likely to be a shift towards flooding. These agri-environment schemes may these schemes in the future, potentially reducing flood have an effect on CFMP objectives and also risk through sustainable land management practices. incorporate additional opportunities and constraints In the South East region, more woodland planting may such as conservation of wildlife (biodiversity), occur and it is unlikely horticulture will expand so maintenance and enhancement of landscape pesticide use and pressure on water resources should quality and character, protection of the historic reduce. environment and natural resources. Regional Forestry and Woodlands Framework for Framework to protect trees, particularly ancient ones, Tree planning targets can potentially help reduce the South East from loss and to bring woodland habitat back into good downstream flows (and do help us meet our flood

Environment Agency River Adur CFMP – Appendix B (September 2008) 20 Relevant plan, policy or programme Potential influence Relevant opportunities or constraints we need the CFMP to consider ecological condition while increasing their amenity risk management objectives). Soft engineering value, potential for carbon sequestration and solutions, such as river bank stabilisation, would be preservation of archaeological heritage. Also included supported under this framework. However, a are provisions for wet woodland restoration and river possible constraint would be the protection of trees bank stabilisation. and woodlands from flood risk. This landscape scale approach to management would provide considerable scope for integrating objectives. High Wealds AONB Management Plan Maintenance and enhancement of landscape Landscape character must be retained in general character. and particularly in AONBs. Restoration of natural function of river catchments. Opportunity for CFMP to reduce flood risk through Protection of sandstone outcrops. restoration and protection of functional floodplains. Opportunity to improve public understanding and awareness of the benefits of river restoration. Protection and enhancement of UK and local BAP priority species and habitats (wetlands, wet woodlands and riverine habitats). Consideration of CFMP policy options’ impact on sandstone outcrops. South Downs Management Plan (October 2007) Policies to reduce stress from abstraction, mitigate Opportunity to improve river flow and reduce flood rising water demand, prevent drying of chalk streams risk where areas may be vulnerable to flooding, or and low flows, reduce soil erosion and water pollution increase inundation for water compatible sites and mitigate increasing flood severity and frequency. through floodplain and wetland restoration and maintenance of water flow to ditches. Consider threats of pollution to surface and groundwater due to flooding events. Consider future constraints of National Park status of Sussex Downs AONB. Alleviate abstraction pressure through increased storage elsewhere in the catchment. Other Relevant Plans UK Biodiversity Action Plan (BAP) and Local BAP Priority habitats found in the catchment are coastal Presence of protected species with specific water for Sussex and floodplain grazing marsh, saltmarsh, chalk level, water quality and habitat requirements must grassland, heathland and several other habitats. be considered. Some environmentally designated Priority species include water voles, European otters habitats are susceptible to changes in flood and great crested newts. Fish species included are frequency, floodwater chemistry, groundwater lamprey, European eel and brown/sea trout (the latter levels and drainage system maintenance. It is two of which have been added to the UK BAP list in imperative that priority habitats and species are

Environment Agency River Adur CFMP – Appendix B (September 2008) 21 Relevant plan, policy or programme Potential influence Relevant opportunities or constraints we need the CFMP to consider 2007). maintained and enhanced by preventing loss and damage to existing habitat, promoting new areas of habitat and improving quality through appropriate flood risk management activities. Local Environment Agency Plan (LEAP) LEAP’s are a holistic approach to environmental There is significant potential within the CFMP to management allowing the full range of management protect, improve and enhance habitat species issues to be identified and considered within a diversity and therefore comply with and help geographical area, which is both relevant and towards BAP targets. The LEAP has considered meaningful. LEAP’s are seen as the key mechanism the potential contribution of riverine systems and for prioritising actions arising from biodiversity action habitats within the BAP framework and this will be plans. considered as an objective in the CFMP. South East England Regional Assembly – Objective to utilise and husband the region’s numerous There are opportunities within the CFMP process to Destination South East Proposed Alterations to environmental assets to foster sustainable tourism. contribute to the aims of this plan. For example, the Regional Planning Guidance, South East, Protecting access to and support proposals for restoration of wetlands and river corridors will Tourism and Related Sport and Recreation (May upgrading inland waterways and associated facilities increase the amenity value and tourism and 2003) for recreational use in accordance with relevant recreation potential within the catchment. Efforts management strategies. should be made to avoid disruption to existing Avoid loss of waterside sites to uses that do not recreation facilities through implementation of require deep-water access. There is also a strategic CFMP policies. focus on the coastal strip of the South East.

Environment Agency River Adur CFMP – Appendix B (September 2008) 22 B3.2 Baseline review

Section 2 Catchment overview provides an overview to the characteristics of the catchment, including the environmental aspects relevant to the CFMP. Environmental issues within the catchment relevant to this CFMP are summarised below. Section B4. Assessment and evaluation of environmental effects provides more detail of the environmental characteristics of the individual areas most likely to be affected by the plan, their current state of the environment and the likely evolution thereof without implementation of the plan.

Property and infrastructure The AAD to property and agricultural land currently total approximately £5 million under a 1% annual probability flood outline and £0.3 million for more frequent flooding (10% annual probability). The majority of these damages are sustained in the Lower Adur and Ferring Rife catchments due to the large number of residential and commercial properties at risk in the towns of Steyning, Upper Beeding, Bramber, Ferring and Worthing. The low damage values in the Adur West Branch sub-catchment result from the rural and sparsely populated nature of the area. The damages in this area constitute the highest agricultural costs in the catchment. There are also currently 1 sewage treatment works and approximately 2km of main road under threat in the 1% annual probability flood outline and approximately 1.4km under the 10% annual probability flood outline. In 50-100 years, total AAD to properties and agricultural land are predicted to have increased to approximately £15 million, the length of main road affected to have increased to approximately 10km and a number of emergency services and hospitals become exposed to flood risk (1% annual probability). Numerous properties are at risk from surface water, groundwater and urban drainage flooding, particularly in Worthing and Brighton and Hove. Transport routes including the A23 and railway lines are also at risk of flooding.

Environment Agency River Adur CFMP – Appendix B (September 2008) 23 problems within designated sites. There is significant potential within this catchment to restore geomorphological processes to reduce these problems as well as flood risk in general.

B3.3 Scope of the SEA and environmental objectives

An important early stage in the SEA process is to identify which environmental issues are relevant to this CFMP. Our Scoping exercise identified issues that are not relevant to this type and level of plan: allowing us to exclude these issues and focus our assessment on what is most important. To help us do this we consulted widely on a Scoping Report which was published in March 2006.

The scope of this SEA was determined by: • developing an understanding of the flood risk management context for the catchment, including current flood risk to people and the environment (we also considered the economy), and the potential constraints and opportunities to the management of flood risk; • undertaking a review of the environmental context of the catchment, including identifying relevant trends; • a review of relevant plans and policies, including an assessment of their relationship with catchment flood management planning; • identifying relevant environmental protection objectives from these plans and policies and consideration of how the CFMP might conflict with these, or influence their achievement; and • consultation with key stakeholders (see previous Section B2), including the SEA statutory consultation bodies Natural England and English Heritage.

The environmental and social issues scoped into the SEA were then used alongside economic issues to develop a suite of policy appraisal objectives, indicators and, where possible, targets (see Section 5.3 CFMP Objectives. Throughout this process we drew on the knowledge and vision of our CFMP Steering Group (see Section 1.5 Involving others) to help understand what matters in the catchment and shape what this plan was trying to achieve. Following our formal Scoping exercise, we considered what the future might look like, including what the effects of climate change could be, and the impact of future development pressures and changes in land management. While we can not predict the future with complete certainty, we used this perspective on the future to help us understand the scale of changes we could face in the future and so consider them explicitly within the development of the plan.

Table B3 summarises the issues we scoped into the development of the plan, and the resulting broad objectives we developed against which to test our alternative options. Not all of these issues are equally relevant everywhere in our plan area, and we also drew on other relevant policies, plans and programmes to identify opportunities and constraints for individual areas (policy units) within the plan area.

Environment Agency River Adur CFMP – Appendix B (September 2008) 24 Table B3 Scope of the SEA in relation to the CFMP Environmental Scope and Justification Relevant environmental Relevance to the CFMP Topic objective Scoped in Scoped out Population and People and properties Disease as a result of flooding. A Ensure the impact of flooding There are people at risk from flooding Human Health exposed to flooding and the robust assessment of the risk on people and properties across the CFMP area, a total of risk of being drowned due to associated with these impacts is does not significantly increase approximately 400 (1% annual flooding. not established for this level of in the future (for example due probability), the majority of which are plan. to climate change). located in the densely populated Risk flooding to people has Lower Adur and Ferring Rife. There been considered for all The CFMP will not have a Ensure the disruption caused may be additional people at risk from populations in the catchment significant effect on employment by flooding to transport and the Teville Stream. We do not with specific quantitative at a catchment level; this will be critical infrastructure does not currently have sufficient information analysis of those in assessed at project EIA stage. significantly increase in the to assess the number of people at floodplains. future (for example due to risk in the Teville Stream catchment. The CFMP will not have a climate change). Nationally and regionally significant effect on noise at a There are approximately 150 important infrastructure and catchment level; this will be residential properties at risk from a transport routes which are in assessed at project EIA stage. 1% annual probability event across the 1% AEP outline or the catchment. There are also people greater. at risk from surface water, groundwater, and urban drainage flooding, particularly in Brighton and Hove, where key transport routes were disrupted in 2000.

There are also 1 sewage treatment works, approximately 2km of main road and a negligible length of railroad at risk from flooding (1% annual probability).

Material Assets Economic damage and Ensure flood damages do not Across the CFMP area, AAD due to Annual Average Damages significantly increase in the flooding of property are (AAD) to properties and future (for example due to approximately £0.22 million (1% agricultural land. climate change). annual probability), the majority of which occur in the densely populated Recreation and amenity value Ensure that river channel and Lower Adur and Ferring Rife of waterways and flood defence maintenance catchments.

Environment Agency River Adur CFMP – Appendix B (September 2008) 25 Environmental Scope and Justification Relevant environmental Relevance to the CFMP Topic objective Scoped in Scoped out countryside. expenditure is appropriate to the economic damage of AAD to agricultural land are flooding. approximately £0.2 million and the area of agricultural land at risk totals approximately 15km2 (1% annual probability).

Tourism is of significant economic importance to the catchment especially in the coastal areas. There is one caravan park located in Ferring and one in Sompting which are both at risk from fluvial flooding. Not only should the amenity value of the area be protected from flood damage or intrusive flood management, there is also potential to increase it through wetland creation, river restoration and other flood alleviation measures.

Landscape Landscape designations Landscape character areas Restore rivers and floodplains Areas of the High Weald and Sussex including proposed National to a naturally functioning state Downs AONBs and South Downs Park, Areas of Outstanding where feasible. proposed National Park and ESA are Natural Beauty (AONBs), at risk from flooding. Approximately proposed National Parks and 4.2km2 of these sites are at risk from Environmentally Sensitive a 1% annual probability flood event. Areas (ESAs). This area increases only slightly in the future.

Historic This CFMP does not have For the purposes of the CFMP Not applicable There are nearly 3,000 listed Environment, potential to significantly process it can be assumed that buildings within this catchment of including cultural, impact on flood risk to listed buildings located within the which only 6 are currently at risk from architectural and buildings. floodplain have potential to suffer a 1% annual probability flood event. archaeological damage during flooding. Listed This number increases by only 2 in heritage Buildings are the only historic the next 50-100 years. This CFMP assets which we can be certain therefore does not have the potential

Environment Agency River Adur CFMP – Appendix B (September 2008) 26 Environmental Scope and Justification Relevant environmental Relevance to the CFMP Topic objective Scoped in Scoped out are buildings and can therefore to significantly impact flood risk to be assumed to have potential to listed buildings so no specific be damaged by flooding. Other objective has been included. These historic assets have therefore not identified sites have therefore been been considered in this CFMP. considered as constraints to FRM activities, along with other historic The CFMP could have a environment assets. significant effect on Conservation Areas. However, due to the large number of these sites within the CFMP area these effects will be assessed at project stage.

The risk of impacting upon other known and unknown undesignated heritage sites and/or features of archaeological interest is considered to be outside the scope of this plan and any potential impacts will be considered where necessary at project stage. Air quality No air quality issues are There is no potential for CFMP Not applicable Not applicable relevant to this level of plan policies to influence issues that effect air quality, e.g. emissions or generation of particulate matter at a strategic level. Air quality issues are therefore not considered to be significant and have been scoped out of the assessment.

Climatic factors The plan explicitly considers There is no potential for CFMP Not applicable Not applicable the implications of climate Policies to influence issues that change on flood risk. Our affect the local climate. policies are therefore aiming

Environment Agency River Adur CFMP – Appendix B (September 2008) 27 Environmental Scope and Justification Relevant environmental Relevance to the CFMP Topic objective Scoped in Scoped out to help society to adapt to climate change Biodiversity, fauna Sites of Special Scientific There are no sites designated as Protect and enhance Although there are no SPAs, SACs or and fauna Interest (SSSIs) and Sites of Special Protection Areas (SPAs), nationally and internationally Ramsar sites in the CFMP area, Nature Conservation Special Areas of Conservation important species and there are numerous Sites of Nature Importance (SNCIs) and (SACs), Ramsar within the habitats. Conservation Importance (SNCIs), of Biodiversity Action Plan CFMP area. which approximately 3.3km2 are at (BAP) Habitats and Species Restore rivers and floodplains risk from flooding (1% annual where these have some Sites of local conservation to a naturally functioning state probability), including the River Adur dependence on the water importance have not been where feasible. Water Meadows, Wyckham Woods environment and flooding. included. The CFMP will not and the Ferring Rife and Meadows have a significant effect on sites SNCIs. There are also SSSIs Restoration of floodplain of local conservation importance designated for their ecological or function and naturalisation of at a catchment level; this will be geological importance at risk from river channels. assessed at project EIA stage. flooding. None of these SSSIs require Water Level Management Plans (WLMP) and only an area of approximately 0.06km2 at risk from flooding (1% annual probability). Of these, only the Adur Estuary SSSI is at significant risk of flooding.

The Local BAP for Sussex includes action plans for coastal and floodplain grazing marsh, saltmarsh, chalk grassland and heath and several other habitats that are all found in the CFMP area. BAP priority species in the catchment include the otter, great crested newt, pipistrelle bat and brown/sea trout. Soils FRM policy could have a The CFMP will not have a Reduce the impact of muddy The South Downs have steep slopes significant effect of surface significant effect on coastal flooding. with poorly draining silty soils which water run-off on erosion of geomorphology. contribute to surface water flooding in soils from the land and on Restore rivers and floodplains parts of the catchment which in turn transport of sediment. The CFMP will not have a to a naturally functioning state leads to problem muddy flooding in

Environment Agency River Adur CFMP – Appendix B (September 2008) 28 Environmental Scope and Justification Relevant environmental Relevance to the CFMP Topic objective Scoped in Scoped out significant effect on where feasible. the urban areas downstream of the FRM policy could have direct contaminated land at a South Downs, namely Worthing and or indirect effects on fluvial catchment level; this will be Brighton and Hove. geomorphology and could assessed at project stage. offer opportunities to restore Poor agricultural practice can natural systems. FRM policy will not have a significantly increase surface water significant effect on geology at a run-off rates and therefore increase catchment level; this will be flood risk downstream. Flooding has assessed at project stage. been caused as a result of poor land management practices in the past at FRM policy will not have a direct Sompting, Patcham, Bevendean, or indirect significant effect on Woodingdean, Ovingdean, Westdene land use and land management. and Mile Oak. Water The potential for flooding and FRM effects on water resources Protect and enhance There are several water quality FRM to affect the (surface and groundwater) are nationally and internationally issues in the catchment including achievement of good not of strategic importance in the important species and diffuse pollution from urban areas ecological potential of water catchment. habitats. and roads entering watercourses, bodies. run-off from agricultural land and There is no significant potential increased sediment from soil erosion for an increase in poor quality caused by surface water run-off and water (and secondary impact on also from scour within the river designated sites). channels, which can damage fish spawning habitats. There is an There is limited potential for opportunity for flood risk flooding to affect the quality of management to include features water through foul water flooding, which both improve water quality and surface water flooding and/or the alleviate the risk of flooding e.g. flooding of water treatment creation of wetlands. works.

Environment Agency River Adur CFMP – Appendix B (September 2008) 29 B4 Assessment and Evaluation of Environmental Effects

B4.1 Strategic options and appraisal process

We have considered six generic options in our policy plan, which are listed in Table B4.

Table B4 Definition of policy options Policy option Risk management strategic approach 1. No active intervention (including flood warning and Accept the risk – both current and future maintenance). Continue to monitor and advise increases in risk 2. Reduce existing flood risk management actions Accept the risk – both current and future (accepting that flood risk will increase over time) increases in risk 3. Continue with existing or alternative actions to Accept the risk – our current scale of manage flood risk at the current level (accepting actions is sufficient to manage the current that flood risk will increase over time from this risk, and future increases will be acceptable baseline) 4. Take further action to sustain current scale of flood Accept the risk – but in the longer term risk into the future (responding to the potential take action to ensure the risk does not increases in flood risk from urban development, increase from current level land use change, and Climate Change). 5. Take further action to reduce flood risk (now and/or Reduce the risk – lower the probability of in the future) exposure to flooding and/or the magnitude of the consequences of a flood, and hence the risk 6. Take action to increase the frequency of flooding to Reduce the risk by transferring the risk to deliver benefits locally or elsewhere, (which may other locations where the risks (typically the constitute an overall flood risk reduction, for consequences) are positive example for habitat inundation).

These options relate to the outcome of flood risk management in terms of the scale of risk and management activity compared to today. Deciding on the specific measures needed to achieve these outcomes is not the purpose of the CFMP. However, we do need to appreciate whether or not the change in risk under a particular policy is generally feasible and desirable in terms of where the water goes in the catchment. To appreciate this we need to understand how the catchment works in times of flood so that our policies make sense. The water needs to go somewhere when it floods and we need to understand that if we prevent water from flooding homes in one location what the knock-on effects would be in another location.

In order to understand how the catchment works we develop models that can draw on information about the amount of rainfall and show to some extent how this drains off the land and into the river systems. We can then consider at a broad scale how the flow of water within the catchment could change over time with or without management intervention. Of particular importance in driving future changes in flood risk are: • the potential impact of climate change on flooding due to increased rainfall and sea level rise; • the potential impact of new development due to extra run-off from impermeable surfaces as well as new properties being developed in areas exposed to flooding; and

Environment Agency River Adur CFMP - Appendix B (September 2008) 30 • the potential impact of changes in land management because this can change the permeability of the catchment and how the rate at which water drains into the river system.

To consider what future flood risk might be like, including the effect of having no management intervention, we have considered a number of future scenarios. These scenarios aim to establish what changes there could be in the three important drivers of change listed above (climate change, development and land management). To develop reasonable predictions of change we have looked at past changes and had discussions with our Steering Group to arrive at reasonable projections of what the future could be like. To consider the impact of climate change on flooding we have used the government guidance issued by Defra (2006). A more detailed explanation of the scenarios used is given in Section 4.2 Scenarios.

Our appraisal of the alternative policies is undertaken by considering how the flow within the catchment could change in the future. This understanding is done at a high level using our models, complemented with expert judgement on how water flows through the catchment during times of flood. For example, we might say that if land management practices changed in the headlands of a catchment, the land would be more permeable and this would reduce the rate at which rainfall enters the river system downstream. Such a change in how water flows through the catchment could then reduce the volume of floodwater downstream (and reduce the frequency of flooding to homes in this downstream location).

Our consideration of how the catchment works, and what the current and future risks are has allowed us to divide the catchment up into smaller geographical areas that we have called policy units. In each policy unit we have considered how the risks arise (using a source- pathway-receptor model) and what our specific objectives are. We have considered other policies, plans and programmes to see where there may be objectives and constraints that our plan could contribute to or that we need to take account of. For example, a BAP may identify habitat improvement such as creation of wet woodland. Our investigations could start to show that if the area adjacent to the river corridor was to flood more frequently, then this could potentially help contribute to achieving the BAP improvements. The process of SEA encourages us to make these links with other plans so that we can help deliver broader benefits and reduce conflict between our flood risk management policies and other aspirations. We have done this during the review of other plans and considered others’ objectives as opportunities or constraints to our policy development, as an integral part of our appraisal.

Environment Agency River Adur CFMP - Appendix B (September 2008) 31 Policy Appraisal Tables CFMP title: River Adur CFMP

Policy author: Capita Symonds Date on which policy appraisal was December 2006 started: Iteration number: Draft 3 The following forms are based on our integrated policy appraisal process, modified for use on CFMPs. The forms pull together all the key data and information gathered throughout the CFMP development process.

The first four and last forms are generic to the CFMP area and these are listed below. A further seven forms are specific to each policy unit and are presented in order of policy unit. Index of Policy Appraisal forms

Generic forms: Form B1 – Purpose of the CFMP. Form B2 – Meeting legal requirements. Form B3a – Summary of flood risk – including an explanation of model results from ‘drivers’. Form B3b - Source-pathway-receptor table with objectives and suggested flood risk management responses. Form B4 – CFMP policy options. Form B11 – Signature of CFMP project manager.

For each policy unit: Form B5 – Summary of current and future levels of and responses to flood risk. Form B6 – Appraisal of policy options against policy unit objectives. Form B7 – Summary of losses and gains. Form B8 – Summary of preferred policy. Form B9 – Requirements for further policy development and appraisal. Form B10 – Indicators for monitoring, review and evaluation.

Environment Agency River Adur CFMP - Appendix B (September 2008) 32

Form B1 Purpose of the CFMP This form contains the key catchment specific objectives, opportunities and constraints that need to be taken into account when developing the CFMP, including Biodiversity Action Plan targets, environmental targets and housing targets. These factors have been reviewed and amended through consultation undertaken in the scoping stage and during the draft CFMP stage. Catchment objectives Economic - Ensure flood damages do not significantly increase in the future (for example due to climate change). - Ensure that river channel and flood defence maintenance expenditure is appropriate to the economic damage of flooding.

Social - Ensure the impact of flooding on people and property does not significantly increase in the future (for example due to climate change). - Ensure the disruption caused by flooding to transport and critical infrastructure does not significantly increase in the future (for example due to climate change). - Reduce the impact of muddy flooding.

Environmental - Restore rivers and floodplains to a naturally functioning state where feasible. - Protect and enhance nationally and internationally important species and habitats. Catchment opportunities and constraints Opportunities: • Enhance the character of the landscape and increase amenity opportunities for recreation, tourism and leisure activities. • Help meet national biodiversity action plan (BAP) targets. • Work with the High Weald AONB Joint Advisory Committee to achieve the targets set in the High Weald AONB Management Plan to maximise the opportunities for natural processes to reduce flooding through the adoption of river restoration policies, whilst enhancing landscape character. • Move toward more natural rivers and drainage networks, as outlined within PPS25, will mean we can achieve more efficient and sustainable water management, whilst enhancing landscape character. • Investigate removal of Environment Agency owned and maintained existing raised defences to reinstate the floodplain between Partridge Green and Steyning and between Steyning and Shoreham to a naturally functioning state, to provide flood storage and enhance conservation value and biodiversity. • Influence the coastal defence strategy, along the Lower Adur, Teville Stream and Ferring Rife, to improve the sustainability of flood risk management in the this area. • Provide development control advice to ensure no increase in run-off from the new development proposed in the South East Plan (e.g. Brighton and Hove, Worthing, Shoreham and Burgess Hill). • Reduce flood risk and improve water quality by promoting and encouraging the use of SuDS in the proposed urban developments in Brighton and Hove, Worthing, Shoreham and Burgess Hill. • Investigate the feasibility of incorporating the Teville Stream into the Floodline Warnings Direct service by installing new level gauges on the Teville stream. • Continue local authority and Environment Agency support of the Flood 1 project in relation to groundwater flooding. • Develop a flood warning system for groundwater flooding. • Continued practice and development of the Emergency Response Plan in Brighton and Hove, Worthing, Shoreham, and Burgess Hill. • Reduce surface water run-off and soil erosion by supporting the existing and future management policies regarding environmentally sensitive farming practices (e.g. those set out by Brighton and Hove City Council). • Support the existing flood defence measures in relation to surface water flooding, such as Environment Agency River Adur CFMP - Appendix B (September 2008) 33 bunds provided by Brighton and Hove City Council. • Potential for improving the current defences, for example possible installation of demountable or temporary defences in Shoreham and Burgess Hill. • Improvements in the efficiency of channel and flood defence maintenance processes. • Effective and efficient use of developer contributions for flood risk management. • To work with Defra and farmers to produce soil management plans which have a benefit to flood risk through reducing the run-off rate. Constraints: • Government and international legislation, environmental management policies, plans and strategies for the catchment must be complied with, such as accommodating new housing within the catchment as detailed by the South East Plan and compliance with the Habitats Directive. • Existing urban development may prevent reinstatement of natural river processes. • Individual homes and properties are currently at risk of flooding. • Transport links in the catchment are a vital part of the communication network regionally, nationally and internationally, in particular the railways connecting London to the south coast and connecting the coastal towns and cities, the A23, A24, A27, A259, A283 and A2032. • Some environmentally designated habitats are susceptible to changes in flood frequency, floodwater chemistry, groundwater levels and drainage system maintenance. • Historic development and some heritage designations in Steyning, Bramber and Upper Beeding present permanent physical obstructions. • Presence of protected species with specific water level, water quality and habitat requirements, for example in the Adur Estuary SSSI. • Location of electricity pylons adjacent to the Lower River Adur (currently protected by existing defences). • No degradation of existing fish passage and habitat. • Visual impact of flood risk management activities within the proposed National Park or Areas of outstanding Natural Beauty. • Steep catchments of the South Downs result in rapid run-off and quick responses to rainfall events. • A suitable level of productivity from agricultural land needs to be retained. • Changes to flood risk management can affect the landscape, its character and value as an amenity. • CFMP objectives and policies must complement those of the Shoreline Management Plan (SMP) that affects the CFMP area. • Available funding for the initial implementing new flood risk management schemes. • Older flood defence structures are likely to be costly to maintain. • Limited available information on surface and groundwater flood damages. Local Biodiversity Action Plan (from Rio to Sussex): BAP targets consisting of specific species action plans (SAPs) and habitat action plans (HAPs) Species Action Plans (SAPs) for Sussex: Barn Owl (Tyto alba) The Rother, Arun, Adur and Ouse river valleys of Sussex were considered to be nationally important in the Hawk and Owl Trust’s (HOT) National Conservation Plan for the Barn Owl, 1988-2008. Barn Owls are birds of low-lying open farmland and woodland edge. They feed on small mammals, predominantly the short-tailed vole, but also mice, shrews and small rats. They require extensive areas of prey-rich habitat, usually rough, ungrazed or lightly grazed tussocky grassland in the form of whole fields, field margins, parkland, orchard and newly planted plantations. There is considerable potential to increase the Barn Owl population in Sussex. Black Poplar (Populus nigra) The black poplar is considered to be native to Britain and is a tree of wet woodland and forested floodplain. Historically it is a significant tree in Britain and once played a substantial role in local economies and culture. In Sussex, thirty three individual trees have so far been identified. Although the number of black poplars in the country is low, it is likely that the Sussex population is significant on a national scale. Brown Hare (Lepus europaeus) The brown hare is a common and conspicuous farmland species in Britain, probably introduced by the Romans in ancient times. Formerly considered abundant, the brown hare appears to have undergone a substantial decline in numbers since the early 1960s. Carder Bumblebee (Bombus humilis) The carder bumblebee makes its nest on the surface of the ground at the base of long vegetation, often under accumulated plant litter. It has most often been Environment Agency River Adur CFMP - Appendix B (September 2008) 34 recorded as associated with areas of grassland supporting a large number of plant species with long corolla flower types, notably those belonging to the plant families Lamiaceae and Fabaceae. It is one of a number of bumblebee species to have undergone a drastic reduction in range and abundance, as a result of the loss of this habitat in the modern agricultural landscape, although it appears to be able to survive in less extensive areas of flower-rich habitat compared with some bumblebee species. Duke of Burgundy (Hamearis lucina) The Duke of Burgundy butterfly has a primarily central southern distribution in England, with isolated populations on the limestone of south Cumbria/north Lancashire and the north Yorkshire moors. The Duke of Burgundy was once widespread throughout much of lowland England and there are a few historical (pre 1940) records from Wales. The butterfly is found on most areas of the chalk grassland of lowland England, with centers of distribution in Wiltshire, Hampshire and West Sussex. European Otter (Lutra lutra) The Eurasian or European otter is a semi-aquatic mammal that inhabits a variety of wetland environments; ranging from rivers, lakes and streams to marshes and coastal areas. Hunting in the 1960s, the introduction of organochlorine pesticides and habitat loss from land drainage activities significantly affected populations in the UK. By the late 1970s only 6% of sites inspected in the UK showed signs of otters. Now legally protected otter populations have started to slowly rise. Recent evidence of otter activity in a number of catchments in both East and West Sussex has been found, although there is some speculation as to whether the sightings are due to natural recolonisation or reintroductions that have taken place. Fen Raft Spider (Dolomedes plantarius) The fen raft spider is a wetland spider dependent on permanent, standing or slow moving water. It is associated with nutrient-poor water of near neutral or alkaline pH. It lives on the surface of pools and ditches, and amongst emergent vegetation; typically it hunts from ‘perches’ on stems emerging from the water, taking a wide range of invertebrate prey on or below the surface. Emergent, stiff-leaved vegetation in open, sunny conditions is also required for the construction of nursery webs in which the young are reared. Areas of suitable habitat have been identified in West Sussex for the location of a population of this species. Glow worm (Lampyris noctiluca) Actually a beetle, with preferred habitats defined as “downland, pastures, meadows, roadside verges, hedgerows, railway embankments, churchyards, golf courses, gardens, moorland, heathland, quarries, canal towpaths, and waste ground”. The structure of vegetation, in other words its height, density, shade and shelter, may be more important than its composition. Also, a mixture of open grass and some form of cover such as scrub, brambles or woodland edge is preferred to pure woodland or pure grassland. Good populations present in the catchment in the South Downs and to a lesser frequency in the Low Weald. The habitat requirements for the insect are maintained at the Lewes Railway Land Local Nature Reserve. Great Crested Newt (Triturus cristatus) Sussex appears to have an internationally significant resource of this species, even though the majority of sites have yet to be identified. The distribution is by no means uniform across East and West Sussex. The greatest concentration of breeding ponds appears to be in the middle of Sussex, with Lewes and Wealden Districts having the largest number, followed by Mid-Sussex and Horsham Districts. Populations have also been identified within the conurbations along the south coast. Areas of the Downs around Brighton are known to support viable populations. Pipistrelle Bat (Pipistrellus) The pipistrelles are Britain’s smallest bats and are the most comment species in towns. Although it remains the most abundant and widespread bat species in the UK, the pipistrelle is thought to have undergone a significant decline in numbers this century. Estimates from the National Bat Colony Survey suggest a population decline of approximately 70% between 1978 and 1993. The pipistrelle can be found throughout Sussex, in varying population densities. The highest populations are found in the Wealden areas and the lowest on the Downs. Skylark (Alauda arvensis) One of the most widespread birds of the UK, with over 1 million breeding pairs, the resident population is joined in winter by a significant proportion of the northern European population - possibly up to 25 million individuals. Nonetheless, the UK breeding population of skylark on lowland farmland declined by 54% between 1969 and 1991. The skylark is still commonplace in Sussex, particularly on the Downs, although its distribution is somewhat patchy. Song Thrush (Turdus philomelos) This is a common and widespread species, which is declining throughout the UK. Following the winter of 1962/63, the population declined but recovered to a stable level within three to four years. The numbers subsequently remained stable until the mid 1970s after which they declined steadily, with an estimated reduction of 73% in farmland and 49% in woodland habitats. These birds are generally more abundant in the east than the west of the country. Song thrush densities are highest in the Weald. Stag Beetle (Lucanus cervus) This large and conspicuous beetle is rare and protected in some European countries, but is still widespread in southern England, especially the Thames valley, north Essex, south Hampshire and West Sussex. It also occurs fairly frequently in the Severn valley and

Environment Agency River Adur CFMP - Appendix B (September 2008) 35 coastal areas of the southwest. Outside these areas the records are sparse and often old, indicating some contraction of the beetle’s range. This species is well distributed within West Sussex, with areas around Shoreham being traditional geographical hot spots. Habitat Action Plans (HAPs) for Sussex: Arable Land (including Field Margins) Arable land under this definition covers all cultivated land, including arable crops, grass leys, vegetables and non-food crops as well as the field margin. There is a range of different geology, soil types and landscape across Sussex which favour differing farming practices and support widely differing plant and animal communities. Chalk Grassland (Lowland calcareous grasslands) In the UK chalk grasslands are developed on shallow lime-rich soils most often derived from chalk and limestone rocks. Orchid-rich chalk grassland is identified as a priority in the European Habitats Directive. About a fifth of the country’s chalk grassland was lost between 1966 and 1980. It now covers only 3% of the area on the South Downs; the remaining resource is largely confined to slopes too steep to plough, such as the north-facing escarpment. Coastal Vegetated Shingle Shingle is defined as sediment with particle sizes in the range 2-200mm. It is a globally restricted coastal sediment type with few occurrences outside northwest Europe, Japan and New Zealand. The vegetation communities of shingle features depend on the amount of finer materials mixed in with the shingle and on the hydrological regime. Small areas of vegetated shingle occur at a number of sites within the CFMP area, including Shoreham, Littlehampton, Kingston, Worthing and Lancing. Estuaries (including mudflats) A natural dynamic estuary comprises extensive areas of both aquatic and terrestrial habitats, the composition and location of which will change over time as a result of geomorphological processes. In addition to dynamic processes, the aquatic elements of estuarine systems are dependent on two main factors, the land levels and the degree of salinity. Mudflats are sedimentary intertidal habitats created by deposition in low energy coastal environments. In the CFMP an area of 37 hectares has been classified as an estuary with mudflats and sandflats and the component habitats. Floodplain Grassland The habitat types covered by this plan are periodically inundated pastures or meadows with ditches, which maintain water levels, containing standing brackish or fresh water. Wet grassland have a high nature conservation value and support a wide range of plant, bird and invertebrate species, many of which are rare and/or declining. The rivers Adur, Arun, Ouse and Cuckmere all have important areas of floodplain grassland. Hedgerows (species-rich and/or ancient hedgerows) A hedgerow is defined as a boundary feature, which are less than five metres wide and comprised of predominantly shrub and/or tree species. A species-rich hedgerow is one that has, on average, five or more native, woody, shrub or tree species per 30m length. An ancient hedgerow is one that was in existence before 1850, predating the establishment if current civil parishes. In Sussex the Weald appears rich in ancient and species-rich hedgerows. Lowland Heathland Lowland heathland forms an open landscape, generally occurring on poor, acidic, sandy soils and is characterised by the presence of plants such as heather, dwarf gorses, and cross- leaved heath. Heathland is a priority for nature conservation because it is an internationally rare and threatened habitat. In Sussex, heathland occurs principally in two Natural Areas; the Wealden Greensand and the High Weald, but in former times it may have occurred more extensively in the Low Weald and elsewhere. Marine HAP for Sussex is currently under production (January 2007). Maritime Cliff and Slope HAP for Sussex is currently under production (January 2007). Minerals Mineral sites in West Sussex include quarries and pits from which gravel, sand, clay, chalk and sandstone are being, or have been, extracted. Although mineral extraction is a commercial operation, mineral sites encompass a high range of different habitats, features and conditions and are potentially very important for biodiversity conservation. There are in the region of 50 mineral sites in Sussex (including both active and restored sites) that are likely to have at least some interest for biodiversity or geodiversity. Road Verges The road verge can be regarded as being made up of a wide range of habitats and their associated species. The habitat is determined by a range of factors including the underlying geology, the naturally derived soils or soils which have been important onto the verge and the management of the verge. The habitats found on the roadside verges in West Sussex are extremely varied, currently there is little recorded detailed knowledge of the physical and biological characteristics of the whole resource. Saline Lagoons Bodies of saline water, either natural or artificial, that are partially (but not completely)

Environment Agency River Adur CFMP - Appendix B (September 2008) 36 separated from the adjacent sea. Saline lagoons are important for both the plant and invertebrate communities they contain, some of which are reliant on this habitat. Saline lagoons are a nationally rare habitat type; in Sussex they cover a total of 69 hectares (only 5% of the total English coverage). Standing Fresh Water This plan covers all standing fresh waters from ponds of one square metre up to large lakes. Small ponds are very important features of the Sussex landscape. In the past these would have been created through seasonal flooding and meandering of natural river systems. Sussex Woodlands Includes a great range of types and those present within the CFMP area are; Lowland Beech and Yew Woods, Wet Woodlands Lowland Mixed Deciduous Wood and Undetermined woodlands. Sussex is one of the most wooded parts of lowland Britain, with the Weald having the greatest cover of woodland in Britain. Unimproved neutral grassland and acid grassland Unimproved neutral grassland is a feature of lowland mineral soils with a pH between 5 and 6.5 and which are neither very wet nor very dry. Neutral grasslands are found throughout Britain where suitable soils and soil moisture are present. In Sussex unimproved neutral grasslands are relatively evenly distributed through the Sussex Weald. Dry acid grasslands are fairly widespread in Britain where sols are base poor. Recorded dry acid grasslands in Sussex are few in number and randomly scattered where suitable soils are present, but may be more widely associated with heathland. Urban the definition of urban areas is broad to cover all areas of human settlement. The biodiversity in urban areas include a complex mosaic of semi-natural and artificial habitat types, many of which are covered in other individual Habitat Action Plans (HAPs). This includes urban woodland included in the Woodland HAP and urban green spaces that are not covered in other plans. There are a large number of additional environmental initiatives and objectives that relate to the CFMP area. The main ones are as follows: • The Environmentally Sensitive Areas Scheme was introduced nationally in 1987 to offer incentives to encourage farmers to adopt agricultural practices which would safeguard and enhance parts of the country of particularly high landscape, wildlife or historic value.

• The South Downs is classified as an Environmentally Sensitive Area (ESA) and 250 voluntary agreements under the ESA scheme across the South Downs were made.

• Defra introduced a new Environmental Stewardship Scheme in March 2005 which supersedes (with enhancements) the Environmentally Sensitive Areas and Countryside Stewardship Schemes. These schemes help to achieve targets within the BAPs, for example the schemes include payments for reinstating hedgerows hence supporting the Sussex Hedgerow Habitat Action Plan. Additionally reducing flood risk is stated as a secondary goal to the schemes.

• Others Rural Development Programme schemes include Woodland Grants Scheme, Farm Woodland Premium Scheme, Hill Farm Allowance, and the Organic Farming Scheme.

• West Sussex County Councils area-based Countryside Management Unit implements heathland restoration/recreation schemes in liaison with private landowners in both the High and Low Weald. By 1998, 1,109 hectares of heathland were managed under Defra's Countryside Stewardship Scheme and 128 hectares under English Nature's Wildlife Enhancement Scheme (WES).

• Adur District Council produced a wetland feasibility study on the lower Adur in March 1997 entitled ‘The potential of restoration of wetland biodiversity’.

• A River Adur restoration project at Knepp Castle Estate is proposed to commence in 2007. The aim is to re-naturalise the river, restoring its natural meaders and thereby reintegrating the surrounding floodplains. In doing this it is hoped the process will encourage the return of insects and amphibians, important marsh plants and riverine trees like black poplar. Future housing targets for the CFMP are as follows: • The South East Plan – Proposed Sub-Regional Strategy for the Sussex Coast recommends developing up to 17,000 homes between Worthing and Brighton and Hove between 2001 and 2026, with accompanying infrastructure improvements linked to an emphasis on economic and business growth.

• Annual average housing targets in South East Plan Policy HC1 shown in brackets; Adur (130), Worthing (330), Horsham (620), Mid Sussex (705) and Brighton and Hove (550).

Environment Agency River Adur CFMP - Appendix B (September 2008) 37

• The West Sussex Structure Plan 2001 – 2016 sets a target to ensure the provision of an annual average rate of 3,100 dwellings within Adur, Mid Sussex, Horsham Districts and Worthing Borough.

• The East Sussex and Brighton and Hove Structure Plan 1991 – 2011 sets a total housing provision of 9,400 dwellings in Brighton and Hove by 2011.

Environment Agency River Adur CFMP - Appendix B (September 2008) 38

Form B2 Legal requirements This form lists the legal requirements and Government and Environment Agency targets that CFMP policy needs to comply with or support. Environment Agency corporate measures for flood risk management: • Sustained objections to development in Flood Zones.

• People taking appropriate action in response to flooding based on our advice.

• Increase the proportion or properties (homes and businesses) within the indicative floodplain that have been offered an appropriate flood warning service.

• Increase the number of houses which benefit from reduced flood risk.

• All flood systems to be in the condition required by the performance specifications.

• Delivery of Operation Public Safety (OPUS).

• Produce Catchment Flood Management Plans (CFMPs) for all principal catchments.

• All data stored in the National Flood and Coastal Defence Database (NFCDD) will have Data Quality Indicators.

• All new data entered in NFCDD in the year will be spatially accurate and be fully attributed.

• Environment Agency Flood Maps comply with policy guidance.

• Deliver Water Level Management Plans on 72 priority SSSIs to achieve Favourable/Unfavourable Recovering condition by 2010.

• Create at least 200 hectares of new Biodiversity Action Plan (BAP) habitats as a result of flood management activities, of which at least 100 hectares should be salt marsh and mudflat.

• Decrease the proportion of major infrastructure within the floodplain that is at risk of not being available for its intended use at times of flood.

• Optimise economic return from relevant Flood Risk Management activities.

• Improve the effectiveness and efficiency of investment in asset management.

• Improve efficiency by reducing the cost of decision making and overheads and savings from procurement best practice.

• As part of the above target, reduce the cost of developing and implementing capital flood defence schemes, as a percentage of total relevant costs (taken year on year). Government targets: • High Level Target 4 – Biodiversity. • High Level Target 5 – Flood defence inspections and assessment of flood risk. • High Level Target 12 – Development and Flood Risk. Legal requirements: • Conservation (Natural Habitats, &c.) Regulations 1994. • The Water Environment (Water Framework Directive) (England and Wales) Regulations 2003. Will the appraisal include/meet other specialist appraisal needs? Yes The appraisal process has been prepared within the spirit of the SEA Directive. Thus, in addition to appraising policies against catchment objectives and legal Is so, state which: requirements, policies will also be appraised against catchment opportunities and constraints.

Environment Agency River Adur CFMP - Appendix B (September 2008) 39

Summary of flood risk – including explanation of model results from Form B3a ‘drivers’ This form provides an overview of flood risk within the catchment. It contains maps showing the extent of flooding during the 1% annual probability flood event, a summary table of current flood risk and a summary table of environmental issues related to flooding.

This form also contains a table summarising the likely future changes in the catchment for a range of future scenarios and the flooding consequences of these changes. Estimates of the 1% annual probability flood damages for the current basecase and the future scenario for each catchment are also included.

Adur East Branch

Figure B3.1 - Adur East Branch: Broadscale model flood outline – 1% annual probability fluvial flood event (at 2006 baseline conditions) Environment Agency River Adur CFMP - Appendix B (September 2008) 40

Current flood risk – Adur East Branch Flooding source and places at Pathway and people/ property Current flood risk and scale of risk affected disruption Burgess Hill River channel under capacity Less than ten properties are can cause localised flooding. thought to be at risk from flooding Fluvial flooding from River in Burgess Hill. Adur and tributaries running Under capacity and blocked through Burgess Hill. urban drainage systems. Flooding is generally short lived, and relatively shallow. Surface water flooding from Localised flooding to properties urban and road drainage and roads in Burgess Hill. Both disruption and hazard are systems. assessed as low.

Flood damages only occur under extreme and unlikely flood events and rely on blockage of infrastructure; flood risk is assessed as low. Hassocks Under capacity and blocked A small flood alleviation pond urban drainage systems. (Keymer Pond) is located to the Surface water flooding from West of Hassocks and attenuates urban road drainage systems Surface water and overland flow. the peak flows of one of the in Hassocks. tributaries running through Localised flooding to properties Hassocks. and roads in Hassocks. Flooding is generally short lived and relatively shallow, however because of the steep surrounding hills, inundation may be relatively fast, although the ground is not considered steep enough to result in dangerously high water velocities.

Less than ten properties are thought to be at risk of this type flooding in Hassocks.

Both disruption and hazard are assessed as low and therefore flood risk is assessed as low. Wivlesfield Surface water and overland flow Small localised disruption to roads in and around Wivlesfield. and properties. Surface water flooding from urban and road drainage Properties, roads and land Duration of the flooding is short systems in Wivlesfield. affected in Wivlesfield. (less than five hours) with low velocities.

Because of the low disruption and hazard the flood risk is assessed as low.

Current flood risk to the environment – Adur East Branch Current flood risk and scale of Flooding source Pathway and habitat affected impact None identified

Environment Agency River Adur CFMP - Appendix B (September 2008) 41

Figure B3.2 - Adur East Branch: Broadscale model flood outline – 1% annual probability fluvial flood event (at 2106 baseline conditions)

The following tables provide a summary of how flooding may change in response to future changes within the catchments, and what the implications of these changes might be. A broadscale model has been used to investigate the impact of these changes and has allowed us to quantify the effect on flood damages.

Environment Agency River Adur CFMP - Appendix B (September 2008) 42 Adur East Branch – Future scenario (climate change: 20% additional fluvial flow and sea level rise of 600mm) 1% annual probability fluvial Results from broadscale modelling flood damages (£million) Broadscale modelling showed that the catchment was insensitive to the small amount of urban growth that is predicted in the Adur East Branch area as a whole, in terms of flooding, and so was not included in this scenario.

Basecase = £0.31 Modelling climate change has shown a small increase in flood damages in this area, which is mainly due to increased fluvial flow. Scenario = £0.52

It is anticipated that urban growth in Burgess Hill will be large and as such the number of properties at risk will increase significantly in the future and as such the future damages may be larger in this community than predicted by the broadscale modelling assessment. Conclusions The Adur East Branch catchment appears not to be sensitive to our future change scenario. We have found very little serious flood damages as a result of fluvial flooding in this part of the CFMP catchment. However pressures for development may results in greater damages in Burgess Hill than predicted.

Future flood risk to the environment – Adur East Branch Current flood risk and scale of Flooding source Pathway and habitat affected impact None identified

Environment Agency River Adur CFMP - Appendix B (September 2008) 43 Adur West Branch

Figure B3.3 - Adur West Branch: Broadscale model flood outline – 1% annual probability fluvial flood event (at 2006 baseline conditions)

Current flood risk – Adur West Branch Flooding source and places at Pathway and people/ property Current flood risk and scale of risk affected disruption West Grinstead The risk of flooding is very small Road drainage problems in this catchment, with minimal to affecting the A272 and B2135, Surface water flooding and no disruption caused. causing minor road and land run-off from highway drainage. Flood risk is assessed as low to flooding around West Grinstead. none.

Environment Agency River Adur CFMP - Appendix B (September 2008) 44

Current flood risk to the environment – Adur West Branch Current flood risk and scale of Flooding source Pathway and habitat affected impact None identified

Figure B3.4 - Adur West Branch: Broadscale model flood outline – 1% annual probability fluvial flood event (at 2106 baseline conditions)

The following tables provide a summary of how flooding may change in response to future changes within the catchments, and what the implications of these changes might be. A broadscale model has Environment Agency River Adur CFMP - Appendix B (September 2008) 45 been used to investigate the impact of these changes and has allowed us to quantify the effect on flood damages.

Adur West Branch – Future scenario (climate change: 20% additional fluvial flow and sea level rise of 600mm) 1% annual probability fluvial Results from broadscale modelling flood damages (£m)

The broadscale modelling has shown that flooding in the Adur West Basecase = £0.02 Branch area of the CFMP will not increase as a result of climate change. Scenario = £0.02 Conclusions The low flood damages result from the catchment being sparsely populated and predominantly rural in nature, with lower flood risks of flooding to property and consequently lower flood damages. The damage values for the current basecase and future scenario are entirely from agricultural damages.

Future flood risk to the environment – Adur West Branch Current flood risk and scale of Flooding source Pathway and habitat affected impact None identified

Environment Agency River Adur CFMP - Appendix B (September 2008) 46 Lower Adur

Figure B3.5 – Lower Adur: Broadscale model flood outline – 1% annual probability fluvial flood event (at 2006 baseline conditions)

Environment Agency River Adur CFMP - Appendix B (September 2008) 47 Current flood risk – Lower Adur (including Brighton and Hove) Flooding source and places at Pathway and people/ property Current flood risk and scale of risk affected disruption Steyning, Bramber and Upper Overtopping of raised river The raised embankments provide Beeding embankments along the River Adur. some protection for the lower probability fluvial flood events, so Fluvial flooding from Adur, Black Under capacity and blocked urban damages are lower for the more Sewer and Tanyard Stream. drainage systems. frequent flood events. Embankments are likely to be overtopped by an Surface water flooding from urban Surface water and overland flow. exceptionally high tide or the and road drainage systems. combination of a high tide and very Properties, land and roads affected high river flows. in Steyning, Bramber and Upper Beeding 50-100 properties are at risk from the more extreme flood events in this area, which results in high flood damages to properties.

The high street, connecting the towns of Upper Beeding and Bramber, is at risk of flooding during the most severe flood events.

The overall hazard and disruption is assessed as low.

Because of the number of properties at risk under an extreme flood event the flood risk has been assessed as low. Shoreham and Lancing Surface water and overland flow. Surface water is pumped to the River Adur in times of flood, but water can Surface water flooding from run- Properties, land and Shoreham take weeks to subside in extreme off generated from the steep Airport affected. events. slopes of the South Downs. Agricultural land is worst affected, with some disruption to the airport and highways and gardens flooded.

There are a very small number of properties (less than ten) affected by the surface water flooding.

Surface water flooding is experienced approximately 1 in every 10 years.

The flood risk has been assessed as low. Brighton and Hove Intense rainfall combined with high No formal flood defences present in groundwater levels causes surface the area. Groundwater and surface water water and overland flows as flooding. drainage capacity is exceeded. Numerous properties are at risk from groundwater flooding. Transport People, property and infrastructure routes including the A23 and railway in affected in Brighton and Hove. lines are also at risk.

Because of the likelihood of flooding is not certain, and the mechanisms can be rapid or slow depending on whether flooding is from surface water or groundwater the flood risk has been assessed as low to medium.

Environment Agency River Adur CFMP - Appendix B (September 2008) 48 Current flood risk to the environment – Lower Adur Flooding source Pathway and habitat affected Current flood risk and scale of impact None identified

Figure B3.6 – Lower Adur: Broadscale model flood outline – 1% annual probability fluvial flood event (at 2106 baseline conditions)

Environment Agency River Adur CFMP - Appendix B (September 2008) 49 The following tables provide a summary of how flooding may change in response to future changes within the catchments, and what the implications of these changes might be. A broadscale model has been used to investigate the impact of these changes and has allowed us to quantify the effect on flood damages.

Lower Adur – Future scenario (climate change: 20% additional fluvial flow and sea level rise of 600mm) 1% annual probability fluvial Results from broadscale modelling flood damages (£m) The broadscale modelling has shown an increase in flood damages in Basecase = £3.10 this area, which is due to the combination of sea level rise and increased flows as a result of climate change. Scenario = £3.90 Conclusions Flood damages from the River Adur are expected to increase as a result of climate change. The increase of approximately 26% (from £3.1 million up to £3.9 million) is due mainly to additional volumes of floodwater resulting in greater depths of flooding throughout the area and therefore greater flood damages to properties and agriculture. If a fluvial flood event is combined with a large coastal flooding event, these figures are expected to increase significantly.

Under the future scenario, flooding of the urban areas (Steyning, Bramber and Upper Beeding) is likely to occur more frequently due to the climate change in the future.

Groundwater flooding has not been included as part of our broadscale modelling and our current ability to accurately predict the impact of climate change on groundwater flooding is limited. However, we do expect an increase in high intensity storms in the future, which will make flood risk worse in Brighton and Hove.

Future flood risk to the environment – Lower Adur Current flood risk and scale of Flooding source Pathway and habitat affected impact None identified.

Environment Agency River Adur CFMP - Appendix B (September 2008) 50 Ferring Rife

Figure B3.7 – Ferring Rife: Broadscale model flood outline – 1% annual probability fluvial flood event (at 2006 baseline conditions)

Current flood risk – Ferring Rife Flooding source and places at Pathway and people/ property Current flood risk and scale of risk affected disruption Approximately 50 properties are at risk from the more extreme flood Under capacity river channel in events in this area, which results Ferring the upper catchment. in high flood damages to

properties. Fluvial flooding from the Overland flow. Ferring Rife. The overall hazard and disruption

People and properties affected in is assessed as low. Surface water flooding. Ferring. Flood risk has been assessed as low.

Environment Agency River Adur CFMP - Appendix B (September 2008) 51

Current flood risk to the environment – Ferring Rife Current flood risk and scale of Flooding source Pathway and habitat affected impact None identified.

Figure B3.8 – Ferring Rife: Broadscale model flood outline – 1% annual probability fluvial flood event (at 2106 baseline conditions)

Environment Agency River Adur CFMP - Appendix B (September 2008) 52 Ferring Rife – Future scenario (climate change: 20% additional fluvial flow and sea level rise of 600mm) 1% annual probability fluvial Results from broadscale modelling flood damages (£m) The extents of the larger flood events will not change very much and it is only the depth of flooding that will increase.

The broadscale modelling has shown that damage levels within the catchment are relatively insensitive to any changes in flood flows that Basecase = £1.65 do occur. Scenario = £1.83

Tide locking due to sea level rise also lasts slightly longer, which, by reducing the ability to discharge to the sea, increases flooding on the lower parts of the Ferring Rife Conclusions The extent of the modelled flood risk area does not increase very much. For the 1% annual probability fluvial flood event, the flood damages increase by around 11% for the 100 year horizon.

The extent of the larger flood events will not change by very much and it is only the depth of flooding that will increase.

Future flood risk to the environment – Ferring Rife Current flood risk and scale of Flooding source Pathway and habitat affected impact None identified.

Environment Agency River Adur CFMP - Appendix B (September 2008) 53 Form B3b Source-Pathway-Receptor table with objectives and suggested flood risk management responses. Primary Secondary Catchment Drivers Source Receptor Aspect Indicator Responses Examples Policy Pathway Pathway Objectives No active intervention Climate River channel Overtopping of Number of Ensure the Planning policy (including flood change River and drainage river Population people impact of (future warning and (increased network embankments affected flooding on development) maintenance). inflows) people, Continue to monitor property and and advise. Number of the built Reduce existing Climate people environment flood risk Surface Sub-surface change Overtopping of Population – affected does not Flood warning management water run- flow i.e. (sea level watercourses vulnerability (according to increase due and evacuation actions (accepting off groundwater People rise) Social to future that flood risk will Vulnerability) changes. increase over time). Continue with existing or High tide Storage for Reduce flood alternative actions levels in Overtopping of Length of Influencing and tide locking risk to society to manage flood Adur watercourses transport type informing Flood overwhelmed Transport where it is risk at the current estuary and overland affected (main awareness by catchment unacceptably level of flooding and along flow road, rail etc.) run-off high. (accepting that the coast flood risk will increase over time). Take further action to sustain current scale of flood risk Number of Tidal into the future residential influence Overtopping of (responding to the Property properties Land use extending River channel river potential increased (residential) affected and change up River embankments Reduce the in flood risk from cost of flood Adur cost of flood urban damage damages development, land where it is use change and unacceptably climate change). Number of high. commercial Take further action Urban Structural Roads and Property Property properties to reduce flood risk drainage blockages/ Online storage fields (commercial) affected and Support the (now and/or in the systems incapacity cost of flood implementation future). damage of sustainable planning Take action to Area of land policies taking Attenuation/ increase the affected and due regard of retention frequency of damages to flood risk. Floodplain flooding to deliver Agriculture agricultural storage benefits locally or (land land (wetland elsewhere, which resource) (according to creation) may constitute an Agricultural overall flood risk Land reduction (e.g. for Classification) habitat inundation). Area of Increase water Biodiversity wetland and retention within Agricultural – designated naturally active the catchments drainage resource floodplain where Rural land use Biodiversity Species appropriate. change Best farming

– species diversity practices Biodiversity - Restore rivers Habitat quality Afforestation habitats and floodplains Area of AONB to a naturally River Landscape and proposed functioning maintenance National Park state where feasible.

Environment Enhance the biodiversity of the catchment including the Amount of support of the disruption Increased Dredging/ Soil erosion national and caused by soil local conveyance desilting erosion biodiversity action plan (BAP) targets.

Reduce soil erosion. Removal of channel obstruction Defences, diversion channels, flood Protection alleviation measures schemes River

engineering Analysis and understanding Studies of groundwater flooding

Environment Agency River Adur CFMP - Appendix B (September 2008) 54 Form B4 CFMP policy option The following generic policy options have been recommended in the CFMP guidelines for consideration. They are intended to cover the whole spectrum of potential policy choices in response to flood risk. No active intervention (including flood warning and maintenance); continue to monitor and Option 1: advise. Reduce existing flood risk management actions (accepting that flood risk will increase over Option 2: time). Continue with existing or alternative actions to manage flood risk at the current level Option 3: (accepting that flood risk will increase over time). Take further action to sustain the current level of flood risk into the future (responding to Option 4: the potential increased in risk from urban development, land use change and climate change). Option 5: Take further action to reduce flood risk. Take action to increase the frequency of flooding to deliver benefits locally or elsewhere Option 6: (which may constitute an overall flood risk reduction, e.g. for habitat inundation).

Environment Agency River Adur CFMP - Appendix B (September 2008) 55

Policy unit 1 Upper Adur Policy appraisal forms Form B5 – Summary of current and future levels of and responses to flood risk. Form B6 – Appraisal of policy options against policy unit objectives. Form B7 – Summary of losses and gains. Form B8 – Summary of preferred policy. Form B9 – Requirements for further policy development and appraisal. Form B10 – Indicators for monitoring, review and evaluation.

Environment Agency River Adur CFMP - Appendix B (September 2008) 56

Form B5 Summary of current and future levels or and responses to flood risk Policy unit 1 - Upper Adur Defences: No major defence schemes. There are approximately 12km of raised tidal embankments on lower sections of the Adur East and Adur West Branches and some short lengths of culverted channel. In total there are approximately 25.5 km of raised defences in his policy unit.

Flood warning: This unit is covered by the River Adur East Branch (north Burgess Hill to Chates Weir, Henfield) and River Adur West Branch (Coolham to Current responses to flood risk Bines Green) Flood Warning Areas. There are around 20 properties connected within the policy unit to the flood warnings direct service.

Maintenance: We maintain the sections of flood embankment to the south of the unit. We also carry out an annual maintenance programme whereby much of the river lengths in the unit are subject to annual weed clearance to allow river flow. The estimated cost of maintaining the channels and existing defences under the Environment Agency’s responsibility is approximately £80,000. Standard of protection: The raised embankments to the lower sections of the Standards of service that apply Adur East and West Branches are considered to offer protection ranging from the to flood defences within the 20% annual probability event (1 in 5) to the 3.3% annual probability event (1 in policy unit 30). They are considered to be at or above the target condition. In 10% flood In 1% flood In 0.1% flood Receptors outline* outline* outline* Residential properties 2 5 N/A Commercial properties 0 0 N/A Population 5 12 N/A Property damages £93,530 £0.207 million N/A Agricultural damages £78,840 £0.126 million N/A A roads 0.42 km 0.68 km 2.92 km Railways 0 km 0 km 0.05 km Agricultural land Grade 2 2 2 0 km 0 km 0 km 1 Agricultural land Grade 2 2 2 0 km 0 km 0.10 km 2 Agricultural land Grade 2 2 2 1.91 km 3.06 km 3.61 km What is currently exposed to 3 flooding? Agricultural land Grade 2 2 2 5.57 km 12.13 km 13.88 km 4 Agricultural land Grade 2 2 2 0 km 0 km 0 km 5 SNCIs 0.28 km2 2.7 km2 3.32 km2 SSSI 0 km2 0 km2 0 km2 Listed Buildings 1 2 6 SM 0 0 3 AONB 0 km2 0 km2 0.12 km2 ESA 0 km2 0 km2 0 km2 Registered Historic 2 2 2 0km 0km 0.222km Parks and Gardens Proposed National Park 0.16 km2 2.96 km2 3.15 km2 * 10% and 1% based on broadscale model results and 0.1% based on Flood Zone 2 Economic and social receptors: Currently approximately five properties are at risk of fluvial flooding in the policy unit from the 1% annual probability fluvial flood event.

There are a few incidents of road disruption due to surface water run-off flooding. Who and what are currently A small number of isolated properties within the catchment may suffer from most vulnerable to flood disrupted access routes. damage and losses?

Very short sections of the A23(T), A24, A2037 and A281, a total of 0.68km, lie in the 1% annual probability flood event outline; increasing to a total length affected of approximately 3km in the more extreme flood events (Flood Zone 2).

Environment Agency River Adur CFMP - Appendix B (September 2008) 57 Only moderate to low grade agricultural land (Grades 3 and 4) is at risk of localised fluvial flooding.

Environmental designations: There are no internationally designated sites or SSSIs at risk of flooding within this policy unit.

Total area of 2.7km2 of the River Adur Water Meadows and Wyckham Wood SNCI is located within the 1% annual probability flood event outline in this policy unit. The sensitivity of this site to flooding is low and may benefit from periodic flooding.

Landscape: The High Weald AONB is located within this policy unit, however none of this area is located within the 1% annual probability flood event outline. The sensitivity of the site to flooding is low.

Natural and Historic Environment: Significant areas of existing wet woodland are located within the 1% annual probability flood outline, however these areas would benefit from increased flooding.

Two listed buildings are at risk of flooding during the 1% annual probability flood event, this increases to six within the extreme flood outline, including one parish church.

There is no extent of registered historic parks and gardens located within the 1% annual probability flood outline, however, a small extent of Knepp Castle and Heaselands is located within the extreme flood outline.

There are no SMs within the 1% annual probability flood event outline. This increases to three, two salterns located to the north of St. Peter’s church and Knepp Castle, within the extreme flood outline. What are the key factors that Flood risk not expected to significantly increase in the future. Some increase in could drive future flood risk? flood risk due to climate change (increased inflows) is predicted. What are the possible future Very small increase (approximately £0.01 million) in AAD due to climate change. levels of flood risk under the In 100 years approximately 6 properties at risk of flooding in the policy unit. main scenarios? There is potential to reduce flood risk downstream in other policy units by What potential responses (or providing flood storage within this policy unit and also through changes in land groups of responses) are use by reducing run-off in the catchment. Lowering or removing flood defences being considered to manage could also help reduce flood risk in this and other areas. In addition there is likely flood risk? to be environmental benefit to the River Adur Water Meadows and Wyckham Wood SNCI. There is currently some uncertainty about how effective land management and vegetation cover is in altering run-off at the catchment scale. It is known to work locally, but we do not yet know its effect on the catchment as a whole. What gaps and uncertainties are there in knowledge, and The broadscale modelling has shown that lowering or removing flood defences what assumptions have been can help reduce flood risk in this area. We will need more detailed studies to made? We have estimated the future increase in flood risk within this policy unit on the best available prediction we have of climate change, frequency and size of storms and flood events in the future.

The following tables provide a summary of how flooding may change in response to flood management options which may be adopted within the policy unit and what the implications of these changes might be. We have not applied any specific measures or schemes to the policy unit, but have applied what has been termed a ‘generic response’. This represents the most likely outcome of a given policy, but is not specific and does not reflect any proposed scheme or project. It simply allows a broad assessment of what the impact of that policy might be.

A broadscale model has been used to investigate the impact of these changes and has allowed us to quantify the effect on flood damages. The results given below for each of the generic responses and the basecase are for the 1% annual probability flood event.

Environment Agency River Adur CFMP - Appendix B (September 2008) 58

Generic response: Attenuation/retention (storage) on the Adur West Branch 1% annual probability fluvial flood Results from broadscale modelling damages (£m) The broadscale modelling has indicated that applying flood storage on the Adur West Branch (of no specific size or location) has a minor positive effect on flood damages within this policy unit (approximately £0.01 million decrease Future basecase = £0.424 in flood damages). The broadscale modelling has also shown a reduction in Generic response = £0.415 flood damages downstream in policy unit 3, with a 6% reduction in total flood damages from £3.71 million down to £3.48 million for the 1% annual % change = -2% probability fluvial flood event. Conclusions A large flood storage reservoir on the Adur West Branch will provide some benefit downstream by reducing flood damages. Although the benefit reduces further downstream in other policy units as the flooding becomes more dominated by the tide.

Generic response: Rural land use change – changing farming practices to reduce run-off rates 1% annual probability fluvial flood Results from broadscale modelling damages (£m) The effect of reducing run-off rates through changes in land use has been applied across the whole of this policy unit within the broadscale model. The results show a small reduction in flood damages within this policy unit of Future basecase = £0.424 approximately 3% for the 1% annual probability fluvial flood event. Reductions in flood damages are also experienced in policy unit 3 Generic response = £0.410 downstream, with a 6% reduction in total flood damages. The decrease in % change = -3% flood damages diminishes further downstream towards Shoreham and policy units 7 and 8. Conclusions Although the impact on flood risk from changing land use in the upper catchment is not large, it is nonetheless significant, both in this policy unit, and to a slightly larger extent, on policy unit 3, Steyning and Upper Beeding. Together with other downstream measures, land use change in the upper catchment can provide a useful way of reducing flood risk.

Generic response: Reducing the height of all raised embankments along the River Adur 1% annual probability fluvial flood Results from broadscale modelling damages (£m) Reducing the height of the raised embankments along the River Adur, from Shermanbury on the Adur East Branch and Bines Green on the Adur West Branch (in this policy unit) to the outfall into the sea at Shoreham, allows more frequent inundation of the floodplain on both sides of the river. This has the effect of increasing the flood extent in places, but significantly reducing the Future basecase = £0.424 depth of water in the river channel. The broadscale modelling has shown that reducing the height of the embankments has a relatively small impact on flood Generic response = £0.425 damages within this policy unit. % change = +0.2%

The reduction in flood damages resulting from this policy is more noticeable in policy unit 3, where the flood damages for the 1% annual probability fluvial flood event reduces by 37%. Conclusions The impact of reducing the height of the embankments is complex and far reaching, with the influence experienced within several policy units. By allowing more frequent flooding of the currently protected floodplains, there is less damage caused within this policy unit by the more frequent, but less severe flood events and minimal damage caused by the more extreme events. Downstream, the effect is reversed and the flood damages are reduced for the more extreme flood events in policy unit 3 and increased for the more frequent, less severe flood event. The increased inundation of the floodplains has the effect of reducing the peak water level in the river. This allows water to drain away more effectively, lowering water levels along the River Adur.

Environment Agency River Adur CFMP - Appendix B (September 2008) 59 Form B6 Appraisal of policy options against policy unit objectives Policy unit 1 – Upper Adur KEY = Scale of policy impact on objective: Not appraised Baseline Meets objective No impact Doesn’t meet objective Uncertain The preferred policy option is indicated below by the policy option highlighted in pink

Baseline (current Policy 1 Policy 2 Policy 3 Policy 4 Policy 5 Policy 6 and future)

No maintenance of watercourses. Channels become Improved land use blocked with management through vegetation and agri-environment Reduction in conveyance is schemes would maintenance of Improved level of reduced. reduce surface run-off watercourses. Improved level of channel maintenance Maintenance of the by woodland creation Channels become channel maintenance of watercourses with Current and future The height of raised channels continues. to increase blocked with vegetation of watercourses. increased conveyance baseline with current embankments would interception of run-off and conveyance is on the Adur East flood risk reduce over time. The flood warning Localised protection and increase reduced. branch. management. service remains in measures introduced. infiltration.

The flood warning place. The flood warning The flood warning The flood warning service is withdrawn. service is improved. There is potential to service remains in service is improved. increase water place. A do nothing retention by approach would introducing flood increase the flooding storage areas. Catchment Targets and Opportunities and in an unmanaged and objectives Indicators constraints unpredictable way. Economic objectives Ensure that river Targets Opportunities The current annual The level of river channel and flood Maintain a suitable - Improvements in the River channel and The level of river The level of river efficiency of channel and river channel and channel and flood defence maintenance balance of annual river No river channel and flood defence channel and flood channel and flood flood defence maintenance flood defence defence maintenance expenditure is channel and flood processes. flood defence maintenance defence maintenance defence maintenance maintenance River channel and expenditure is likely to appropriate to the defence maintenance - To work with Defra and maintenance expenditure remains expenditure will expenditure will farmers to produce soil expenditure is flood defence remain the same or be agricultural economic expenditure (£) to expenditure is at approximately increase over time to increase to be management plans which approximately maintenance slightly less than damage in rural areas annual average have a benefit to flood risk incurred as no £80,000. Annual mitigate the affects of significantly more £80,000; the annual expenditure reduces to £80,000 as agri- from flooding. damages from fluvial through reducing the run-off maintenance is average damages climate change to than £80,000. average damages be less than £80,000. environment schemes flooding to agriculture rate. undertaken. Annual from fluvial flooding to slightly more than Annual average Constraints from fluvial flooding to Annual average reduce the level of (£). average damages agriculture increase £80,000. Annual damages from fluvial - Available funding for the agriculture are damages from fluvial management required. initial set up of new flood risk from fluvial flooding to over time due to the average damages from flooding to agriculture currently around flooding to agriculture Annual average Indicators management schemes. agriculture increase affects of climate fluvial flooding to are estimated to be - Older flood defence £13,700, increasing to are likely to be around damages from fluvial Balance of annual river to be around change to be around agriculture will remain less than £2,000. The structures are likely to be around £18,200 in the £20,000. The balance flooding to agriculture channel and flood more costly to maintain. £23,000. The £18,200. The balance around £13,700. The balance of future. The current of expenditure to are likely to be slightly defence maintenance - Limited available information balance of of expenditure to balance of expenditure expenditure to balance of damages is less than £13,700. expenditure (£) to on surface water and expenditure to damages will become to damages will damages will be groundwater flood damages. expenditure to unacceptable. The balance of annual average damages is unacceptable over become unacceptable unacceptable with damages is expenditure to damages from fluvial unacceptable. time with increased over time with expenditure being considered damages will remain flooding to agriculture damages. increased expenditure. unjustifiably high. acceptable. acceptable. (£). Social objectives Ensure the impact of Targets Opportunities Approximately 12 No maintenance of Approximately 12 Improved channel - Investigate removal of flooding on people No significant increase Environment Agency owned people and 5 channels and Approximately 14 people and 5 maintenance, The increased and property does not in the number of people and maintained existing properties are at risk drainage networks It is likely that the people and 6 properties are likely to increased local frequency of flooding significantly increase or properties affected by raised defences to reinstate of localised fluvial would result in an number of people and properties are likely to be at risk of localised defence works and will be managed such the 1% annual the floodplain between flooding by the current increase in the properties at risk of be at risk of localised fluvial flooding by the upgrading of the that the number of in the future (for Partridge Green and probability fluvial flood Steyning and between 1% annual probability frequency, extent and localise fluvial flooding fluvial flooding by the current 1% annual drainage network and properties at risk in example due to event or surface water Steyning and Shoreham to a flood event. This depth of localised will increase to be current 1% annual probability flood event warning service will this policy unit is not climate change) in the flooding in the future naturally functioning state, to increases to around fluvial flooding. more than 14 and 6 probability flood event reduce the number of increased from the Upper Adur. provide flood storage and enhance conservation value 14 and 6 in the future. respectively. Coverage of Flood people affected by current baseline and Indicators and biodiversity. The number of The current level of Warning Service is localised fluvial the Number of people and Constraints An estimated 9 people and properties The current level of Flood Warning increased, system is flooding to less than Flood Warning properties affected by - Government and properties are at risk of localise Flood Warning Service Service remains in improved in terms of 10 and number of Service is retained at international legislation, the 1% annual environmental management currently covered by a fluvial flooding will remains in place. place. accuracy and properties affected to the current level. probability fluvial flood policies, plans and strategies flood warning service. increase to be more coverage. less than 4.

Environment Agency River Adur CFMP - Appendix B (September 2008) 60 event for the catchment must be than 20 and 48 complied with, such as accommodating new housing respectively. Flood Warning Coverage of Flood within the catchment as Service is improved Warning Service detailed by the South East Withdrawing the flood in terms of accuracy Plan and compliance with the warning system may and coverage Habitats Directive. result in increased

risk to human life. Environmental objectives Opportunities - Enhance the character of the landscape and increase amenity opportunities for recreation, tourism and leisure activities. - Move toward more natural rivers and drainage networks, as outlined within PPS25, will mean we can achieve more efficient and sustainable water management, whilst enhancing landscape character. - Investigate removal of Environment Agency owned and maintained existing raised defences to reinstate the floodplain between Partridge Green and Steyning to a naturally Currently there is functioning state, to provide approximately 26km of No maintenance and flood storage and enhance defended watercourse reduction in the conservation value and 2 Restoring the rivers to and around 4km of height of biodiversity. A reduction in a naturally functioning - Help meet national naturally active embankments would Targets maintenance would Increasing state and increasing biodiversity action plan (BAP) floodplain in this policy allow the channel and Increase the length of targets. allow the channel and It is not expected that There is unlikely to be conveyance on the floodplain connectivity unit. There are floodplain to function naturally functioning Constraints floodplain to function the river processes or any significant Adur East branch is could be achieved - Government and opportunities now and more naturally and river and area of more naturally and floodplain connectivity alterations to the river likely to reduce the through this policy international legislation, in the future to restore the natural naturally active environmental management restore the natural river will significantly processes and natural river option and provide enhance the floodplain river processes (i.e. Restore parts of the floodplain along the Rive policies, plans and strategies processes (i.e. erosion change under this floodplain connectivity processes and flood storage. connectivity along erosion and River Adur and Adur upstream of for the catchment must be and deposition). policy option. under this policy floodplain complied with, such as defended parts of the deposition). floodplain to a naturally Steyning and Upper However, this would option. connectivity. The length of naturally accommodating new housing River Adur, for However, this would functioning state where Beeding, providing within the catchment as occur in an unmanaged The length of naturally functioning river is example by restoring it occur in an feasible upstream of suitable quality habitat. detailed by the South East and unpredictable way. functioning river may The length of naturally The length of likely to increase by Plan and compliance with the back to its original unmanaged and Steyning and Upper slightly increase over functioning river is naturally functioning up to 26km and the Habitats Directive. state or removing unpredictable way. Beeding. Indicators - Some environmentally The length of naturally time from the current likely to remain at the river is likely to area of naturally active raised embankments. Length of naturally designated habitats are functioning river is extent and the area of current extent and the decrease from the floodplain to up to The length of 2 functioning river (km). susceptible to changes in likely to increase by naturally active area of naturally active current extent and 12km . flood frequency, floodwater With current flood risk naturally functioning chemistry, groundwater around 10km and the floodplain to slightly floodplain is likely to the area of naturally management in the river is likely to 2 2 Area of naturally active levels and drainage system area of naturally active more than 4km . remain at around 4km . active floodplain will This would be 2 future the length of increase by around 2 floodplain (km ). maintenance. floodplain to around be less than 4km . achieved in a - Existing urban development naturally functioning 26km and the area of 2 7km . managed and may prevent reinstatement of river and naturally naturally active natural river processes. controlled way. active floodplain may floodplain to - Individual homes and 2 properties are currently at slightly increase over approximately 12km . risk of flooding. time. - Presence of protected species with specific water level, water quality and habitat requirements. - Changes to flood risk management can affect the landscape, its character and value as an amenity. - Historic development and some heritage designations in Steyning, Bramber and Upper Beeding present permanent physical obstructions. - Location of electricity pylons adjacent to the Lower River Adur (currently protected by existing defences). - No degradation of existing fish passage and habitat.

Environment Agency River Adur CFMP - Appendix B (September 2008) 61 Opportunities - Help meet national biodiversity action plan (BAP) targets. - Investigate removal of Environment Agency owned and maintained existing raised defences to reinstate the floodplain between Partridge Green and Steyning to a naturally functioning state, to provide flood storage and enhance conservation value and biodiversity. Constraints Doing nothing and - Some environmentally removing designated habitats are embankments would Reducing the susceptible to changes in flood frequency, floodwater allow the rivers to maintenance of the Increasing chemistry, groundwater flood more frequently channels would conveyance on the levels and drainage system and increase the eventually allow the There would be a Adur East branch is maintenance. There is currently 2.7 2 flood depths, rivers to flood more slight increase to likely to reduce the Targets - Changes to flood risk km of the SNCI 2 increasing the area of frequently and increase approximately 3 km The extent of the SNCI extent of flooding and Increasing the flood Protect and enhance the management can affect the located within the 1% landscape, its character and the SNCI within the the flood depths, in the area of the within the 1% annual therefore the extent storage areas in this River Adur Water annual probability value as an amenity. 1% annual probability increasing the area of SNCI within the 1% probability flood event of the SNCI within the policy unit would Protect and enhance the Meadows and Wyckham flood event outline. flood outline to the SNCI within the 1% annual probability outline will remain at 1% annual probability improve the potential River Adur Water Wood Site of Nature 2 significantly more annual probability flood flood event outline due approximately 2.7 km . flood outline to less to increase the area of Meadows and Wyckham Conservation This is likely to 2 than 3 km2. outline to more than 3 to the affects of than 2.7 km . SNCI to more than 3 Wood Site of Nature Importance. increase to around 3 2 2 2 km . climate change. There will be no km and improve or Conservation km in the future, There is increased notable change in the Decrease in flooding increase the habitat Importance. Indicators however, there will be potential to There is increased However, as the habitat and species extent (duration and types and species Habitat quality and no notable increase in significantly improve potential to improve or increase is small there diversity within the depth) will reduce the diversity in a managed species diversity. habitat and species or increase the increase the habitat will be no notable SNCI. potential of and controlled way. diversity with such a habitat types and types and species increase in habitat and increasing habitat minor increase. species diversity diversity within the species diversity. types and species within the SNCI. SNCI. However, this diversity within the However, this would would occur in an SNCI. occur in an unmanaged way. unmanaged and uncontrolled way.

Environment Agency River Adur CFMP - Appendix B (September 2008) 62 Opportunities - Help meet national biodiversity action plan (BAP) targets. Currently none of the - Work with the High Weald High Weald AONB is AONB Joint Advisory located within the 1% Committee to achieve the The area of the South targets set in the High Weald annual probability The area of the South Downs proposed AONB Management Plan to flood event outline. The area of the South Downs proposed maximise the opportunities National Park located The area of the South This remains the case Downs proposed The area of the South National Park located for natural processes to within the 1% annual Downs proposed in the future. National Park located Downs proposed within the 1% annual Targets reduce flooding through the probability flood National Park located adoption of river restoration within the 1% annual National Park located probability flood Increase the landscape 2 event outline within the 1% annual policies, whilst enhancing Approximately 2.9km probability flood event within the 1% annual event outline The landscape character value of the landscape character. increases to be probability flood event of the South Downs outline increases over probability flood event decreases to be character of the South High Weald AONB and - Investigate removal of significantly more outline increases to be Increase the landscape Environment Agency owned proposed National 2 2 time to at around outline remains at minimal. Downs proposed South Downs proposed than 3.1km . more than 3.1km . 2 2 character value of the and maintained existing Park is located within 3.1km . around 2.9km . National Park would National Park. raised defences to reinstate High Weald AONB and the current 1% annual A decrease in be enhanced with the the floodplain between The landscape The landscape proposed South Downs probability flood event There would be no There would be no flooding extent, depth implementation of Indicators Partridge Green and character of the character of the South National Park. Steyning to a naturally outline. This notable impact on the impact on the and frequency is considered flood risk Landscape character South Downs Downs proposed functioning state, to provide increases over time to landscape character landscape character of likely to have a management assessment of the flood storage and enhance 2 proposed National National Park is likely approximately 3.1km of the High Weald the High Weald AONB negative impact on practices. AONB and proposed conservation value and Park is likely to alter to alter in a beneficial biodiversity. in the future. AONB or South or South Downs the landscape National Park. in a beneficial manner, however, it will Constraints Downs proposed proposed National Park character of the - Some environmentally manner, however, it occur in an unmanaged The landscape National Park in this in this policy unit. South Downs designated habitats are will occur in an way. character of the South policy unit. proposed National susceptible to changes in unmanaged and un flood frequency, floodwater Downs proposed Park controlled way. chemistry, groundwater National Park is levels and drainage system maintenance. unlikely to notable - Changes to flood risk alter. management can affect the landscape, its character and value as an amenity. Impact uncertain - Impact uncertain - Reduction in Risk downstream Risk downstream Reduction in Reduction in Risk downstream conveyance and may increase due to will increase due to Does this policy change flood risk locally or elsewhere: conveyance may conveyance may will increase due to increased storage improved improved benefit downstream benefit downstream climate change will benefit conveyance conveyance areas areas downstream areas

Environment Agency River Adur CFMP - Appendix B (September 2008) 63 Form B7 – Summary of losses and gains.

Policy unit Policy Unit 1 - Upper Adur name/number:

Preferred policy Policy options Losses Gains option relative to current baseline Policy option P1 Environmental NO LOSSES MEDIUM+ Not preferred option – Although the benefits to The length of naturally the environment are functioning river and potentially high, area of naturally active alterations to natural floodplain along the habitats, biodiversity, upper River Adur will river and floodplain increase by functions and landscape approximately 26km 2 will be unmanaged and and 8km respectively uncontrolled and but in an unmanaged therefore unpredictable. and unpredictable way In addition to this, the The area of the River AAD to agricultural land Adur Meadows and resulting from this policy Wyckham Wood SNCI will be unacceptably will significantly high. increase by more than 0.3km2 but in an unmanaged and

uncontrolled way The landscape value of the South Downs

proposed National Park is likely to be beneficially altered but

in an unmanaged and uncontrolled way

Social Medium - NO GAINS

The number of people and property at risk

significantly increases and the withdrawal of flood warning services

further increases flood risk

Economic HIGH- NO GAINS

The balance of FRM expenditure to AAD compared to other policy options is unacceptable with AAD to agricultural land increasing by approximately £9,300 Policy option P2

Environment Agency River Adur CFMP - Appendix B (September 2008) 64 Environmental NO LOSSES MEDIUM+ Not preferred option – Although the benefits to The length of naturally the environment are functioning river and potentially relatively area of naturally active high, alterations to floodplain along the natural habitats, upper River Adur will biodiversity, river and increase by floodplain functions and approximately 10km 2 landscape will be and 3km respectively unmanaged and but in an unmanaged therefore unpredictable. way In addition to this, the The area of the River AAD to agricultural land Adur Meadows and resulting from this policy Wyckham Wood SNCI will be unacceptably will increase by more 2 high. than 0.3km but in an unmanaged way The landscape value

of the South Downs proposed National Park is likely to be

beneficially altered but in an unmanaged way

Social LOW- NO GAINS The number of people

and property at risk

significantly increases and flood warning

services is only

maintained at its current level

HIGH- Economic NO GAINS The balance of FRM

expenditure to AAD is unacceptable compared to other policy options with AAD to agricultural land increasing by approximately £6,300 Policy option P3 Environmental NO LOSSES LOW+ Not preferred option – The potential benefits in The length of naturally terms of the functioning river and environment are not area of naturally active sufficiently optimised floodplain along the under this policy. In upper River Adur will addition to this, the AAD be slightly increased to agricultural land will The area of the River increase significantly in Adur Meadows and the future. Wyckham Wood SNCI will slightly increase but with no notable

increase in biodiversity The area of the South Downs proposed

National Park that falls Environment Agency River Adur CFMP - Appendix B (September 2008) 65 within the 1% AEP will increase slightly but

with no notable increase in landscape value

Social LOW- NO GAINS

The number of people and property at risk

significantly increases and flood warning services is only

maintained at its current level

HIGH- Economic NO GAINS The balance of FRM expenditure to AAD will become unacceptable compared to other policy options in the future with AAD increasing by approximately £4,500 Policy option P4 Environmental LOW- LOW+ Not preferred option – Although AAD to The length of naturally The area of the River agricultural land will not functioning river and Adur Meadows and increase in the future, area of naturally active Wyckham Wood SNCI opportunities to bring floodplain along the will remain the same benefits to the upper River Adur will with no increases in environment are not remain the same biodiversity sufficiently optimised The area of the South under this policy and Downs proposed NP there are also potential that falls within the 1% losses in terms of AEP remain the same landscape value and with no increase in floodplain function. landscape value

Social NO LOSSES LOW+

The number of people and property at risk

does not significantly increase and flood warning services are

improved

Economic MEDIUM- NO GAINS

The balance of FRM expenditure to AAD will become unacceptable in the future with necessary increases in FRM expenditure to keep AAD to agricultural land constant

Environment Agency River Adur CFMP - Appendix B (September 2008) 66 Policy option P5 Environmental MEDIUM- NO GAINS Not preferred option – There are no gains The length of naturally under this policy option. functioning river and FRM expenditure is area of naturally active unacceptably high and floodplain along the there will be significant upper River Adur will be negative impacts on the slightly decreased environment. The area of the River Adur Meadows and

Wyckham Wood SNCI will be decreased The area of the South

Downs proposed NP that falls within the 1% AEP will be decreased

which will impact negatively on the landscape value

Social NO LOSSES LOW+

The number of people and property at risk

does not significantly increase and flood warning services are

improved

Economic MEDIUM- NO GAINS

The balance of FRM expenditure to AAD will become unacceptable in the future with necessary increases in FRM expenditure to reduce AAD to agricultural land Policy option P6 Environmental NO LOSSES HIGH+ Preferred Policy Option – There are no losses The length of naturally under this policy option. functioning river and The potential benefits to area of naturally active the environment in floodplain along the terms of natural habitat, upper River Adur will biodiversity, river and increase by floodplain function and approximately 26km 2 landscape value are and 8km respectively, maximised and will be in a managed and carried out in a controlled way managed and controlled The area of the River way which will in turn Adur Meadows and optimise the balance Wyckham Wood SNCI between FRM and AAD will significantly to agricultural land. increase by more than 2 Encouraging increased 0.3km but in a uptake of agri- managed and environment schemes controlled way Environment Agency River Adur CFMP - Appendix B (September 2008) 67 The landscape value will further reduce the of the South Downs AAD to land.

proposed National Implementing policy Park will be enhanced option 6 in this part of in a managed and the catchment will also

controlled way bring strategic benefits to policy units downstream through Social NO LOSSES LOW+ increased floodwater The number of people storage. and property at risk

does not significantly increase and flood warning services are

maintained

Economic NO LOSSES HIGH+ The balance of FRM expenditure to AAD will remain acceptable with reductions in FRM expenditure and AAD to agricultural land due to agri-environment schemes and targeted FRM

Environment Agency River Adur CFMP - Appendix B (September 2008) 68 future risk would need to be low so that the residual risk after a neutral policy was implemented remained acceptable, and/or; (iii) no additional social, economic and/or environmental gains or losses. Policy options may also be ‘neutral’ where they are not relevant in a particular policy unit, or where it is not feasible for a policy option to contribute to an objective. HIGH: High positive A policy has a ‘high positive’ effect where it could contribute to a social, economic or environmental objective in a significantly positive way. A ‘high positive’ effect could be: (i) a very large reduction in current flood risk; (ii) avoiding/reducing very large projected increases in flood risk under future conditions, and/or; (iii) significant additional social, economic and/or environmental gains. MEDIUM: Medium positive A policy has a ‘medium positive’ effect where it could contribute to a social, economic or environmental objective in a positive way. A ‘medium positive’ effect could be: (i) a reduction in current flood risk; (ii) avoiding/reducing projected increases in flood risk under future conditions, and/or; (iii) additional social, economic and/or environmental gains. LOW: Low positive A policy has a ‘low positive’ effect where it could make a limited contribution to a social, economic or environment objective, but where the overall contribution would be positive. A ‘low positive’ effect could be: (i) an overall reduction in current flood risk; (ii) an overall avoidance/reduction in flood risk under future conditions,

Environment Agency River Adur CFMP - Appendix B (September 2008) 69

Form B8 Summary of preferred policy Policy unit 1 - Upper Adur Physical characteristics: - Largely rural landscape in the north of the CFMP area, of moderate agricultural quality with a few villages and isolated properties. - Weald Clay Formation geology set predominantly in the Low Weald Landscape Character Area, with poorly draining clay soils, which may result in rapid run-off from the land. - The north-east section (High Weald AONB) has varied topography, and this region and the southern boundary of the unit overlie sandstone geology. - The East and West Adur confluence lies west of Henfield village amongst gently sloping land, which results in slow run-off from the land. - The Adur West Branch headwaters emerge north of Coolham. - The northern section of the proposed South Downs National Park designation is present in the far south of the unit. - Flood defences extend to Bines Green on the Adur West Branch and Shermanbury on the Adur East Branch. Flood mechanism: - Low fluvial flood risk (some localised areas of fluvial flooding). - Adur West Branch slower response to run-off rates than the Adur East Branch. Receptor: - Mainly moderate grade Agricultural Land (Grades 3 and 4) at risk of localised fluvial Problem/risk flooding. - Limited environmental and landscape designations – only High Weald AONB (which is outside of floodplain) and the proposed South Downs National Park. - Significant areas of existing wet woodland, which would benefit or be increased in area through increased flooding. - Small number of isolated properties within the River Adur floodplain. - Currently approximately 5 properties at risk of fluvial flooding in the policy unit from the 1% annual probability fluvial flood event. - In 100 years approximately 6 properties at risk of flooding in the policy unit. Current Flood Risk Summary Number of properties at risk of flooding (1% annual probability flood event) 5 Total damages (approx.) (1% annual probability flood event) £0.333 million Annual average damages (approx.) £38,000 Future Flood risk: - An increase in the severity of flooding does not significantly increase the risk of flooding or significantly increase the economic damages. - Flood risk is currently assessed as low, assessment remains low in the future. Future Flood Risk Summary (in 100 years time) Number of properties at risk of flooding (1% annual probability flood event) 6 Total damages (approx.) (1% annual probability flood event) £0.424 million Annual average damages (approx.) £49,000 Policy 6 - Take action to increase the frequency of flooding to deliver benefits locally or Policy selected elsewhere, which may constitute an overall flood risk reduction (for example for habitat inundation). This policy can deliver benefits for people and the environment locally or in other policy units. By increasing flooding locally in this unit or at least keeping water in the catchment for longer, flooding downstream can be reduced, and in many instances, increasing flooding can improve wetland biodiversity, as flooding is an essential part of floodplain ecosystems. Current management and maintenance activities include maintaining defences, grass and weed cutting, debris removal cutting back overhanging branches. Policy 6 sets a framework that actively supports increased flooding, or keeping water on the land for longer. This applies to this policy unit for the following reasons: Justification - An increase in flooding or retaining flood water for longer in this unit, reduces flood risk to properties in Steyning, Upper Beeding and Shoreham 100 years in the future. - An increase in flooding or retaining flood water for longer in this unit, reduces economic damages, from a 1% annual probability fluvial flood event 100 years in the future in Steyning and Upper Beeding, by approximately 6%. - An increase in flooding or retaining flood water for longer in this unit, also reduces economic damages, from a 1% annual probability fluvial flood event 100 years in the future locally in this policy unit, by approximately 3%. - An increase in flooding could result in an increase of approximately 1300 hectares of

Environment Agency River Adur CFMP - Appendix B (September 2008) 70 wetland around the River Adur Water Meadow and Wyckham Wood SNCI. This will improve local biodiversity and help meet biodiversity action plan targets. - There are relatively few constraints in this policy unit, such as environmental or landscape designations which would restrict options to increase flooding locally. - Ensure that river channel and flood defence maintenance expenditure is appropriate to the agricultural economic damage in rural areas from flooding. - Restore parts of the River Adur and floodplain to a naturally functioning state where Catchment feasible upstream of Steyning and Upper Beeding. objectives - Protect and enhance the River Adur Water Meadows and Wyckham Wood Site of Nature Conservation Importance. - Increase the landscape character value of the High Weald AONB and proposed South Downs National Park. Opportunities: - Improvements in the efficiency of channel and flood defence maintenance processes. - To work with Defra and farmers to produce soil management plans which have a benefit to flood risk through reducing the run-off rate. - Enhance the character of the landscape and increase amenity opportunities for recreation, tourism and leisure activities. - Move towards more natural rivers and drainage networks, as outlined within PPS25, will mean we can achieve more efficient and sustainable water management, whilst enhancing landscape character. - Investigate removal of Environment Agency owned and maintained existing raised defences to reinstate the floodplain between Partridge Green and Steyning to a naturally functioning state, to provide flood storage and enhance conservation value and biodiversity. - Help meet national biodiversity action plan (BAP) targets. - Work with the High Weald AONB Joint Advisory Committee to achieve the targets set in the High Weald AONB Management Plan to maximise the opportunities for natural processes to reduce flooding through the adoption of river restoration policies, whilst enhancing landscape character.

Catchment-wide Constraints: opportunities - Available funding for the initial set up of new flood risk management schemes. and constraints - Older flood defence structures are likely to be more costly to maintain. - Limited available information on surface water and groundwater flood damages. - Government and international legislation, environmental management policies, plans and strategies for the catchment must be complied with, such as accommodating new housing within the catchment as detailed by the South East Plan and compliance with the Habitats Directive. - Some environmentally designated habitats are susceptible to changes in flood frequency, floodwater chemistry, groundwater levels and drainage system maintenance. - Existing urban development may prevent reinstatement of natural river processes. - Individual homes and properties are currently at risk of flooding. - Presence of protected species with specific water level, water quality and habitat requirements. - Changes to flood risk management can affect the landscape, its character and value as an amenity. - Historic development and some heritage designations in Steyning, Bramber and Upper Beeding present permanent physical obstructions. - Location of electricity pylons adjacent to the Lower River Adur (currently protected by existing defences). - No degradation of existing fish passage and habitat. Policy 1 - do nothing. Although this could be considered as a possible policy option, and would have a similar long-term result as policy 6, the effects would happen in an unmanaged and unpredictable way, and local flood risk may increase.

Policy 2 - reduce current level of flood risk management. This could also be considered a possible policy option for this area, and it could allow increased floodplain inundation whilst Alternative controlling the changes that would happen in time. This policy would not provide the benefits policies of reducing flood risk downstream or the benefits of increasing biodiversity that would occur considered through a managed approach to increasing flooding through policy 6.

Policy 3 - maintain current level of flood risk management. This option results in the least favourable result, with moderate increases in damages locally of approximately 30% but with none of the benefits that would come from a managed approach of potentially increasing areas of wetland and therefore improving local biodiversity and help meet biodiversity action plan targets. Environment Agency River Adur CFMP - Appendix B (September 2008) 71

Policy 4 - maintain the current level of flood risk into the future. This policy could apply to this policy unit, but it implies a need for increased flood risk management in the future and does not consider the opportunity for large potential reduction in flood risk elsewhere. Although there is a 30% increase in flood risk in the future the assessment of flood risk remains low, with approximately 6 properties at risk under future scenarios.

Policy 5 - reduce the level of flood risk, both now and in the future. As the current and future flood risk in this unit is low, there is no justification for investing in flood defences to reduce flood risk. There is currently some uncertainty about how effective land management and vegetation cover is in altering run-off at the catchment scale. It is known to work locally, but we do not Uncertainties yet know its effect on the catchment as a whole. and dependencies The broadscale modelling has shown that lowering or removing flood defences can help reduce flood risk in this area. We will need more detailed studies to find out if it is practical to do this and improve the environment at the same time.

Environment Agency River Adur CFMP - Appendix B (September 2008) 72 Form B9 Requirements for further policy development and appraisal Policy unit 1 - Upper Adur Is there a need for further policy development? No If yes, then mark policy options for more detailed development. Some complex policies may require more detailed development, probably at Strategy Plan level. Is there a need for further more detailed appraisal? Yes If yes, take forward to strategy study.

Environment Agency River Adur CFMP - Appendix B (September 2008) 73

Form B10 Indicators for monitoring, review and evaluation This form sets out the indicators that need to be included in the policy implementation plan, for policy monitoring, drawing on the residual risks and likely impacts identified above. This will allow better review and evaluation of the policy when implemented. Policy unit 1 – Upper Adur Indicators to be included in policy unit 1 implementation plan are:

Economic - Balance of annual river channel and flood defence maintenance expenditure (£) to annual average damages from fluvial flooding to agriculture (£). - Flood damages downstream in policy unit 3 (Steyning and Upper Beeding) (£AAD).

Social - Number of people affected by the 1% annual probability flood event downstream in policy unit 3 (Steyning and Upper Beeding).

Environmental - Length of naturally functioning river (km). - Area of naturally functioning floodplain (km2). - Habitat quality and species diversity. - Landscape character assessment of the AONB and proposed National Park.

Environment Agency River Adur CFMP - Appendix B (September 2008) 74

Policy unit 2 Burgess Hill Policy appraisal forms Form B5 – Summary of current and future levels of and responses to flood risk. Form B6 – Appraisal of policy options against policy unit objectives. Form B7 – Summary of losses and gains. Form B8 – Summary of preferred policy. Form B9 – Requirements for further policy development and appraisal. Form B10 – Indicators for monitoring, review and evaluation.

Environment Agency River Adur CFMP - Appendix B (September 2008) 75

Form B5 Summary of current and future levels or and responses to flood risk Policy unit 2 – Burgess Hill Defences: There are no formal raised defences within this policy unit. Flood risk management activity consists of carrying out channel maintenance programme; completing annual weed cuts and desilting structures when necessary.

Flood warning: This policy unit contains the upper section of the Adur East Branch Flood Warning Area. There is a lead time of 2 hours, but there is a flashy Current responses to flood risk response to heavy rainfall due to upper catchment topography and urban areas. within the policy unit There are no properties connected to the flood warnings direct service.

Maintenance: The most upstream reach is inspected every 24 months. There is a significant build up of gravel in the channel at Hag Bridge, this is removed in order to provide more accurate flood warning. The estimated current annual cost of maintaining the channels and structures under the Environment Agency’s responsibility is approximately £50,000. Standards of service that apply Standard of protection: There is no formal standard of protection from fluvial to flood defences within the flooding as there are no formal raised defences. policy unit In 10% flood In 1% flood In 0.1% flood Receptors outline* outline* outline* Residential properties 2 12 539 Commercial properties 0 1 40 Population 5 30 1290 Property damages 0 £0.109 million N/A Agricultural damages £560 £1,900 N/A A roads 0.02 km 0.04 km 0.4 km Railways 0 km 0 km 0.26 km Agricultural land Grade 1 0 km2 0 km2 0 km2 Agricultural land Grade 2 0 km2 0 km2 0 km2 What is currently exposed to Agricultural land Grade 3 0.01 km2 0.05 km2 0.77 km2 flooding? Agricultural land Grade 4 0.07 km2 0.15 km2 0.34 km2 Agricultural land Grade 5 0 km2 0 km2 0 km2 SNCIs 0 km2 0 km2 0.04 km2 SSSI 0 km2 0 km2 0.001 km2 Listed Buildings 0 0 2 SM 0 0 0 AONB 0 km2 0 km2 0.01 km2 ESA 0 km2 0 km2 0 km2 Registered Historic Parks 2 2 2 and Gardens 0 km 0 km 0 km Proposed National Park 0 km2 0 km2 0.004 km2 * 10% and 1% based on broadscale model results and 0.1% based on Flood Zone 2 Economic and social receptors: Currently approximately 13 properties and 30 people at risk of fluvial flooding in the policy unit from the 1% annual probability fluvial flood event. Significantly more properties are at risk from surface water and localised urban flooding.

A small area of industrial estate and agricultural land in Burgess Hill and Hassocks.

Only moderate to low grade agricultural land (Grades 3 and 4) is at risk of Who and what are currently localised fluvial flooding. most vulnerable to flood damage and losses? Some local minor roads are at risk of flooding during the 1% annual probability flood event.

Environmental designations: There are no internationally or nationally designated sites or SSSIs at risk of flooding for the 1% annual probability flood event within this policy unit.

There is a very small area, less than 0.005km2, of the Bedelands SNCI located within the 1% annual probability flood event outline in this policy unit. The sensitivity of this site to flooding is low and may benefit from periodic flooding. Environment Agency River Adur CFMP - Appendix B (September 2008) 76

Landscape: The proposed South Downs National Park is located within this policy unit, however none of this area is located within the 1% annual probability flood event outline. The Sussex Downs AONB bounds the southern border of this policy unit.

Natural and Historic Environment: There are no listed buildings located within the1% annual probability flood outline; this increases to two within the extreme flood event outline, including one Baptist Chapel.

There are no registered historic parks and gardens or SMs located in this policy unit.

Areas of wet woodland within this policy unit benefit from periodic flood events. What are the key factors that Climate change (increased rainfall) and pressures for further urban development. could drive future flood risk? Annual average damages will more than double due to climate change.

In 100 years approximately 250 properties are at risk of flooding in the policy unit What are the possible future from the 1% annual probability fluvial flood event. levels of flood risk under the main scenarios? The scale of disruption is expected to increase slightly, and there is an increased probability of local minor roads flooding as a result of surface water flooding and/or urban drainage flooding causing localised flooding in areas of Burgess Hill and Hassocks. What potential responses (or There is potential to limit increased run-off from new development by installation groups of responses) are of SuDS. There is also potential to provide integrated urban drainage solutions to being considered to manage reduced urban flooding. The prevention of vulnerable development in flood risk flood risk? areas. We have estimated the future increase in flood risk within this policy unit on the best available prediction we have of climate change, frequency and size of What gaps and uncertainties storms and flood events in the future. are there in knowledge, and what assumptions have been Delivering this policy will partly depend on developing and implementing an made? effective urban drainage strategy in partnership with the local drainage authority, highway department, water and sewerage company and other relevant authorities or responsible parties.

The main sources of flooding for this policy unit are surface water, urban drainage and insufficient capacity of small streams. We have not been able to model these processes. However, we have been able to model the river process and the following tables provide a summary of how flooding may change in response to flood management options for fluvial flooding, which may be adopted within the policy unit and what the implications of these changes might be. We have not applied any specific measures or schemes to the policy unit, but have applied what has been termed a ‘generic response’. This represents the most likely outcome of a given policy, but is not specific and does not reflect any proposed scheme or project. It simply allows a broad assessment of what the impact of that policy might be.

Environment Agency River Adur CFMP - Appendix B (September 2008) 77 Generic response: Increasing conveyance on the Adur East Branch 1% annual probability fluvial flood Results from broadscale modelling damages (£m) The broadscale modelling has indicated that by increasing conveyance in the whole of the Adur East Branch, the extent of local flooding can be reduced Future basecase = £0.236 quite significantly. There is a 77% reduction in the 1% annual probability Generic response = £0.055 fluvial flood event damages. Annual average damages can also be reduced by 77%. % change = -77% Conclusions Although in practice it is quite difficult to achieve, improving the flow through the Adur East Branch, by whatever means, has been shown to reduce flood risk from fluvial flooding in Burgess Hill and Hassocks.

Generic response: Rural land use change – changing farming practices to reduce run-off rates 1% annual probability fluvial flood Results from broadscale modelling damages (£m) The effect of reducing run-off rates through changes in land use has been applied across the upper catchments of the River Adur. The results show a Future basecase = £0.236 significant reduction in flood damages within this policy unit of 62% for the 1% Generic response = £0.089 annual probability fluvial flood event and a 67% reduction in the average annual damages. % change = -62% Conclusions The reduction in run-off rates by changes in farming practices has shown a significant reduction in flood damages in this policy unit. However, flooding in this policy unit occurs from a number of processes so in practice the reduction in flood damages is unlikely to be as significant as the modelling has suggested, but together with other measures, land use change in the upper catchment can provide a useful way of reducing flood risk.

Environment Agency River Adur CFMP - Appendix B (September 2008) 78 Form B6 Appraisal of policy options against policy unit objectives Policy unit 2 – Burgess Hill KEY = Scale of policy impact on objective: Not appraised Baseline Meets objective No impact Doesn’t meet objective Uncertain The preferred policy option is indicated below by the policy option highlighted in pink

Baseline (current Policy 1 Policy 2 Policy 3 Policy 4 Policy 5 Policy 6 and future)

No maintenance of watercourses. Channels become Reduction in blocked with Improved level of maintenance of vegetation and channel maintenance watercourses. conveyance is of watercourses. Channels become Improved level of reduced. Maintenance of the blocked with channel maintenance channels continues. The flood warning vegetation and of watercourses. The flood warning service is improved. conveyance is service is withdrawn. The flood warning Localised protection Current and future reduced. service remains in measures introduced. Increase the local Not considered baseline with current No maintenance place. The flood warning defence works. feasible in this policy flood risk The flood warning undertaken on service is improved. unit. management. service remains in surface water and Maintenance of the Upgrade of surface place. urban drainage surface water and urban Improvements to the water and urban

networks. drainage networks surface water and drainage networks to Reduced level of continue. urban drainage increase capacity and maintenance of the A do nothing networks. meet design surface water and approach would standards for the urban drainage increase the flooding future. networks. in an unmanaged Catchment Targets and Opportunities and and unpredictable objectives Indicators constraints way. Economic objectives Ensure flood damages Targets Opportunities - Provide development control do not significantly No significant increase advice to ensure no increase increase in Burgess Hill in damages in Burgess in run-off from the new and Hassocks due to Hill and Hassocks from development proposed in the The current total future change (urban fluvial, surface water South East Plan (e.g. Burgess Hill). annual average development and and urban drainage - Reduce flood risk and damages from fluvial climate change). flooding due to future improve water quality by No maintenance of flooding and As channels and changes (urban promoting and encourage channels and Improved channel Improved channel estimated damages drainage networks development and the use of SuDS in the drainage networks The total annual maintenance, drainage maintenance, proposed urban resulting from surface decrease in capacity climate change). would lead to a average damages from networks and localised increased local developments in Burgess water flooding are and condition due to Hill. significant increase in fluvial flooding and protection measures defence works and approximately £4,300 reduced maintenance Indicators - Potential for improving the flooding with total estimated damages will mitigate the affects upgrading of the current defences, for and less than £60,000 the total annual Total annual average annual average resulting from surface of climate change. The drainage network example possible installation respectively. average damages from damages (to properties of demountable or temporary damages from fluvial water flooding will total annual average would reduce total fluvial flooding and Not applicable. and agriculture) from defences in Shoreham and flooding and increase over time due damages from fluvial annual average This increases to estimated damages fluvial flooding (£AAD). Burgess Hill. estimated damages to the affects of climate flooding and estimated damages from fluvial Constraints around £80,000 for resulting from surface resulting from surface change to be around damages resulting from flooding and the - Government and total annual average water flooding will Estimated* damages international legislation, water flooding being £80,000 and between surface water flooding estimated damages damages from fluvial increase to be more resulting from surface environmental management significantly more £60,000 and £120,000 will remain at resulting from surface policies, plans and strategies flooding and between than £120,000 and water flooding (£). than £150,000 and respectively. approximately £4,300 water flooding to be for the catchment must be £60,000 and more than £150,000 complied with, such as more than £200,000 and less than £60,000. minimal. £120,000 for respectively. *Estimation based on historical accommodating new housing respectively. damages observed in the within the catchment as estimated surface Brighton area from the 2000/ detailed by the South East water damages in the 2001 flood event (Binnie Black Plan and compliance with the future. & Veatch 2001 – Flood Habitats Directive. Defence Assessment of - Steep catchments of the Downland Flooding). South Downs result in rapid run-off and quick responses to rainfall events.

Environment Agency River Adur CFMP - Appendix B (September 2008) 79

Ensure that river Targets Opportunities The current annual The level of channel The level of channel channel and flood Maintain a suitable - Improvements in the channel and flood and flood defence efficiency of channel and and flood defence defence maintenance balance of annual river defence maintenance No channel and flood maintenance flood defence maintenance Channel and flood maintenance expenditure is channel and flood processes. expenditure is defence maintenance expenditure will Channel and flood defence maintenance expenditure will appropriate to the defence maintenance - Effective and efficient use of approximately expenditure is increase over time to developer contributions for defence maintenance expenditure remains at increase to be property economic expenditure (£) to £50,000; the annual incurred as no mitigate the affects of flood risk management. expenditure reduces to approximately £50,000. significantly more damage in urban areas annual average Constraints average damages maintenance is climate change to be less than £50,000. Annual average than £50,000. from flooding. damages from fluvial - Available funding for the from fluvial flooding to undertaken. Annual slightly more than Annual average damages from fluvial Annual average flooding to property (£). initial set up of new flood risk property are currently average damages £50,000. Annual management schemes. damages from fluvial flooding to property damages from fluvial around £4,000, and from fluvial flooding average damages from Not applicable. - Older flood defence flooding to property are increase over time due flooding to property Indicators structures are likely to be are likely to increase to property increase fluvial flooding to likely to be more than to the affects of climate are estimated to be Balance of annual river more costly to maintain. to more than £80,000 to be more than property will remain - Limited available information £120,000. The change to be more than less than £1,000. The channel and flood in the future. £150,000. The around £4,000. With on surface water and balance of expenditure £80,000. The balance balance of defence maintenance groundwater flood damages. balance of better maintenance to damages is of expenditure to expenditure to expenditure (£) to The current balance expenditure to efficiency and effective unacceptable. damages will become damages will be annual average of expenditure to damages is use of funding the unacceptable over time. unacceptable with damages from fluvial damages is unacceptable. balance of expenditure expenditure being flooding to property (£). considered to damages will remain unjustifiably high. acceptable. acceptable. Social objectives Opportunities No maintenance of Reduction in Targets - Provide development control channels and advice to ensure no increase maintenance of No significant increase drainage networks in run-off from the new Approximately 30 channels and drainage Improved channel in the number of people development proposed in the would result in an people and 13 networks would result maintenance, drainage Improved channel or properties affected by South East Plan (e.g. increase in the Burgess Hill). properties are at risk in an increase in the Maintenance of networks and localised maintenance, the 1% annual frequency, extent and - Reduce flood risk and of localised fluvial frequency, extent and channels and drainage protection measures increased local probability fluvial flood improve water quality by depth of localised flooding by the current depth of localised networks continues at will mitigate the affects defence works and event or surface water promoting and encourage fluvial and surface 1% annual probability fluvial and surface the current level. of climate change. The upgrading of the flooding in Burgess Hill the use of SuDS in the water and urban proposed urban flood event. This water and urban number of people and drainage network and and Hassocks in the drainage flooding. developments in Burgess increases to around drainage flooding. The number of people properties affected by warning service will future. Hill. 597 and 250 in the and properties at risk of localised fluvial reduce the number of - Continued practice and The number of development of the future. It is likely that the localised fluvial flooding flooding will remain at people affected by Indicators people and Ensure the impact of Emergency Response Plan number of people and is likely to increase to approximately 30 and localised fluvial Number of people and properties at risk of flooding on people and in Burgess Hill. An estimated 30 properties at risk of approximately 597 and 13 respectively. flooding to less than properties affected by Constraints localise fluvial property does not properties are at risk localise fluvial flooding 250 respectively. 5 and number of the 1% annual - Government and flooding will increase Not applicable. significantly increase in international legislation, of surface water and will increase to be The estimated number properties affected to probability fluvial flood to be more than 750 Burgess Hill and environmental management urban drainage more than 625 and 262 The estimated number of properties at risk of less than 2. event. policies, plans and strategies and 325 respectively. Hassocks in the future. flooding. This is likely respectively. of properties at risk of surface water and for the catchment must be complied with, such as to increase to surface water and urban urban drainage No properties will be The estimated* number The estimated accommodating new housing between 30 and 60 The estimated number drainage flooding is flooding will remain at at risk of surface of properties affected by within the catchment as number of properties properties in the of properties at risk of likely to increase to around 30. water and urban surface water flooding. detailed by the South East at risk of surface future. surface water and between 30 and 60. drainage flooding. Plan and compliance with the water and urban Habitats Directive. urban drainage Coverage of Flood *Surface water/ urban drainage flooding is Approximately 9 flooding is likely to The current level of Warning Service is Flood Warning drainage flooding likely to increase to properties are increase to more than Flood Warning Service increased, system is Service is improved estimates based on more than 100. currently covered by 75. remains in place. improved in terms of in terms of accuracy historical records. the Flood Warning accuracy and and coverage. Withdrawing the flood Service. The current level of coverage. Coverage of Flood warning system may Flood Warning Service Warning Service result in increased remains in place. risk to human life. Targets Opportunities Currently No maintenance of Reduction in Maintenance of Improved channel Improved channel - Provide development control No increase in flooding advice to ensure no increase approximately 0.04km channels and maintenance of channels and drainage maintenance, drainage maintenance, of A roads and railway in run-off from the new of A road, no extent of drainage networks channels and drainage networks continues at networks and localised increased local line or increase in extent development proposed in the railway and no critical would result in an networks would result the current level. protection measures defence works and Ensure the disruption of critical infrastructure South East Plan (e.g. infrastructure sites are increase in the in an increase in the There may be a slight will mitigate the affects upgrading of the caused by flooding to Burgess Hill). flooded, in Burgess Hill affected by the 1% frequency, extent and frequency, extent and increase in extent of A of climate change. drainage network will transport and critical - Potential for improving the and Hassocks, from a annual probability depth of localised depth of localised roads (slightly more then reduce fluvial and infrastructure does not current defences, for Not applicable. 1% annual probability example possible installation flood event. This is fluvial and surface fluvial and surface 0.04km) and railway or Approximately 0.04km surface water and increase in Burgess Hill fluvial flood event or of demountable or temporary not expected to water and urban water and urban critical infrastructure of A road and no extent urban drainage and Hassocks in the defences in Shoreham and surface water flooding. increase significantly drainage flooding. drainage flooding. sites affected by of railway or critical flooding. future. Burgess Hill. Constraints in the future. flooding during the 1% infrastructure sites are Indicators - Steep catchments of the More than 0.5km of A More than 0.1km of A annual probability flood affected by flooding No extent of A road, South Downs result in rapid Length of A road and run-off and quick responses There are no records road and some road and some lengths event. during the 1% annual railway or critical railway line (km) to rainfall events. of A roads, railway lengths of railway of railway and critical probability flood event. infrastructure sites

Environment Agency River Adur CFMP - Appendix B (September 2008) 80 affected by the 1% - Transport links in the and critical and critical infrastructure are likely There is likely to be a will be affected by catchment are a vital part of annual probability fluvial the communication network infrastructure site infrastructure sites to be at risk of flooding gradual increase from There will be no fluvial or surface flood event. regionally, nationally and being affected by are likely to be at risk from fluvial flooding the current extent of A change from the water and urban internationally, in particular surface water or of flooding from during the 1% annual roads, railway and current extent of drainage flooding. Number of critical the railways connecting urban drainage fluvial flooding during probability flood event. critical infrastructure at surface water and London to the south coast infrastructure sites and connecting the coastal flooding, however, the 1% annual risk of surface water and urban drainage affected by the 1% towns and cities, the A23, surface water and probability flood More surface water urban drainage flooding flooding to A roads, annual probability fluvial A24, A27, A259, A283 and urban drainage event. and urban drainage due to the affects of railways and critical flood event. A2032. flooding is a known flooding of A roads, climate change. infrastructure sites. problem in this area Significantly more railway and critical Number and period of and it is likely to surface water and infrastructure sites will recorded A road and increase in the future. urban drainage occur. railway closures due to flooding of A roads, surface water flooding*. railway and critical infrastructure sites Number of critical will occur. infrastructure sites recorded as being affected by surface water flooding*.

*Surface water/ urban drainage flooding estimates based on historical records. Environmental objectives There are no There are no There are no There are no There are no There are no There are no There are no There are no There are no environmental environmental environmental environmental environmental environmental environmental environmental environmental environmental objectives applicable to objectives applicable to objectives applicable to objectives applicable objectives applicable objectives applicable to objectives applicable to objectives applicable to objectives applicable objectives applicable this policy unit. this policy unit. this policy unit. to this policy unit. to this policy unit. this policy unit. this policy unit. this policy unit. to this policy unit. to this policy unit. Impact uncertain - Impact uncertain - Risk downstream Risk downstream Reduction in Reduction in Risk downstream will may increase due to may increase due Does this policy change flood risk locally or elsewhere: conveyance may conveyance may increase due to NA improved to improved benefit benefit downstream climate change conveyance conveyance downstream areas areas

Environment Agency River Adur CFMP - Appendix B (September 2008) 81 Form B7 – Summary of losses and gains.

Form B7 – Summary of losses and gains.

Policy unit Policy Unit 2 - Burgess Hill name/number:

Preferred policy Policy options Losses Gains option relative to current baseline Policy option P1 Environmental NO LOSSES NO GAINS Not preferred option – There are no gains

under this policy option. Social HIGH- NO GAINS The numbers of people and properties The number of people adversely affected by and properties at risk of removing FRM are localised fluvial flooding unacceptably high. This in a 1% AEP flood event option is therefore not will increase by more feasible. than 750 and 312 respectively The number of

properties at risk of surface water and urban drainage flooding will

increase by more than 70 Withdrawing the flood

warning system will increase risk to human life

The length of A road at risk from a 1% AEP flood event will increase

by more than 0.46km The length of railways and the number of

critical infrastructure at risk from a 1% AEP flood event will increase

Significantly more surface water and urban drainage flooding to

critical infrastructure and transport routes will occur

Economic HIGH- NO GAINS The AAD and economic damages caused by flooding will increase by more than £146,000 and £140,000 respectively The balance of FRM expenditure to AAD is unacceptable with AAD

Environment Agency River Adur CFMP - Appendix B (September 2008) 82 to property increasing by more than £146,000 Policy option P2 Environmental NO LOSSES NO GAINS Not preferred option – There are no gains

properties at risk of surface water and urban drainage flooding will

increase by more than 45 The length of A road at

risk from a 1% AEP flood event will increase by more than 0.06km

The length of railways and the number of critical infrastructure at

risk from a 1% AEP flood event will increase Significantly more

surface water and urban drainage flooding to critical infrastructure and

transport routes will occur

Economic HIGH- NO GAINS

The AAD and economic damages caused by flooding will increase by more than £121,000and £90,000 respectively The balance of FRM expenditure to AAD is unacceptable with AAD to property increasing by more than £121,000 Policy option P3 Environmental NO LOSSES NO GAINS Not preferred option – There are no gains

under this policy option. Social MEDIUM- NO GAINS The numbers of people and properties The number of people adversely affected by and properties at risk of removing FRM will localised fluvial flooding become unacceptably in a 1% AEP flood event high in the future. This will increase by option is therefore not Environment Agency River Adur CFMP - Appendix B (September 2008) 83 approximately 567 and feasible. 237 respectively

The number of properties at risk of surface water and urban

drainage flooding will increase by up to 30 The length of A road at

risk from a 1% AEP flood event will increase slightly

The length of railways and the number of critical infrastructure at

risk from a 1% AEP flood event will increase slightly

More surface water and urban drainage flooding to critical infrastructure

and transport routes will occur in the future

MEDIUM- Economic NO GAINS The AAD and economic

damages caused by flooding will increase by approximately £76,000 and up to £60,000 respectively The balance of FRM expenditure to AAD will become unacceptable with AAD to property increasing by more than £76,000 in the future Policy option P4 Environmental NO LOSSES NO GAINS Preferred Policy Option – There are no losses

under this policy. The Social NO LOSSES HIGH+ numbers of people and properties affected by The number of people flooding and the and properties at risk disruption caused will of localised fluvial not increase in the flooding in a 1% AEP future. The AAD and flood event will not economic damages will increase in the future remain constant and the The number of associated future FRM properties at risk of expenditure will be surface water and efficient. urban drainage flooding will not

increase in the future The length of A road at risk from a 1% AEP

flood event will not increase in the future The length of railways

Environment Agency River Adur CFMP - Appendix B (September 2008) 84 and the number of critical infrastructure at

risk from a 1% AEP flood event will not increase in the future

Surface water and urban drainage flooding to critical

infrastructure and transport routes will not occur in the future

Economic NO LOSSES HIGH+

The AAD and economic damages caused by flooding will not increase in the future The balance of FRM expenditure to AAD will remain acceptable with slight increases in FRM expenditure to maintain AAD to property at current levels in the future Policy option P5 Environmental NO LOSSES NO GAINS Not preferred option – Although there are

additional gains in terms Social NO LOSSES HIGH+ of reducing the numbers of people and properties The number of people affected by flooding and and properties at risk minimising the of localised fluvial disruption it causes, flooding in a 1% AEP these benefits are flood event will be marginal in relation to reduced by more than additional FRM 25 and more than 11 expenditure. This option respectively is therefore not efficient. The number of properties at risk of surface water and

urban drainage flooding will be reduced from

approximately 30 to 0 The length of A road at risk from a 1% AEP

flood event will be reduced The length of railways

and the number of critical infrastructure at risk from a 1% AEP

flood event will be reduced Surface water and

urban drainage

Environment Agency River Adur CFMP - Appendix B (September 2008) 85 flooding to critical infrastructure and

transport routes will not occur in the future

Economic MEDIUM- HIGH+ The balance of FRM expenditure to AAD will The AAD and become unacceptable in economic damages the future with significant caused by flooding will increases in FRM be reduced expenditure to reduce AAD to property by more than £3,000 Policy option P6 Environmental Not applicable Not applicable Not preferred option – this Policy Option is not

considered feasible in Social this policy unit.

Economic

Key HIGH: High negative A policy has a ‘high negative’ effect where it could contribute to a social, economic or environmental objective in a significantly negative way. A ‘high negative’ effect could be: (i) a very large increase in current flood risk; (ii) very large projected increases in flood risk under future conditions, and/or; (iii) significant additional social, economic and/or environmental losses. MEDIUM: Medium negative A policy has a ‘medium negative’ effect where it could contribute to a social, economic or environmental objective in a negative way. A ‘medium negative’ effect could be: (i) an increase in current flood risk; (ii) a projected increase in flood risk under future conditions, and/or; (iii) social, economic and/or environmental losses. LOW: Low negative A policy has a ‘low negative’ effect where it could make a limited contribution to a social, economic or environment objective, but where the overall contribution would be negative. A ‘low negative’ effect could be: (i) an overall increase in current flood risk; (ii) an overall increase in flood risk under future conditions, and/or; (iii) overall social, economic and/or environmental losses. NEUTRAL: Neutral A policy has a ‘neutral’ effect where it makes neither a positive or negative contribution to a social, economic or environmental objective. A ‘neutral’ effect could be: (i) no change in current level of risk. In this instance the current level of risk would have to be low, so that the residual risk after a neutral policy was implemented remained acceptable; (ii) no change in flood risk under future conditions. In this instance projected future risk would need to be low so that the residual risk after a neutral policy was implemented remained acceptable, and/or; (iii) no additional social, economic and/or environmental gains or losses. Policy options may also be ‘neutral’ where they are not relevant in a particular Environment Agency River Adur CFMP - Appendix B (September 2008) 86 policy unit, or where it is not feasible for a policy option to contribute to an objective. HIGH: High positive A policy has a ‘high positive’ effect where it could contribute to a social, economic or environmental objective in a significantly positive way. A ‘high positive’ effect could be: (i) a very large reduction in current flood risk; (ii) avoiding/reducing very large projected increases in flood risk under future conditions, and/or; (iii) significant additional social, economic and/or environmental gains. MEDIUM: Medium positive A policy has a ‘medium positive’ effect where it could contribute to a social, economic or environmental objective in a positive way. A ‘medium positive’ effect could be: (i) a reduction in current flood risk; (ii) avoiding/reducing projected increases in flood risk under future conditions, and/or; (iii) additional social, economic and/or environmental gains. LOW: Low positive A policy has a ‘low positive’ effect where it could make a limited contribution to a social, economic or environment objective, but where the overall contribution would be positive. A ‘low positive’ effect could be: (i) an overall reduction in current flood risk; (ii) an overall avoidance/reduction in flood risk under future conditions,

Environment Agency River Adur CFMP - Appendix B (September 2008) 87

Form B8 Summary of preferred policy Policy unit 2 – Burgess Hill Physical characteristics: - Largely comprising the urban areas Burgess Hill and Hassocks. - Policy unit is split between the High and Low Weald Landscape Character Areas. - The extreme north and extreme south of the unit area overlie sandstone (Cuckfield Member), and Weald Clays predominate throughout the central section. - The source of the Adur East Branch emerges amongst undulating topography east of Burgess Hill. - Ditchling Common SSSI grassland habitat requires a wide variation in drainage conditions. - Flood risk in Burgess Hill may increase due to pressure for urban expansion and development. Flood mechanism: - Relatively rapid runoff from steep slopes in the High Weald. - A combination of surface water flooding, urban drainage problems and under capacity of local streams causing localised areas of fluvial flooding and urban flooding. Receptor: Problem/risk - People, properties and infrastructure in Burgess Hill and Hassocks. - Local minor roads. - Currently approximately 13 properties at risk of fluvial flooding in the policy unit from the 1% annual probability fluvial flood event, which is expected to increase to 250 due to climate change. Current Flood Risk Summary Number of properties at risk of flooding (1% annual probability flood event) 13 Total damages (approx.) (1% annual probability flood event) £0.110 million Annual averages damages (approx.) £4,000 Future Flood risk: - Flood risk from fluvial flooding is currently assessed as low, assessment increases to medium in the future. - Flood risk from surface water flooding and urban drainage problems is currently assessed as low to medium, assessment becomes medium in the future. Future Flood Risk Summary (in 100 years time) Number of properties at risk of flooding (1% annual probability flood event) 250 Total damages (approx.) (1% annual probability flood event) £2 million Annual averages damages (approx.) £77,000 Policy 4 - Take further action to sustain current scale of flood risk into the future (responding Policy selected to the potential increases in flood risk from urban development, land use change, and climate change). Policy 4 sets a framework which prevents the level of flood risk increasing in the future as a result of climate change or increased urban growth. It does not, however, support extensive effort in reducing flood risk from its current level either now or in the future. Current maintenance activities include grass and weed cutting, debris removal cutting back overhanging branches. This may have to increase in the future under a policy 4 option. This policy is appropriate for this policy unit for the following reasons: Justification - The current level of flood risk is low. - Climate change and urban development could increase future levels of flood risk from localised flooding. - This policy would achieve the economic and social objectives of making sure that flood risk does not increase in the future as a result of climate change and/or urban development. - Ensure flood damages do not increase in Burgess Hill and Hassocks due to future change (urban development and climate change). - Ensure that river channel and flood defence maintenance expenditure is appropriate to Catchment the property economic damage in urban areas from flooding. objectives - Ensure the impact of flooding on people and property does not significantly increase in Burgess Hill and Hassocks in the future. - Ensure the disruption caused by flooding to transport and critical infrastructure does not increase in Burgess Hill and Hassocks in the future. Opportunities: Catchment-wide - Provide development control advice to ensure no increase in run-off from the new opportunities development proposed in the South East Plan (e.g. Burgess Hill). and constraints - Reduce flood risk and improve water quality by promoting and encourage the use of Environment Agency River Adur CFMP - Appendix B (September 2008) 88 SuDS in the proposed urban developments in Burgess Hill. - Potential for improving the current defences, for example possible installation of demountable or temporary defences in Shoreham and Burgess Hill. - Continued practice and development of the Emergency Response Plan in Brighton and Hove, Worthing, Shoreham, and Burgess Hill. - Improvements in the efficiency of channel and flood defence maintenance processes. - Effective and efficient use of developer contributions for flood risk management.

Constraints: - Government and international legislation, environmental management policies, plans and strategies for the catchment must be complied with, such as accommodating new housing within the catchment as detailed by the South East Plan and compliance with the Habitats Directive. - Steep catchments of the South Downs result in rapid run-off and quick responses to rainfall events. - Available funding for the initial set up of new flood risk management schemes. - Older flood defence structures are likely to be more costly to maintain. - Limited available information on surface water and groundwater flood damages. - Transport links in the catchment are a vital part of the communication network regionally, nationally and internationally, in particular the railways connecting London to the south coast and connecting the coastal towns and cities, the A23, A24, A27, A259, A283 and A2032. Policy 1 - do nothing. The urban areas of Burgess Hill and Hassocks currently have a low risk of flooding. However, the risk of flooding from surface water and rivers may increase with climate change and urban development. Without continued maintenance the damages and losses would increase. The number of people at risk from river flooding would increase to more than 750. Do nothing is, therefore, not an appropriate policy.

Policy 2 - reduce current level of flood risk management. As with policy option 1, the potential damages and losses would become unacceptable in the future under a ‘do less’ policy. The number of people at risk from river flooding would increase to more than 625. Alternative

policies Policy 3 - maintain the current level of flood risk management. Although the current level of considered flood risk is considered acceptable, it has been shown that flood risk will increase in the future due to a combination of fluvial, surface water and urban drainage flooding. This policy is therefore not acceptable.

Policy 5 - reduce the level of flood risk, both now and in the future. The current level of risk is considered tolerable and therefore this policy is not justified.

Policy 6 - increase flooding to reduce flooding elsewhere. There are no opportunities within this policy unit for this policy. We have estimated the future increase in flood risk within this policy unit on the best available prediction we have of climate change, frequency and size of storms and flood events in the future. Due to limitations in the modelling the properties at risk in the future have been Uncertainties adjusted based on Flood Zones and as such the future AAD has been estimated. and

dependencies Delivering this policy will partly depend on developing and implementing an effective urban drainage strategy in partnership with the local drainage authority, highway department, water and sewerage company and other relevant authorities or responsible parties.

Environment Agency River Adur CFMP - Appendix B (September 2008) 89 Form B9 Requirements for further policy development and appraisal Policy unit 2 – Burgess Hill Is there a need for further policy development? No If yes, then mark policy options for more detailed development. Some complex policies may require more detailed development, probably at Strategy Plan level. Is there a need for further more detailed appraisal? No If yes, take forward to strategy study.

Environment Agency River Adur CFMP - Appendix B (September 2008) 90

Form B10 Indicators for monitoring, review and evaluation This form sets out the indicators that need to be included in the policy implementation plan, for policy monitoring, drawing on the residual risks and likely impacts identified above. This will allow better review and evaluation of the policy when implemented. Policy unit 2 – Burgess Hill Indicators to be included in policy unit 2 implementation plan are:

Economic - Total annual average damages (to properties and agriculture) from fluvial flooding (£AAD). - Estimated damages resulting from surface water flooding (£) (based on historical damages). - Balance of annual river channel and flood defence maintenance expenditure (£) to annual average damages from fluvial flooding to property (£).

Social - Number of people and properties affected by the 1% annual probability fluvial flood event. - The estimated number of properties affected by surface water flooding (based on historical records). - Length of A road and railway line (km) affected by the 1% annual probability flood event. - Number and period of recorded A road and railway closures due to surface water flooding (based on historical records). - Number of critical infrastructure sites affected by the 1% annual probability flood event. - Number of critical infrastructure sites recorded as being affected by surface water flooding (based on historical records).

Environment Agency River Adur CFMP - Appendix B (September 2008) 91

Policy unit 3 Steyning and Upper Beeding Policy appraisal forms Form B5 – Summary of current and future levels of and responses to flood risk. Form B6 – Appraisal of policy options against policy unit objectives. Form B7 – Summary of losses and gains. Form B8 – Summary of preferred policy. Form B9 – Requirements for further policy development and appraisal. Form B10 – Indicators for monitoring, review and evaluation.

Environment Agency River Adur CFMP - Appendix B (September 2008) 92

Form B5 Summary of current and future levels or and responses to flood risk Policy unit 3 – Steyning and Upper Beeding Defences: There is a total of 3.5km of culverted channel sections and flood embankments to both banks along the River Adur throughout this policy unit.

Flood warning: This area is included in the Lower Adur flood warning area. There are more than 110 properties connected to the flood warnings direct Current responses to flood risk service. within the policy unit

Maintenance: We currently carry out annual inspection and maintenance of the tidal embankments and land drainage sluice gates. The estimated annual cost of maintaining the channels and existing defences under the Environment Agency’s responsibility is approximately £60,000. Standard of protection: The River Adur embankments are considered to offer Standards of service that apply protection ranging from the 3.3% annual probability fluvial flood event (1 in 30) to to flood defences within the the 2% annual probability fluvial flood event (1 in 50). They are considered to be policy unit at or above the target condition. In 10% flood In 1% flood In 0.1% flood Receptors outline* outline* outline* Residential properties 3 91 103 Commercial properties 0 11 N/A Population 0 210 N/A Property damages 0 £2.944 million N/A Agricultural damages £2,355 £7,140 N/A A roads 0 km 0.76 km 0.48 km Railways 0 km 0 km 0 km Agricultural land Grade 1 0 km2 0 km2 0 km2 Agricultural land Grade 2 0 km2 0 km2 0 km2 What is currently exposed to Agricultural land Grade 3 0.05 km2 0.11 km2 0.15 km2 flooding? Agricultural land Grade 4 0.23 km2 0.89 km2 1.06 km2 Agricultural land Grade 5 0 km2 0 km2 0 km2 SNCIs 0.23 km2 0.53 km2 0.65 km2 SSSI 0 km2 0 km2 0 km2 Listed Buildings 0 3 4 SM 3 9 10 AONB 0 km2 0.24 km2 0.27 km2 ESA 0 km2 0.26 km2 0.29 km2 Registered Historic Parks and 2 2 2 Gardens 0 km 0 km 0 km Proposed National Park 0.28 km2 0.84 km2 0.96 km2 * 10% and 1% based on broadscale model results and 0.1% based on Flood Zone 2 Economic and social receptors: There is flood risk to people, properties and infrastructure in Steyning, Upper Beeding and Bramber from fluvial flooding, surface water flooding and some urban drainage flooding.

Currently 102 properties are at risk of fluvial flooding in the policy unit from the 1% annual probability fluvial flood event. The majority of these properties are residential.

Short sections of the A283 and A2037 lie in the 1% annual probability flood event Who and what are currently outline. most vulnerable to flood

damage and losses? Only moderate to low grade agricultural land (Grades 3 and 4) is at risk of localised fluvial flooding.

Environmental designations: There are no internationally designated sites or SSSIs at risk of flooding within this policy unit.

Total area of approximately 0.5km2 of the River Adur Water Meadows and Wyckham Wood SNCI is located within the 1% annual probability flood event outline in this policy unit. The sensitivity of this site to flooding is low and may

Environment Agency River Adur CFMP - Appendix B (September 2008) 93 benefit from periodic flooding.

Landscape: Approximately 0.25km of the Sussex Downs AONB and South Downs ESA and 0.84km2 of the proposed South Downs National Park is located within the 1% annual probability flood outline in this policy unit.

Natural and Historic Environment: Three listed buildings are within the1% annual probability flood event outline, increasing slightly to four within the extreme flood outline.

There are no registered historic parks and gardens within this policy unit.

There are nine SMs (salterns) within the 1% annual probability flood event outline. This increases to ten SMs (salterns) within the 0.1% annual probability flood event outline. Increase in frequency of storm events resulting more frequent fluvial and surface water flooding. Sea level rise* increases the likelihood of tidally influenced flooding in this policy unit. What are the key factors that *To represent future sea level rise, the tidal boundary within the broadscale model was scaled to increase the maximum still water level by 600mm for the 100 year timescale. These climate change could drive future flood risk? figures used were the accepted approach for ‘typical’ catchments when the scoping stage broadscale modelling was carried out. Since the scoping stage was completed new Defra guidance (October 2006) on climate change has been released which suggest that for a 100 year time scale, sea level may rise by almost 1m. Therefore the results from the broadscale model in the tidally influenced areas are likely to have under predicted the increase in flood risk and damages in the future. There is an increase (approximately £0.1 million) in AAD due to climate change What are the possible future over the next 100 years. levels of flood risk under the main scenarios? In 100 years just over 110 properties are at risk of flooding in the policy unit from the 1% annual probability fluvial flood event. Improve existing or construct new defences and reduction in flows entering the What potential responses (or catchment through improved management or attenuation upstream. This policy groups of responses) are unit is unsuitable for large scale attenuation; small scale attenuation is unlikely to being considered to manage successfully manage flood risk alone. An improvement in land use run-off flood risk? management in upstream catchments could reduce flows entering this policy unit. We have estimated the future increase in flood risk within this policy unit on the best available prediction we have of climate change, frequency and size of What gaps and uncertainties storms and flood events in the future. are there in knowledge, and what assumptions have been Delivering this policy will partly depend on developing and implementing effective made? urban drainage in partnership with the local drainage authority, highway department, water and sewerage company and other relevant authorities or responsible parties.

Environment Agency River Adur CFMP - Appendix B (September 2008) 94 Generic response: Rural land use change – changing farming practices to reduce run-off rates 1% annual probability fluvial flood Results from broadscale modelling damages (£m) The broadscale modelling has indicated that a change in the way land is Future basecase = £3.711 managed, in the upper parts of the CFMP area, has a positive impact on flood damages within this policy unit. Flood damages are shown to decrease by 6% Generic response = £3.504 for the 1% annual probability fluvial flood event. % change = -6% Conclusions The reduction in damages for the 1% annual probability fluvial flood event is small.

Although the impact on flood risk from changing land use in the upper catchment is not large, it is nonetheless significant and together with other flood risk management options, land use change in the upper catchment can provide a useful way of reducing flood risk to Steyning and Upper Beeding.

Generic response: Reducing the height of all raised embankments along the River Adur 1% annual probability fluvial flood Results from broadscale modelling damages (£m) Removing the embankments along the River Adur allows more frequent inundation of the floodplain on both sides of the river. The results from the Future basecase = £3.711 broadscale modelling show a large reduction of 58% for a 1% annual Generic response = £2.342 probability fluvial flood event. At Steyning and Upper Beeding, water depths are reduced from between 0.5 to 0.8m. % change = -58% Conclusions The impact of lowering the embankments along the River Adur within this policy unit is surprising as the larger, more extreme fluvial flood events result in a reduction of flood damages in Steyning and Upper Beeding. This is because the increased inundation of the floodplains upstream and downstream of Steyning and Upper Beeding has the effect of reducing the peak water levels in the River Adur and allows water to drain away more effectively from the floodplains, lowering the water depths through the urban areas.

The impact is complex however, and reducing the height of the raised embankments does not result in reductions in flood depths everywhere. Some locations that would normally be defended to some extent by the existing defences will receive greater depths of flooding for an equivalent size of flood event.

For the more frequent, less severe events the flood damages increase. This has the effect of increasing the annual average damages, which take into account a wide range of flood severity in the calculation.

Generic response: Increasing conveyance on the Adur East Branch 1% annual probability fluvial flood Results from broadscale modelling damages (£m)

The broadscale modelling has indicated that increasing conveyance in the Future basecase = £3.711 whole of the Adur East Branch has minimal impact at Steyning and Upper Generic response = £3.722 Beeding. % change = +0.3% Conclusions The benefits experienced from the increased conveyance on the Adur East Branch are evident (see policy unit 2). However, the flood mechanisms at Steyning and Upper Beeding are dominated by tidal influences and the impact of any changes in fluvial flows upstream are small in comparison.

Generic response: Attenuation/retention (storage) on the Adur West Branch 1% annual probability fluvial flood Results from broadscale modelling damages (£m) The broadscale modelling has indicated that applying flood storage on the Adur West Branch (of no specific size or location) has a small positive effect Future basecase = £3.711 on flood damages within this policy unit (approximately £0.231 million Generic response = £3.480 decrease in flood damages). The results show a 6% decrease in flood damages for the 1% annual probability fluvial flood event. % change = -6% Conclusions A large flood storage reservoir on the Adur West Branch will provide some benefit to Steyning and Upper Beeding by reducing flood damages. The effect on flood extent in this policy unit is minimal, however there is a reduction of approximately 0.1 to 0.15 m in flood depth, which results in the decrease in flood damages. Environment Agency River Adur CFMP - Appendix B (September 2008) 95

Generic response: Barrier across the River Adur at Shoreham Harbour 1% annual probability fluvial flood Results from broadscale modelling damages (£m) This case looks at the situation where a barrier is built across the mouth of the river that keeps the tide out, but allows free discharge of the river into the sea Future basecase = £3.711 at low tide. The modelling has shown that the reduction in flooding through this approach is not significant for the 1% annual probability fluvial flood event Generic response = £3.611 within this policy unit. The annual average damage value, however, does % change = -1% show a significant reduction in flood damages, of approximately 30%. Conclusions Although this approach has shown not to be effective at reducing flood damages for the 1% annual probability fluvial flood event, it has however, shown a significant reduction in flood damages for the more frequent events. For the 4% annual probability fluvial flood event there is a reduction of approximately 56% on flood damages and for the 10% event the reduction is 94%.

This flood management response allows free flow of water out of the river, but prevents water from the sea entering at high tide. High tides will still have an effect on flooding within the river by preventing discharge when the water level in the sea is higher than the water levels in the river. However, it is the duration of this tide locked condition that is important and not the actual sea level reached by the high tide.

Cost and technical feasibility is not a prime consideration for the CFMP, however it must be recognised that this approach would need further investigation.

Environment Agency River Adur CFMP - Appendix B (September 2008) 96 Form B6 Appraisal of policy options against policy unit objectives Policy unit 3 – Steyning and Upper Beeding KEY = Scale of policy impact on objective: Not appraised Baseline Meets objective No impact Doesn’t meet object Uncertain The preferred policy option is indicated below by the policy option highlighted in pink Baseline (current Policy 1 Policy 2 Policy 3 Policy 4 Policy 5 Policy 6 and future) No maintenance of watercourses. Channels become blocked with vegetation and Reduction in conveyance is maintenance of Improved level of reduced. watercourses. Improved level of channel maintenance Maintenance of the Channels become channel maintenance of watercourses. Current and future The height of raised channels continues. blocked with vegetation of watercourses. Not considered baseline with current embankments would and conveyance is The flood warning feasible in this policy flood risk reduce over time. The flood warning Localised protection reduced. service is improved. unit. management. service remains in measures introduced.

The flood warning place. The flood warning The flood warning Increase the local service is withdrawn. service is improved. service remains in defence works.

place. A do nothing approach would increase the flooding Catchment Targets and Opportunities and in an unmanaged and objectives Indicators Constraints unpredictable way. Economic objectives Opportunities - Provide development control advice to ensure no increase Targets in run-off from new No significant increase development. in damages in Steyning - Reduce flood risk and improve water quality by The current total No maintenance of and Upper Beeding from promoting and encourage the fluvial, surface water and use of SuDS in proposed annual average channels and a As channels decrease The total annual developments. damages from fluvial reduction in the in conveyance and average damages urban drainage flooding Improved channel - Investigate removal of flooding are height of the capacity due to from fluvial flooding due to future changes maintenance and Improved channel Environment Agency owned approximately embankments would reduced maintenance will increase over time (urban development and and maintained existing localised protection maintenance and £86,000; this lead to a significant the total annual due to the affects of climate change). raised defences to reinstate measures will mitigate increased local the floodplain between increases to around increase in flooding average damages from climate change to be Ensure flood damages the affects of climate defence works would Partridge Green and £206,000 in the future. with total annual fluvial flooding will approximately do not significantly Indicators Steyning and between change. The total reduce total annual average damages increase to be more £206,000. increase in Steyning and Total annual average Steyning and Shoreham to a annual average average damages naturally functioning state, to There are no historic from fluvial flooding than £330,000. Upper Beeding due to damages (to properties damages from fluvial from fluvial flooding Not applicable. provide flood storage and records of surface increasing to more There are no records future change (urban and agriculture) from flooding will remain at to be less than enhance conservation value water flooding and than £500,000. There will be a of surface water development and fluvial flooding (£AAD). and biodiversity. approximately £86,000. £10,000 and therefore we have not substantial increase flooding, however, a climate change). Constraints damages resulting - Government and international been able to estimate No maintenance will from the current level slight increase in Estimated* damages Surface water flooding from surface water legislation, environmental the damages, lead to a significant of surface water surface water flooding resulting from surface management policies, plans and associated flooding to be however, surface increase from the flooding and and associated water flooding (£). and strategies for the damages will remain at minimal. catchment must be complied water flooding is a current level of associated damages damages is likely due the current levels. *Estimation based on historical with, such as accommodating known problem in this surface water with a reduction in to the affects of damages observed in the new housing within the catchment as detailed by the area and it is likely to flooding and maintenance. climate change. Brighton area from the 2000/ increase in the future. associated damages. 2001 flood event (Binnie Black South East Plan and & Veatch 2001 – Flood Defence compliance with the Habitats Assessment of Downland Directive. Flooding). - Steep catchments of the South Downs result in rapid run-off and quick responses to rainfall events.

Environment Agency River Adur CFMP - Appendix B (September 2008) 97 The level of channel and flood defence The level of channel Targets The current annual Channel and flood maintenance and flood defence Maintain a suitable channel and flood No channel and flood defence maintenance expenditure will maintenance balance of annual river Opportunities defence maintenance defence maintenance Channel and flood expenditure remains increase over time to expenditure will channel and flood - Improvements in the expenditure is expenditure is defence maintenance efficiency of channel and at approximately mitigate the affects of increase to be defence maintenance approximately incurred as no expenditure reduces to flood defence maintenance £60,000. Annual climate change to significantly more Ensure that river expenditure (£) to processes. £60,000; the annual maintenance is be less than £60,000. average damages slightly more than than £60,000. channel and flood annual average - Effective and efficient use of average damages undertaken. Annual Annual average developer contributions for from fluvial flooding to £60,000. Annual Annual average defence maintenance damages from fluvial from fluvial flooding to average damages damages from fluvial flood risk management. property increase over average damages from damages from fluvial expenditure is flooding to property (£). Constraints property are currently from fluvial flooding flooding to property are time due to the affects fluvial flooding to flooding to property Not applicable. appropriate to the - Available funding for the around £85,800, to property increase likely to be more than of climate change to property will remain are estimated to be property economic Indicators initial set up of new flood risk increasing to around to be more than £310,000. management schemes. be around £205,000. around £85,800. less than £10,000. damage in urban areas Balance of annual river £205,000 in the future. £450,000. - Older flood defence from flooding. channel and flood structures are likely to be The balance of The balance of With better The balance of defence maintenance more costly to maintain. The current balance of The balance of expenditure to - Limited available information expenditure to maintenance efficiency expenditure to expenditure (£) to expenditure to expenditure to damages is on surface water and damages is and effective use of damages will be annual average groundwater flood damages. damages is damages is unacceptable. considered to be funding the balance of unacceptable with damages from fluvial considered unacceptable. acceptable. expenditure to expenditure being flooding to property (£). acceptable. damages will remain unjustifiably high. acceptable. Social objectives Opportunities Approximately 215 No maintenance of - Provide development control advice to ensure no increase people and 102 channels and a in run-off from new properties are at risk reduction in the Reduction in development. of localised fluvial height of maintenance of Maintenance of Targets - Reduce flood risk and flooding by the current embankments would channels would result channels and Improved channel No significant increase improve water quality by 1% annual probability result in a significant in an increase in the drainage networks maintenance, drainage in the number of people promoting and encourage the use of SuDS in proposed flood event. This increase in the frequency, extent and continues at the networks and localised Improved channel or properties affected by developments. increases slightly to frequency, extent and depth of localised current level. protection measures maintenance and the 1% annual - Investigate removal of around 270 people depth of localised fluvial and surface and will mitigate the affects increased local probability fluvial flood Environment Agency owned and 115 properties in fluvial and surface urban drainage The number of people of climate change. The defence works and event or surface water and maintained existing raised defences to reinstate the future. water and urban flooding. and properties at risk number of people and flood warning service flooding in Steyning and the floodplain between drainage flooding. of localised fluvial properties affected by will reduce the Upper Beeding in the Partridge Green and There are no historic It is likely that the flooding is likely to localised fluvial number of people future. Steyning and between Steyning and Shoreham to a records of surface The number of number of people and slightly increase to flooding will remain at affected by localised

Ensure the impact of naturally functioning state, to water and urban people and properties properties at risk of approximately 270 approximately 215 and fluvial flooding to less Indicators flooding on people and provide flood storage and drainage flooding and at risk of localise localise fluvial flooding and 115 respectively. 102 respectively. than 25 and number Number of people and enhance conservation value property does not therefore we have not fluvial flooding will will increase to be of properties affected properties affected by and biodiversity. Not applicable. significantly increase in Constraints been able to estimate increase to be more more than 285 and 120 Over time the number The estimated number to less than 10. the 1% annual Steyning and Upper - Government and international the number of than 310 and 130 respectively. of properties at risk of of properties at risk of probability fluvial flood legislation, environmental Beeding in the future. properties affected by respectively. surface water and surface water and No properties will be event. management policies, plans these sources of There will be a urban drainage urban drainage at risk of surface and strategies for the catchment must be complied flooding. However, There will be a substantial increase flooding will gradually flooding will remain at water and urban The estimated* number with, such as accommodating surface water and significant increase from the current level in increase from the the current level. drainage flooding. of properties affected by new housing within the urban drainage from the current level the number of current level due to surface water flooding. catchment as detailed by the South East Plan and flooding is a known in the number of properties affected by the affects of climate Coverage of Flood Flood Warning

compliance with the Habitats problem in this area properties affected by surface water and change. Warning Service is Service is improved *Surface water/ urban drainage Directive. flooding estimates based on - Visual impact of flood risk and it is likely to surface water and urban drainage increased, system is in terms of accuracy historical records. management activities within increase in the future. urban drainage flooding. The current level of improved in terms of and coverage the proposed National Park flooding. Flood Warning accuracy and Coverage of Flood or Areas of Outstanding Approximately 89 The current level of Service remains in coverage. Warning Service Natural Beauty. properties are Withdrawing the flood Flood Warning Service place. currently covered by warning system may remains in place. the Flood Warning result in increased Service. risk to human life.

Environment Agency River Adur CFMP - Appendix B (September 2008) 98 Targets Opportunities - Provide development control No increase in flooding advice to ensure no increase of A roads and railway in run-off from new line or increase in extent development. There is no extent of of critical infrastructure - Investigate removal of Environment Agency owned railway within this No maintenance of flooded, in Steyning and and maintained existing policy unit. channels and Maintenance of Upper Beeding and raised defences to reinstate drainage networks channels and Reduction in surrounding areas, from the floodplain between Currently and a reduction in the drainage networks Partridge Green and maintenance of Improved channel a 1% annual probability approximately 0.76km height of continues at the Steyning and between channels would result maintenance, drainage fluvial flood event or Steyning and Shoreham to a of A road and no embankments would current level. in an increase in the networks and localised surface water flooding. naturally functioning state, to critical infrastructure result in an increase provide flood storage and frequency, extent and protection measures sites are affected by in the frequency, In the future only a Improved channel enhance conservation value depth of localised will mitigate the affects Indicators the 1% annual extent and depth of minor increase in maintenance and and biodiversity. fluvial and surface and of climate change. Length of A road and Constraints probability flood event. localised fluvial and length of A road is increased local urban drainage railway line (km) affected - Steep catchments of the surface and urban affected by the 1% defence works will South Downs result in rapid flooding. Approximately 0.76km by the 1% annual In the future only a drainage flooding. annual probability reduce fluvial and Ensure the disruption run-off and quick responses of A road and no probability fluvial flood to rainfall events. minor increase in flood event. surface water and caused by flooding to More than 1km of A critical infrastructure event. - Transport links in the length of A road is More than 1.2km of A urban drainage transport and critical road is likely to be at sites are affected by catchment are a vital part of affected by the 1% road is likely to be at There will be a minor flooding. infrastructure does not the communication network risk of flooding from flooding during the 1% Not applicable. Number of critical annual probability risk of flooding from increase, from the increase in Steyning and regionally, nationally and fluvial flooding during annual probability flood infrastructure sites internationally, in particular flood event. fluvial flooding during current risk, of surface No extent of A road Upper Beeding in the the 1% annual event. affected by the 1% the railways connecting the 1% annual water and urban or critical future. London to the south coast probability flood event. annual probability fluvial There are no records probability flood drainage flooding to A infrastructure sites and connecting the coastal There will be no flood event. towns and cities, the A23, of A road and critical event. roads and critical will be affected by More surface water change from the A24, A27, A259, A283 and infrastructure sites infrastructure sites. fluvial or surface A2032. and urban drainage current extent of Number and period of being affected by Substantially more water and urban - Visual impact of flood risk flooding of A roads. surface water and recorded A road and surface water and surface water and The minor increase in drainage flooding. management activities within Surface water and urban drainage railway closures due to the proposed National Park urban drainage urban drainage risk of flooding does urban drainage flooding to A roads and surface water flooding*. or Areas of Outstanding flooding, however, flooding of A roads. not lead to a notable Natural Beauty. flooding may affect critical infrastructure surface water and Surface water and increase in disruption, some critical sites. Number of critical urban drainage urban drainage therefore this policy infrastructure sites. infrastructure sites flooding is a known flooding may affect option does meet the recorded as being problem in this area some critical objective. affected by surface and it is likely to infrastructure sites. water flooding*. increase in the future.

*Surface water/ urban drainage flooding estimates based on historical records. Environmental objectives Opportunities Doing nothing and - Help meet national biodiversity action plan (BAP) reducing the height of embankments would Reducing the targets. Improved channel - Investigate removal of allow the rivers to maintenance of the Environment Agency owned There is currently maintenance and 2 flood more frequently channels would and maintained existing 0.53km of the SNCI increased local and increase the eventually allow the raised defences to reinstate located within the 1% This is a small defence works will the floodplain between flood depths, rivers to flood more annual probability increase to around reduce the extent of Targets Partridge Green and increasing the area of frequently and increase 2 The extent of the SNCI flood event outline. 0.63km in the area of flooding and Protect and enhance the Steyning and between the SNCI within the the flood depths, within the 1% annual Steyning and Shoreham to a the SNCI within the therefore the extent River Adur Water 1% annual probability increasing the area of probability flood event Protect and enhance the naturally functioning state, to This is a small 1% annual probability of the SNCI within the Meadows and Wyckham provide flood storage and flood outline to the SNCI within the 1% outline will remain at River Adur Water enhance conservation value increase to around flood event outline due 2 1% annual probability Wood Site of Nature 2 substantially more annual probability flood approximately 0.53km . Meadows and Wyckham and biodiversity. 0.63km of the SNCI 2 to the affects of flood outline to less Conservation than 0.63km . outline to more than 2 Not applicable. Wood Site of Nature Constraints located within the 1% 2 climate change in the than 0.53km . Importance. - Some environmentally 0.63km . There will be no Conservation annual probability future. There maybe designated habitats are There is increased notable change in the Importance. flood event outline in some potential to Decrease in flooding Indicators susceptible to changes in potential to There is increased habitat and species flood frequency, floodwater the future. There improve or increase extent (duration and Habitat quality and substantially improve potential to improve or diversity within the chemistry, groundwater maybe some potential the habitat types and depth) will reduce the species diversity. levels and drainage system or increase the increase the habitat SNCI. to improve or increase species diversity potential of maintenance. habitat types and types and species - Changes to flood risk the habitat types and within the SNCI. increasing habitat species diversity diversity within the management can affect the species diversity types and species landscape, its character and within the SNCI. SNCI. However, this within the SNCI. diversity within the value as an amenity. However, this would would occur in an SNCI. occur in an unmanaged way. unmanaged and uncontrolled way.

Environment Agency River Adur CFMP - Appendix B (September 2008) 99 Does this policy change flood risk locally or elsewhere: Risk downstream Risk downstream Risk downstream Impact uncertain Impact uncertain will increase due to NA likely to increase likely to increase climate change

Environment Agency River Adur CFMP - Appendix B (September 2008) 100 Form B7 – Summary of losses and gains.

Policy unit Policy Unit 3 - Steyning and Upper Beeding name/number:

Preferred policy Policy options Losses Gains option relative to current baseline Policy option P1 Environmental NO LOSSES HIGH+ Not preferred option – There are limited gains The area of the River under this policy option. Adur Meadows and The numbers of people Wyckham Wood SNCI and properties will significantly adversely affected by increase by more than 2 removing FRM are 1km but in an unacceptably high. The unmanaged and AAD are also high and uncontrolled way the environmental

effects are Social HIGH- NO GAINS unpredictable due to the The number of people unmanaged and and properties at risk of uncontrolled nature of

localised fluvial flooding this policy option. in a 1% AEP flood event will increase by more

than 95 and 28 respectively The number of

properties at risk of surface water and urban drainage flooding will

increase significantly Withdrawing the flood warning system will

increase risk to human life The length of A road at

risk from a 1% AEP flood event will increase by more than 0.44km

The number of critical infrastructure at risk from a 1% AEP flood event

will increase Substantially more surface water and urban

drainage flooding to critical infrastructure and transport routes will

occur

Economic HIGH- NO GAINS

The AAD to properties and agricultural land caused by fluvial

Environment Agency River Adur CFMP - Appendix B (September 2008) 101 flooding will increase by more than £414,000 AAD to properties and agricultural land caused by surface water flooding will significantly increase The balance of FRM expenditure to AAD is unacceptable with AAD to properties and agricultural land increasing by more than £364,200 Policy option P2 Environmental NO LOSSES HIGH+ Not preferred option – There are limited gains The area of the River under this policy option. Adur Meadows and The numbers of people Wyckham Wood SNCI and properties will significantly adversely affected by increase by more than 2 removing FRM are 1km but in an unacceptably high. The unmanaged way AAD are also high and

the environmental Social HIGH- NO GAINS effects are The number of people unpredictable due to the and properties at risk of unmanaged and

localised fluvial flooding uncontrolled nature of in a 1% AEP flood event this policy option. will increase by more

than 70 and 18 respectively The number of

properties at risk of surface water and urban drainage flooding will

increase significantly The length of A road at risk from a 1% AEP

flood event will increase by more than 0.44km The number of critical

infrastructure at risk from a 1% AEP flood event will increase

Substantially more surface water and urban drainage flooding to

critical infrastructure and transport routes will occur

HIGH- Economic NO GAINS The AAD to properties and agricultural land caused by fluvial flooding will increase by more than £244,000 Environment Agency River Adur CFMP - Appendix B (September 2008) 102 AAD to properties and agricultural land caused by surface water flooding will significantly increase The balance of FRM expenditure to AAD is unacceptable with AAD to properties and agricultural land increasing by more than £224,200 Policy option P3 Environmental NO LOSSES MEDIUM+ Preferred Policy Option – Although there are The area of the River some losses in terms of Adur Meadows and the numbers of people Wyckham Wood SNCI and properties and the will increase by 2 level of disruption and approximately 1km in AAD caused by the future flooding, the overall

strategy for this CFMP Social LOW- NO GAINS is to increase flood storage upstream and The number of people thereby mitigate against and properties at risk of future increases in flood localised fluvial flooding risk due to climate in a 1% AEP flood event change. will increase in the future

by approximately 55 and 13 respectively The number of

properties at risk of surface water and urban drainage flooding will

increase in the future The length of A road and number of critical

infrastructure at risk from a 1% AEP flood event will increase only slightly

A minor increase in surface water and urban drainage flooding to

critical infrastructure and transport routes will occur in the future

Economic MEDIUM- LOW+

The AAD to properties The balance of FRM and agricultural land expenditure to AAD caused by fluvial will remain acceptable flooding will increase by with AAD to properties approximately £120,000 and agricultural land AAD to properties and increasing by agricultural land caused approximately by surface water £119,200 in the future flooding will increase slightly in the future

Environment Agency River Adur CFMP - Appendix B (September 2008) 103 Policy option P4 Environmental NO LOSSES LOW+ Not preferred option – Although there are The area of the River additional benefits in Adur Meadows and terms of the numbers of Wyckham Wood SNCI people and properties will remain the same and reducing the level of with no increases in disruption and AAD biodiversity caused by flooding, the

overall strategy for this Social NO LOSSES HIGH+ CFMP is to increase flood storage upstream The number of people and thereby mitigate and properties at risk against future increases of localised fluvial in flood risk due to flooding in a 1% AEP climate change. It flood event will not should therefore be increase in the future unnecessary to further The number of increase FRM in this properties at risk of policy unit in order to surface water and ensure risk does not urban drainage increase. flooding will not

increase in the future The length of A road and number of critical

infrastructure at risk from a 1% AEP flood event will not increase

in the future Surface water and urban drainage

flooding to critical infrastructure and transport routes will

not increase in the future

Economic NO LOSSES HIGH+

Environment Agency River Adur CFMP - Appendix B (September 2008) 104 Policy option P5 Environmental MEDIUM- NO GAINS Not preferred option – Although there are The area of the River significant benefits in Adur Meadows and terms of the numbers of Wyckham Wood SNCI people and properties will be decreased and minimising the level

of disruption and AAD

caused by flooding, the Social NO LOSSES HIGH+ overall strategy for this The number of people CFMP is to increase and properties at risk flood storage upstream

of localised fluvial and thereby mitigate flooding in a 1% AEP against future increases flood event will be in flood risk due to

reduced by more than climate change. It 90 and more than 92 should therefore be respectively unnecessary to further

The number of increase FRM in this properties at risk of policy unit in order to surface water and ensure risk does not

urban drainage increase. flooding will be reduced to 0

The length of A road and number of critical infrastructure at risk

from a 1% AEP flood event will be reduced to 0

Surface water and urban drainage flooding to critical

infrastructure and transport routes will not occur in the future

Economic MEDIUM- HIGH+

The balance of FRM The AAD to properties expenditure to AAD will and agricultural land be unacceptable with caused by fluvial significant increases in flooding will be FRM expenditure to reduced reduce AAD to AAD to properties and properties and agricultural land agricultural land by more caused by surface than £75,800 water flooding will be minimal Policy option P6 Environmental Not applicable Not applicable Not preferred option – this Policy Option is not

considered feasible in Social this policy unit.

Economic

Key Environment Agency River Adur CFMP - Appendix B (September 2008) 105 HIGH: High negative A policy has a ‘high negative’ effect where it could contribute to a social, economic or environmental objective in a significantly negative way. A ‘high negative’ effect could be: (i) a very large increase in current flood risk; (ii) very large projected increases in flood risk under future conditions, and/or; (iii) significant additional social, economic and/or environmental losses. MEDIUM: Medium negative A policy has a ‘medium negative’ effect where it could contribute to a social, economic or environmental objective in a negative way. A ‘medium negative’ effect could be: (i) an increase in current flood risk; (ii) a projected increase in flood risk under future conditions, and/or; (iii) social, economic and/or environmental losses. LOW: Low negative A policy has a ‘low negative’ effect where it could make a limited contribution to a social, economic or environment objective, but where the overall contribution would be negative. A ‘low negative’ effect could be: (i) an overall increase in current flood risk; (ii) an overall increase in flood risk under future conditions, and/or; (iii) overall social, economic and/or environmental losses. NEUTRAL: Neutral A policy has a ‘neutral’ effect where it makes neither a positive or negative contribution to a social, economic or environmental objective. A ‘neutral’ effect could be: (i) no change in current level of risk. In this instance the current level of risk would have to be low, so that the residual risk after a neutral policy was implemented remained acceptable; (ii) no change in flood risk under future conditions. In this instance projected future risk would need to be low so that the residual risk after a neutral policy was implemented remained acceptable, and/or; (iii) no additional social, economic and/or environmental gains or losses. Policy options may also be ‘neutral’ where they are not relevant in a particular policy unit, or where it is not feasible for a policy option to contribute to an objective. HIGH: High positive A policy has a ‘high positive’ effect where it could contribute to a social, economic or environmental objective in a significantly positive way. A ‘high positive’ effect could be: (i) a very large reduction in current flood risk; (ii) avoiding/reducing very large projected increases in flood risk under future conditions, and/or; (iii) significant additional social, economic and/or environmental gains. MEDIUM: Medium positive A policy has a ‘medium positive’ effect where it could contribute to a social, economic or environmental objective in a positive way. A ‘medium positive’ effect could be: (i) a reduction in current flood risk; (ii) avoiding/reducing projected increases in flood risk under future conditions, and/or; (iii) additional social, economic and/or environmental gains. LOW: Low positive A policy has a ‘low positive’ effect where it could make a limited contribution to a social, economic or environment objective, but where the overall contribution would be positive. A ‘low positive’ effect could be: (i) an overall reduction in current flood risk; (ii) an overall avoidance/reduction in flood risk under future conditions,

Environment Agency River Adur CFMP - Appendix B (September 2008) 106

Form B8 Summary of preferred policy Policy unit 3 – Steyning and Upper Beeding Physical characteristics: - Urban area of Steyning and Upper Beeding villages, which are separated laterally by the Lower River Adur. - The unit overlies weald clay to the north and chalk to the south, and has very subdued topography. - Lies at the northern base of the South Downs escarpment and the majority of the unit lies within the proposed South Downs National Park designated area. Flood mechanism: - Land behind the defences becomes seasonally waterlogged, resulting in flashy responses to rainfall. - Combination of surface water run-off, urban drainage and under capacity of local streams causing localised fluvial flooding and urban flooding. - Overtopping of raised river embankments along the River Adur – will generally not overtop due to fluvial flooding on its own, requires significant tidal influence. Receptor: - People, properties and infrastructure in Steyning and Upper Beeding. - A small number of listed buildings and heritage sites (salterns) lie in the floodplain. Problem/risk - Currently 91 properties are at risk of fluvial flooding in the policy unit from the 1% annual probability fluvial flood event. - The flood risk increases slightly changes over the next 100 years. - Surface water flooding is likely to increase more significantly than fluvial flooding. Current Flood Risk Summary Number of properties at risk of flooding (1% annual probability flood event) 91 Total damages (approx.) (1% annual probability flood event) £2.951 million Annual averages damages (approx.) £80,000 Future Flood risk: - Flood risk from surface water flooding and urban drainage problems is currently assessed as low, assessment changes to low to medium in the future. - Flood risk from fluvial flooding is currently assessed as low, assessment changes to medium in the future. Future Flood Risk Summary (in 100 years time) Number of properties at risk of flooding (1% annual probability flood event) 112 Total damages (approx.) (1% annual probability flood event) £3.711 million Annual averages damages (approx.) £206,000 Policy 3 - Continue with existing or alternative actions to manage flood risk at the current Policy selected level (accepting that flood risk with increase over time from this baseline). This policy is appropriate where the current level of flood risk management is considered acceptable. Current management and maintenance activities include maintaining defences, grass and weed cutting, debris removal cutting back overhanging branches. It is recognised that flood risk will change in the future, and management actions may change in time to gain efficiencies or improve effectiveness. This policy is appropriate for this policy unit for the following reasons: - The current level of flood risk is low and it is not expected to increase greatly in the Justification future. - The consequences of flooding are relatively low. - The current flood risk management activities, carried out for the localised fluvial and surface water and urban drainage flooding problems, are considered appropriate and acceptable for the level of risk. - The selected policy would help achieve the catchment objectives to ensure the impact of flooding does not significantly increase. - This policy unit will also benefit from the policy 6 option adopted for policy unit 1. - Ensure flood damages do not significantly increase in Steyning and Upper Beeding due to future change (urban development and climate change). - Ensure that river channel and flood defence maintenance expenditure is appropriate to the property economic damage in urban areas from flooding. Catchment - Ensure the impact of flooding on people and property does not significantly increase in objectives Steyning and Upper Beeding in the future. - Ensure the disruption caused by flooding to transport and critical infrastructure does not increase in Steyning and Upper Beeding in the future. - Protect and enhance the River Adur Water Meadows and Wyckham Wood Site of Nature Conservation Importance.

Environment Agency River Adur CFMP - Appendix B (September 2008) 107 Opportunities: - Provide development control advice to ensure no increase in run-off from new development. - Reduce flood risk and improve water quality by promoting and encourage the use of SuDS in proposed developments. - Investigate removal of Environment Agency owned and maintained existing raised defences to reinstate the floodplain between Partridge Green and Steyning and between Steyning and Shoreham to a naturally functioning state, to provide flood storage and enhance conservation value and biodiversity. - Improvements in the efficiency of channel and flood defence maintenance processes. - Effective and efficient use of developer contributions for flood risk management. - Help meet national biodiversity action plan (BAP) targets.

Constraints: - Government and international legislation, environmental management policies, plans and Catchment-wide strategies for the catchment must be complied with, such as accommodating new opportunities housing within the catchment as detailed by the South East Plan and compliance with and constraints the Habitats Directive. - Steep catchments of the South Downs result in rapid run-off and quick responses to rainfall events. - Available funding for the initial set up of new flood risk management schemes. - Older flood defence structures are likely to be more costly to maintain. - Limited available information on surface water and groundwater flood damages. - Visual impact of flood risk management activities within the proposed National Park or Areas of Outstanding Natural Beauty. - Transport links in the catchment are a vital part of the communication network regionally, nationally and internationally, in particular the railways connecting London to the south coast and connecting the coastal towns and cities, the A23, A24, A27, A259, A283 and A2032. - Some environmentally designated habitats are susceptible to changes in flood frequency, floodwater chemistry, groundwater levels and drainage system maintenance. - Changes to flood risk management can affect the landscape, its character and value as an amenity. Policy 1 - do nothing. The urban areas of Steyning, Upper Beeding and Bramber currently have a low level of risk of flooding. However the risk of flooding from surface water and rivers may increase with climate change. Without continued maintenance the average annual damages would increase to more than £500,000. Do nothing is, therefore, not an appropriate policy.

Policy 2 - reduce current level of flood risk management. As with policy option 1, the potential damages and losses would become unacceptable in the future under a ‘do less’ Alternative policy. The average annual damages would increase to more than £330,000. policies considered Policy 4 – maintain the current level of flood risk into the future. This policy could also apply, however, it implies increasing flood risk management costs to more than £60,000 p.a. in the future. The need for this has not been identified or considered justifiable.

Policy 5 - reduce the level of flood risk, both now and in the future. The current level of risk is adequately managed and therefore this policy is not justified.

Policy 6 - increase flooding to reduce flooding elsewhere. There are no opportunities within this policy unit for this policy. We have estimated the future increase in flood risk within this policy unit on the best available prediction we have of climate change (at the time of the assessment), frequency and size of storms and flood events in the future.

Uncertainties The broadscale modelling has shown that by increasing the flooding in policy units upstream and there is a small reduction in flood risk in this policy unit (approximately 5%). We will need dependencies more detailed studies to find out if it is practical to do this.

Delivering this policy will partly depend on developing and implementing an effective urban drainage strategy in partnership with the local drainage authority, highway department, water and sewerage company and other relevant authorities or responsible parties.

Environment Agency River Adur CFMP - Appendix B (September 2008) 108 Form B9 Requirements for further policy development and appraisal Policy unit 3 – Steyning and Upper Beeding Is there a need for further policy development? No If yes, then mark policy options for more detailed development. Some complex policies may require more detailed development, probably at Strategy Plan level. Is there a need for further more detailed appraisal? Yes If yes, take forward to strategy study.

Environment Agency River Adur CFMP - Appendix B (September 2008) 109

Form B10 Indicators for monitoring, review and evaluation This form sets out the indicators that need to be included in the policy implementation plan, for policy monitoring, drawing on the residual risks and likely impacts identified above. This will allow better review and evaluation of the policy when implemented. Policy unit 3 – Steyning and Upper Beeding Indicators to be included in policy unit 3 implementation plan are:

Economic - Total annual average damages (to properties and agriculture) from fluvial flooding (£AAD). - Estimated damages resulting from surface water flooding (£) (based on historical damages). - Balance of annual flood risk maintenance expenditure (£) to annual average damages from fluvial flooding to property (£).

Social - Number of people and properties affected by the 1% annual probability fluvial flood event. - The estimated number of properties affected by surface water flooding (based on historical records). - Length of A road and railway line (km) affected by the 1% annual probability fluvial flood event. - Number of critical infrastructure sites affected by the 1% annual probability fluvial flood event. - Number and period of recorded A road and railway closures due to surface water flooding (based on historical records). - Number of critical infrastructure sites recorded as being affected by surface water flooding (based on historical records).

Environmental - Habitat quality and species diversity.

Environment Agency River Adur CFMP - Appendix B (September 2008) 110

Policy unit 4 South Downs (West) Policy appraisal forms Form B5 – Summary of current and future levels of and responses to flood risk. Form B6 – Appraisal of policy options against policy unit objectives. Form B7 – Summary of losses and gains. Form B8 – Summary of preferred policy. Form B9 – Requirements for further policy development and appraisal. Form B10 – Indicators for monitoring, review and evaluation.

Environment Agency River Adur CFMP - Appendix B (September 2008) 111

Form B5 Summary of current and future levels or and responses to flood risk Policy unit 4 – South Downs (West) Defences: There are no formal flood defences in this policy unit.

Flood warning: This policy unit is not covered by a fluvial flood warning area. There are no properties connected to the flood warning direct service. Current responses to flood risk

within the policy unit Maintenance: The Soil Society periodically inspects the land east of Findon Valley to ensure continued preservation of soil. The estimated annual cost of maintenance undertaken by the Environment Agency within this policy unit is approximately £1,000. Standards of service that apply Standard of protection: There is no formal raised flood defences within this to flood defences within the policy unit. policy unit In 10% flood In 1% flood In 0.1% flood Receptors outline* outline* outline* Residential properties 0 0 0 Commercial properties 0 0 0 Population 0 0 0 Property damages 0 0 N/A Agricultural damages 0 £455 N/A A roads 0 km 0 km 0.33 km Railways 0 km 0 km 0 km Agricultural land Grade 1 0 km2 0 km2 0 km2 Agricultural land Grade 2 0 km2 0 km2 0 km2 What is currently exposed to 2 2 2 flooding? Agricultural land Grade 3 0 km 0.02 km 0.04 km Agricultural land Grade 4 0 km2 0 km2 0 km2 Agricultural land Grade 5 0 km2 0 km2 0 km2 SNCIs 0 km2 0 km2 0 km2 SSSI 0 km2 0 km2 0 km2 Listed Buildings 0 0 0 SM 0 0 0 AONB 0 km2 0.02 km2 0.04 km2 ESA 0 km2 0.02 km2 0.04 km2 Registered Historic Parks 2 2 2 and Gardens 0 km 0 km 0 km Proposed National Park 0 km2 0.02 km2 0.04 km2 * 10% and 1% based on broadscale model results and 0.1% based on Flood Zone 2 Economic and social receptors: There are no residential or commercial properties within the 1% annual probability flood event outline.

A very small area of moderate grade agricultural land (Grade 3) is at risk of flooding for the 1% annual probability flood event.

Environmental designations: No extent of internationally or nationally designated sites, SSSIs or SNCIs is at Who and what are currently risk of flooding from the 10%, 1% or 0.1% annual probability flood event within most vulnerable to flood this policy unit. damage and losses?

Landscape: Less than 0.05km2 of the Sussex Downs AONB, Sussex Downs ESA and proposed South Downs National Park lies within the 1% and 0.1% annual probability flood event outlines.

Natural and Historic Environment: There are no listed buildings, registered historic parks and gardens or SMs at risk of flooding for the considered annual probability flood events in this policy unit. What are the key factors that Land use changes contributing to increase in soil erosion, such as changes in could drive future flood risk? crop type and increases in livestock stocking density. What are the possible future Flood risk is currently assessed as low, and it is not expected to increase under levels of flood risk under the future scenarios. main scenarios? Environment Agency River Adur CFMP - Appendix B (September 2008) 112 What potential responses (or groups of responses) are Potential to work with professional partners to derive better land management being considered to manage options so that run-off can be reduced and soil erosion avoided. flood risk? There is uncertainty about how effective changes in land management and vegetation cover will be in altering run-off at the catchment scale. It is known to What gaps and uncertainties work locally, but we do not yet know its effect on the catchment as a whole. are there in knowledge, and

what assumptions have been The understanding of the impact of climate change on groundwater is still in its made? infancy, and there is still a lot of uncertainly surrounding the impact on groundwater flooding events.

There is no flood risk within this policy unit, however, it does contribute to groundwater flooding and surface water run-off in neighbouring policy units. We have not been able to model these processes and it has therefore not been possible to define generic responses in this policy unit.

Environment Agency River Adur CFMP - Appendix B (September 2008) 113 Form B6 Appraisal of policy options against policy unit objectives Policy unit 4 – South Downs (West) KEY = Scale of policy impact on objective: Not appraised Baseline Meets objective No impact Doesn’t meet object Uncertain The preferred policy option is indicated below by the policy option highlighted in pink Baseline (current Policy 1 Policy 2 Policy 3 Policy 4 Policy 5 Policy 6 and future) Improved land use management through No maintenance of agri-environment watercourses. schemes would Channels become reduce surface run-off blocked with Reduction in Introduce by woodland creation vegetation and maintenance of Improved level of management Current and future to increase conveyance is watercourses. channel maintenance practices that allow baseline with current Maintenance of the interception of run-off reduced. Channels become of watercourses. greater water flood risk channels continues. and increase blocked with vegetation retention within the management. Localised protection infiltration. A do nothing and conveyance is policy unit i.e. change measures introduced. approach would reduced. in land use. There is potential to increase the flooding increase water in an unmanaged and retention by unpredictable way. Catchment Targets and Opportunities and introducing flood objectives Indicators Constraints storage areas. Economic objectives The level of channel and flood defence maintenance The current annual expenditure is likely to The level of channel Targets channel and flood remain the same or be and flood defence Maintain a suitable defence maintenance slightly less than Channel and flood maintenance The level of channel balance of annual river Opportunities expenditure is No channel and flood £1,000 as agri- - Improvements in the Channel and flood defence maintenance expenditure will and flood defence channel and flood approximately £1,000; defence maintenance environment schemes efficiency of channel and defence maintenance expenditure remains increase over time to maintenance defence maintenance flood defence maintenance the annual average expenditure is reduce the level of expenditure reduces to at approximately mitigate the affects of expenditure will Ensure that river expenditure (£) to processes. damages from fluvial incurred as no management required. - To work with Defra and be less than £1,000. £1,000. Annual climate change to increase to be more channel and flood annual average flooding to agriculture maintenance is Annual average farmers to produce soil Annual average average damages slightly more than than £1,000. Annual defence maintenance damages from fluvial are currently less than undertaken. Annual damages from fluvial management plans which damages from fluvial from fluvial flooding to £1,000. Annual average damages expenditure is flooding to agriculture have a benefit to flood risk £100. Annual average average damages flooding to agriculture flooding to agriculture agriculture increase average damages from from fluvial flooding appropriate to the (£). through reducing the run-off damages from fluvial from fluvial flooding are likely to remain rate. are likely to be around over time due to the fluvial flooding to to agriculture are agricultural economic flooding to agriculture to agriculture less than £100. Constraints £1,000. affects of climate agriculture will remain estimated to be £0. damage in rural areas Indicators - Available funding for the are unlikely to increase to be more change to be around less than £100. from flooding. Balance of annual river initial set up of new flood risk significantly increase, than £2,000. The balance of management schemes. The balance of £150. The balance of channel and flood being less than £150 expenditure to - Older flood defence expenditure to With better expenditure to defence maintenance in the future. The balance of damages will remain structures are likely to be damages becomes The balance of maintenance efficiency damages will be expenditure (£) to more costly to maintain. expenditure to acceptable. - unacceptable over expenditure to and effective use of unacceptable with annual average Limited available information The current balance of damages is on surface water and time. damages will remain funding the balance of expenditure being damages from fluvial expenditure to unacceptable. In addition policy unit groundwater flood damages. acceptable. expenditure to unjustifiably high. flooding to agriculture damages is 5 is likely to benefit damages will remain (£). considered from the agri- acceptable. acceptable. environmental schemes, which should reduce muddy flooding. Social objectives

Environment Agency River Adur CFMP - Appendix B (September 2008) 114 Ensure the impact of Targets Opportunities No maintenance of - Reduce flood risk and flooding on people No significant increase improve water quality by channels and and property does not in the number of people promoting and encouraging drainage networks or properties affected by the use of SuDS in the would result in an significantly increase Approximately 0 the 1% annual proposed urban increase in the in the future (for developments in Brighton people and 0 probability fluvial flood frequency, extent and It is likely that the The increased and Hove, Worthing, properties are at risk No people and No people and example due to event or surface water Shoreham and Burgess Hill. depth of localised number of people and No people and frequency of flooding of localised fluvial properties are likely to properties are likely climate change). flooding in the future fluvial flooding. properties at risk of properties are likely to will be managed such flooding by the current be at risk of localised to be at risk of Constraints localise fluvial flooding be at risk of localised that the number of - Government and international 1% annual probability fluvial flooding by the localised fluvial Indicators The number of may increase to be fluvial flooding by the properties at risk in legislation, environmental flood event. This is 1% annual probability flooding by the 1% Number of people and management policies, plans people and properties more than zero. 1% annual probability this policy unit is not not anticipated to flood event annual probability properties affected by and strategies for the at risk of localise flood event increased from the catchment must be complied increase the future. flood event the 1% annual flooding will increase There is no flood current baseline and with, such as accommodating There is no flood probability fluvial flood new housing within the to be more than 23 warning service Flood Warning Service There is no flood There are currently no warning service Flood Warning event catchment as detailed by the and 10 respectively. available, which may is introduced. warning service properties covered by available. Service is introduced. South East Plan and result in increased risk available. compliance with the Habitats a flood warning Coverage of Flood There will be no flood to human life. Directive. service. Warning Service - Visual impact of flood risk warning system management activities within which may result in the proposed National Park or Areas of Outstanding increased risk to Natural Beauty. human life. Environmental objectives Introducing management practices that The area of the increase water Sussex Downs retention and reduce There is currently 2 AONB and South run-off within the 0.02km of the Sussex The area of the Sussex The area of the Downs ESA and catchment is likely to Downs AONB and Downs AONB and Sussex Downs AONB The area of the Sussex proposed National reduce frequency and South Downs ESA South Downs ESA and and South Downs Downs AONB and The landscape Park located within depth of flooding and Targets and proposed National proposed National Park ESA and proposed South Downs ESA and character of the Opportunities the 1% annual therefore have a Increase the landscape - Help meet national Park located within the located within the 1% National Park located proposed National Park Sussex Downs AONB probability flood negative impact on character value of the biodiversity action plan (BAP) 1% annual probability annual probability flood within the 1% annual located within the 1% and South Downs targets. event outline the landscape Sussex Downs AONB flood event outline. event outline increases probability flood event annual probability flood ESA and proposed Increase the landscape Constraints increases to be more character of the and South Downs ESA - Some environmentally This increases by a 2 to be slightly more than outline increases over event outline remains National Park can be character value of the than 0.05km . 2 2 Sussex Downs and proposed National designated habitats are minor extent over time 0.032km . time to at around at around 0.02km . enhanced with the Sussex Downs AONB susceptible to changes in 2 AONB and South Park. to approximately 0.032km . implementation of and South Downs ESA flood frequency, floodwater 2 The landscape Downs ESA and 0.032km in the future. The landscape There would be no considered flood risk and proposed National chemistry, groundwater character of the proposed National Indicators levels and drainage system character of the There would be no impact on the management Park. Sussex Downs Park. Landscape character maintenance. The landscape Sussex Downs AONB notable impact on the landscape character of practices, such as - Changes to flood risk AONB and South assessment of the character of the and South Downs ESA landscape character the Sussex Downs increasing the flood management can affect the Downs ESA and The area of the AONB, ESA and landscape, its character and Sussex Downs AONB and proposed National of the Sussex Downs AONB and South storage areas, in a proposed National Sussex Downs proposed National Park. value as an amenity. and South Downs Park is likely to alter in AONB and South Downs ESA and managed and Park is likely to alter AONB and South ESA and proposed a beneficial manner, Downs ESA and proposed National Park controlled way. in a beneficial Downs ESA and National Park is however, it will occur in proposed National in this policy unit. manner, however, it proposed National unlikely to notable an unmanaged way. Park in this policy unit. will occur in an Park located within alter. unmanaged and un the 1% annual controlled way. probability flood event outline decreases to be minimal. Policy unit 5 is likely Does this policy change flood risk locally or elsewhere: Policy unit 5 is likely to Impact uncertain, to benefit from Impact uncertain, but benefit from the agri- but no significant No significant No significant impact increased water no significant impact environmental impact on adjacent impact on adjacent on adjacent policy retention and schemes, which on adjacent policy reduced run-off, policy units policy units. units. should reduce muddy units anticipated. which should reduce anticipated. flooding. muddy flooding.

Environment Agency River Adur CFMP - Appendix B (September 2008) 115 Form B7 – Summary of losses and gains.

Policy unit Policy Unit 4 - South Downs (West) name/number:

Preferred policy Policy options Losses Gains option relative to current baseline Policy option P1 Environmental NO LOSSES MEDIUM+ Not preferred option – Although the benefits to The landscape value the environment are of the Sussex Downs potentially high, AONB and South alterations to the Downs ESA/proposed landscape will be NP are likely to be unmanaged and beneficially altered but uncontrolled and in an unmanaged and therefore unpredictable. uncontrolled way In addition to this, the

AAD to agricultural land Social MEDIUM- NO GAINS resulting from this policy The number of people will be unacceptably and property at risk high.

significantly increases.

Economic HIGH- NO GAINS

The balance of FRM expenditure to AAD is unacceptable with AAD to agricultural land increasing by more than £900 Policy option P2 Environmental NO LOSSES MEDIUM+ Not preferred option – Although the benefits to The landscape value the environment are of the Sussex Downs potentially high, AONB and South alterations to the Downs ESA/proposed landscape will be NP are likely to be unmanaged and beneficially altered but uncontrolled and in an unmanaged way therefore unpredictable.

In addition to this, the

AAD to agricultural land Social MEDIUM- NO GAINS resulting from this policy The number of people will be unacceptably and property at risk high.

significantly increases.

Economic HIGH- NO GAINS

The balance of FRM expenditure to AAD is unacceptable with AAD to agricultural land increasing by more than

Environment Agency River Adur CFMP - Appendix B (September 2008) 116 £900 Policy option P3 Environmental NO LOSSES LOW+ Not preferred option – The potential benefits in The areas of the terms of the Sussex Downs AONB environment are not and South Downs sufficiently optimised ESA/proposed NP that under this policy. In fall within the 1% AEP addition to this, the AAD will increase slightly to agricultural land will but with no notable increase significantly in increase in landscape the future. value

Social NO LOSSES NO GAINS

Economic NO LOSSES LOW+

The balance of FRM expenditure to AAD will remain acceptable with AAD to agricultural land increasing slightly in the future Policy option P4 Environmental LOW- NO GAINS Not preferred option – Although AAD to The areas of the Sussex agricultural land will not Downs AONB and South increase in the future, Downs ESA/proposed opportunities to bring NP that fall within the benefits to the 1% AEP remain the environment are not same with no increase in sufficiently optimised landscape value under this policy.

Social NO LOSSES NO GAINS

Economic NO LOSSES MEDIUM+

The balance of FRM expenditure to AAD will remain acceptable with slight increases in FRM expenditure to maintain AAD to agricultural land at current levels in the future Policy option P5 Environmental MEDIUM- NO GAINS Not preferred option – There are no gains The areas of the Sussex under this policy option. Downs AONB and South FRM expenditure is Downs ESA/proposed unacceptably high and NP that fall within the there will be negative 1% AEP will be impacts on the decreased which will Environment Agency River Adur CFMP - Appendix B (September 2008) 117 impact negatively on the landscape value of the landscape value area.

Social NO LOSSES NO GAINS Economic HIGH- NO GAINS

The balance of FRM expenditure to AAD is unacceptable with significant increases in FRM expenditure to reduce AAD to agricultural land Policy option P6 Environmental NO LOSSES HIGH+ Preferred Policy Option – There are no losses The landscape value under this policy option. of the Sussex Downs The potential benefits to AONB and South landscape value are Downs ESA/proposed maximised and will be NP will be enhanced in carried out in a a managed and managed and controlled controlled way way. The balance

between FRM and AAD

to agricultural land will Social NO LOSSES NO GAINS be optimised. Encouraging increased uptake of agri- Economic NO LOSSES HIGH+ environment schemes The balance of FRM will further reduce the expenditure to AAD AAD to land. will remain acceptable Implementing policy with reductions in FRM option 6 in this part of expenditure and AAD the catchment will also to agricultural land due bring strategic benefits to agri-environment to policy units schemes and targeted downstream through FRM increased floodwater storage.

Key HIGH: High negative A policy has a ‘high negative’ effect where it could contribute to a social, economic or environmental objective in a significantly negative way. A ‘high negative’ effect could be: (i) a very large increase in current flood risk; (ii) very large projected increases in flood risk under future conditions, and/or; (iii) significant additional social, economic and/or environmental losses. MEDIUM: Medium negative A policy has a ‘medium negative’ effect where it could contribute to a social, economic or environmental objective in a negative way. A ‘medium negative’ effect could be: (i) an increase in current flood risk; (ii) a projected increase in flood risk under future conditions, and/or; (iii) social, economic and/or environmental losses. LOW: Low negative A policy has a ‘low negative’ effect where it could make a limited contribution to Environment Agency River Adur CFMP - Appendix B (September 2008) 118 a social, economic or environment objective, but where the overall contribution would be negative. A ‘low negative’ effect could be: (i) an overall increase in current flood risk; (ii) an overall increase in flood risk under future conditions, and/or; (iii) overall social, economic and/or environmental losses. NEUTRAL: Neutral A policy has a ‘neutral’ effect where it makes neither a positive or negative contribution to a social, economic or environmental objective. A ‘neutral’ effect could be: (i) no change in current level of risk. In this instance the current level of risk would have to be low, so that the residual risk after a neutral policy was implemented remained acceptable; (ii) no change in flood risk under future conditions. In this instance projected future risk would need to be low so that the residual risk after a neutral policy was implemented remained acceptable, and/or; (iii) no additional social, economic and/or environmental gains or losses. Policy options may also be ‘neutral’ where they are not relevant in a particular policy unit, or where it is not feasible for a policy option to contribute to an objective. HIGH: High positive A policy has a ‘high positive’ effect where it could contribute to a social, economic or environmental objective in a significantly positive way. A ‘high positive’ effect could be: (i) a very large reduction in current flood risk; (ii) avoiding/reducing very large projected increases in flood risk under future conditions, and/or; (iii) significant additional social, economic and/or environmental gains. MEDIUM: Medium positive A policy has a ‘medium positive’ effect where it could contribute to a social, economic or environmental objective in a positive way. A ‘medium positive’ effect could be: (i) a reduction in current flood risk; (ii) avoiding/reducing projected increases in flood risk under future conditions, and/or; (iii) additional social, economic and/or environmental gains. LOW: Low positive A policy has a ‘low positive’ effect where it could make a limited contribution to a social, economic or environment objective, but where the overall contribution would be positive. A ‘low positive’ effect could be: (i) an overall reduction in current flood risk; (ii) an overall avoidance/reduction in flood risk under future conditions,

Environment Agency River Adur CFMP - Appendix B (September 2008) 119

Form B8 Summary of preferred policy Policy unit 4 – South Downs (West) Physical characteristics: - Steep scarp slopes of the chalk downland hills extend the entire width of the CFMP area. - Environmentally Sensitive Area and Area of Outstanding Natural Beauty. - Spring line on the southern slopes forms the headwaters of the Teville Stream and Ferring Rife. - Shallow silty soils are well drained and the chalk is an important local aquifer for water supply. - Proposed National Park with high amenity value and landscape character. - Contains a significant proportion of Scheduled Monuments and SSSIs in the CFMP area. Flood mechanism: - No fluvial flooding within the policy unit. - Land management affects runoff rates with certain types of management causing muddy floods in adjacent urban areas. Receptor: Problem/risk - None within the policy unit. - Adjacent urban areas (particularly in Policy Unit 5 (Worthing)) are receptors of flooding generated due to land management in this unit. Current Flood Risk Summary Number of properties at risk of flooding (1% annual probability flood event) 0 Total damages (approx.) (1% annual probability flood event) £455 Less than Annual averages damages (approx.) £100 Future Flood risk: - Flood risk is currently assessed as low, and it is not expected to increase under future scenarios. Future Flood Risk Summary (in 100 years time) Number of properties at risk of flooding (1% annual probability flood event) 0 Total damages (approx.) (1% annual probability flood event) £965 Less than Annual averages damages (approx.) £150 Policy 6 - Take action to increase the frequency of flooding to deliver benefits locally or Policy selected elsewhere, which may constitute an overall flood risk reduction (for example for habitat inundation). This policy can deliver benefits for people and the environment locally or in other policy units. By increasing flooding and infiltration of rainwater locally in this unit, flooding downstream can be reduced. The changes in land management can also benefit biodiversity. Current maintenance activities include grass and weed cutting. Policy 6 sets a framework that actively supports increased flooding and infiltration of rainwater and is appropriate to this policy unit for the following reasons: - Although flood risk is assessed as low within the policy unit, there is the opportunity to reduce flood risk in adjoining units. - Large rural policy unit presents opportunities for changing land use and developing possible flood storage mechanisms to reduce rapid run-off generated from land use Justification activities and the steep slopes. - Action in this unit will help reduce risk of muddy floods in places such as Findon. - There are some opportunities for reducing downstream flooding by improving or creating new habitats, which increase water retention. - Soil erosion problems can best be tackled through more sensitive land management land use change and changes in farming practices. - Increased storminess due to climate change may increase soil erosion and localised flash flooding in neighbouring catchments. - This policy would help meet the environmental and landscape objectives by working with landowners and the Government. - Ensure that river channel and flood defence maintenance expenditure is appropriate to Catchment the agricultural economic damage in rural areas from flooding. objectives - Increase the landscape character value of the Sussex Downs AONB and South Downs ESA and proposed National Park. Catchment-wide Opportunities: opportunities - Improvements in the efficiency of flood defence maintenance processes.

Environment Agency River Adur CFMP - Appendix B (September 2008) 120 and constraints - To work with Defra and farmers to produce soil management plans which have a benefit to flood risk through reducing the run-off rate. - Help meet national biodiversity action plan (BAP) targets.

Constraints: - Available funding for the initial set up of new flood risk management schemes. - Limited available information on surface water and groundwater flood damages. - Some environmentally designated habitats are susceptible to changes in flood frequency, floodwater chemistry, groundwater levels and drainage system maintenance. - Changes to flood risk management can affect the landscape, its character and value as an amenity. Policy 1 - do nothing. Although this could be considered as a possible policy option, and would have a similar long-term result as policy 6, it would limit the opportunities to reduce soil erosion and surface water run-off that affect neighbouring policy units.

Policy 2 - reduce current level of flood risk management. There is already minimal flood risk management within this policy unit. It is not possible to reduce it further.

Alternative Policy 3 - maintain current level of flood risk management. This policy could also apply as policies maintaining the current level of flood risk management is the same as ‘do nothing’ in this considered case. But it does imply that a certain level of flood risk management is being carried out which is not correct.

Policy 4 - maintain the current level of flood risk into the future. As with policy 3, this policy could apply, but it implies a level of activity that is not happening.

Policy 5 - reduce the level of flood risk, both now and in the future. This policy is not justified by the level of flood risk within the policy unit. There is uncertainty about how effectively changes in land management and vegetation cover will alter run-off at the catchment scale. It is known to work locally, but we do not yet know its effect on the catchment as a whole. Uncertainties

and Changes in land management will depend on the agreement of landowners. dependencies

The understanding of the impact of climate change on groundwater is still in its infancy, and there is still a lot of uncertainly surrounding the impact on groundwater flooding events.

Environment Agency River Adur CFMP - Appendix B (September 2008) 121 Form B9 Requirements for further policy development and appraisal Policy unit 4 – South Downs (West) Is there a need for further policy development? No If yes, then mark policy options for more detailed development. Some complex policies may require more detailed development, probably at Strategy Plan level. Is there a need for further more detailed appraisal? No If yes, take forward to strategy study.

Environment Agency River Adur CFMP - Appendix B (September 2008) 122

Form B10 Indicators for monitoring, review and evaluation This form sets out the indicators that need to be included in the policy implementation plan, for policy monitoring, drawing on the residual risks and likely impacts identified above. This will allow better review and evaluation of the policy when implemented. Policy unit 4 – South Downs (West) Indicators to be included in policy unit 4 implementation plan are:

Social - Number of people affected by the 1% annual probability flood event downstream in policy units 5 (Worthing) and 7 (Shoreham and Adur Estuary). - The estimated number of properties affected by Downland ‘muddy’ surface water flooding downstream in policy unit 5 (Worthing).

Environmental - Landscape character assessment of the AONB, ESA and proposed National Park.

Environment Agency River Adur CFMP - Appendix B (September 2008) 123

Policy unit 5 Worthing Policy appraisal forms Form B5 – Summary of current and future levels of and responses to flood risk. Form B6 – Appraisal of policy options against policy unit objectives. Form B7 – Summary of losses and gains. Form B8 – Summary of preferred policy. Form B9 – Requirements for further policy development and appraisal. Form B10 – Indicators for monitoring, review and evaluation.

Environment Agency River Adur CFMP - Appendix B (September 2008) 124

Form B5 Summary of current and future levels or and responses to flood risk Policy unit 5 - Worthing Defences: There is 6.5km of culverted channel on the Ferring Rife and Teville Stream in this policy unit

Flood warning: This policy unit is covered by the Lower Ferring Rife at south Ferring the Upper Ferring Rife at north Ferring Flood Warning Areas. The Teville Stream is not covered by a Flood Warning Area. There are over 210 properties Current responses to flood risk in this policy unit connected to the flood warnings direct service. within the policy unit Maintenance: The flapped outfalls to the sea on the Ferring Rife and Teville Stream are maintained. We carry out river channel maintenance, culvert clearance and maintenance of key surface water storage areas, such as Brooklands Lake. There are also coastal defences in this policy unit. The estimated cost of maintaining the channels and existing defences under the Environment Agency’s responsibility is approximately £90,000. Standards of service that apply Standard of protection: Standard of protection offered by the storage pond, to flood defences within the Brooklands Lake, is unknown. policy unit In 10% flood In 1% flood In 0.1% flood Receptors outline* outline* outline* Residential properties 2 52 502 Commercial properties 0 0 23 Population 5 124 1200 Property damages £66,950 £1.646 million N/A Agricultural damages £1,565 £1,565 N/A A roads 0.09 km 0.09 km 1.17 km Railways 0.002 km 0.08 km 0.7 km Agricultural land Grade 1 0.01 km2 0.01 km2 0.26 km2 Agricultural land Grade 2 0.002 km2 0.002 km2 0.22 km2 What is currently exposed to Agricultural land Grade 3 0 km2 0 km2 0.06 km2 flooding? Agricultural land Grade 4 0 km2 0 km2 0 km2 Agricultural land Grade 5 0 km2 0 km2 0 km2 SNCIs 0.04 km2 0.04 km2 0.13 km2 SSSI 0 km2 0 km2 0 km2 Listed Buildings 0 1 1 SM 0 0 0 AONB 0km2 0.02 km2 0.04 km2 ESA 0 km2 0 km2 0.04 km2 Registered Historic Parks 2 2 2 and Gardens 0 km 0 km 0 km Proposed National Park 0 km2 0 km2 0.04 km2 * 10% and 1% based on broadscale model results and 0.1% based on Flood Zone 2 Economic and social receptors: There is a flood risk to people, properties and infrastructure from fluvial flooding, surface water flooding and groundwater flooding in the urban areas of this policy unit.

Currently approximately 50 properties within the Ferring area are at risk of fluvial flooding from the Ferring Rife, from the 1% annual probability fluvial flood event.

A short length of the A2032 and A259 to the north west of Worthing and the Who and what are currently railway line in the north of Ferring are at risk of flooding for the 1% annual most vulnerable to flood probability flood event. The A27 was closed for a period of time due to damage and losses? groundwater flooding during the 2000 flood event.

A very small area of agricultural land (grades 1 and 2, excellent and very good) is at risk of flooding for the 1% annual probability flood event.

Environmental designations: There are no internationally or nationally designated sites or SSSIs at risk of flooding for the 1% annual probability flood event within this policy unit.

Environment Agency River Adur CFMP - Appendix B (September 2008) 125 Approximately 0.04km2 of the Ferring SNCI is located within the 1% annual probability flood event outline in this policy unit. The sensitivity of this site to flooding is low.

Landscape: The Sussex Downs AONB, South Downs ESA and proposed National Park are within this policy unit, however, only a small portion of the AONB and none of the ESA or proposed National Park are located within the 1% annual probability flood event outline; less than 0.05km2 is within the 0.1% annual probability flood event outline.

Natural and Historic Environment: There is one listed building located within the 1% annual probability flood outline. There is no extent of registered historic parks and gardens and no SMs at risk of flooding for any of the considered annual probability flood events. Sea level rise and increased storminess as a result of climate change*.

*To represent future sea level rise, the tidal boundary within the broadscale model was scaled to What are the key factors that increase the maximum still water level by 600mm for the 100 year timescale. These climate change could drive future flood risk? figures used were the accepted approach for ‘typical’ catchments when the scoping stage broadscale modelling was carried out. Since the scoping stage was completed new Defra guidance (October 2006) on climate change has been released which suggest that for a 100 year time scale, sea level may rise by almost 1m. Therefore the results from the broadscale model in the tidally influenced areas are likely to have under predicted the increase in flood risk and damages in the future. There is a small increase (approximately £0.04 million) in AAD due to climate change over the next 100 years.

What are the possible future In 100 years approximately 60 properties are at risk of flooding from the Ferring levels of flood risk under the Rife from the 1% annual probability fluvial flood event. main scenarios?

Surface water flooding incidents are also likely to increase in frequency and severity due to climate change (increased rainfall). What potential responses (or There is potential to reduce flood risk through changes in land use by reducing groups of responses) are run-off in the catchment. There is potential to limit increased run-off from new being considered to manage development by installation of SuDS. And also the prevention of vulnerable flood risk? development in flood risk areas. We have estimated the future increase in flood risk within this policy unit on the best available prediction we have of climate change, frequency and size of storms and flood events in the future.

The understanding of the impact of climate change on groundwater is still in its infancy, and there is still a lot of uncertainly surrounding the impact on What gaps and uncertainties groundwater flooding events. are there in knowledge, and what assumptions have been Delivering this policy will partly depend on developing and implementing an made? effective urban drainage strategy in partnership with the local drainage authority, highway department, water and sewerage company and other relevant authorities or responsible parties.

Flood risk from the sea is also a significant consideration in this policy unit. Therefore, fluvial flood risk management options must fit with shoreline management plan policy and actions.

Environment Agency River Adur CFMP - Appendix B (September 2008) 126 Generic response: Rural land use change – changing farming practices to reduce run-off rates 1% annual probability fluvial flood Results from broadscale modelling damages (£m)

Change in land use has been applied to the upper parts of this Ferring Rife Future basecase = £1.835 catchment within the broadscale model. The results show a small reduction in Generic response = £1.617 flood damages within this policy unit of approximately 12%. % change = -12% Conclusions Although the impact of flood risk from changing land use in the upper catchment is not large, it is nonetheless significant. Together with other downstream measures, land use change in the upper catchment can provide a useful way of reducing flood risk in this policy unit.

Generic response: Attenuation/retention (storage) on the Ferring Rife 1% annual probability fluvial flood Results from broadscale modelling damages (£m) The broadscale modelling has indicated that applying flood storage in the upper catchment of the Ferring Rife (of no specific size or location) has a Future basecase = £1.835 negative effect on flood damages within this policy unit (approximately £0.443 Generic response = £2.278 million increase in flood damages). The results show a 24% increase in flood damages for the 1% annual probability fluvial flood event. % change = +24% Conclusions A large flood storage reservoir on the upper parts of the Ferring Rife catchment will provide little benefit to Ferring. The Ferring Rife is affected by tide locking at the bottom end of the catchment and therefore flood damages would be reduced if additional storage for flood water was made available within Ferring itself.

Environment Agency River Adur CFMP - Appendix B (September 2008) 127 Form B6 Appraisal of policy options against policy unit objectives Policy unit 5 – Worthing KEY = Scale of policy impact on objective: Not appraised Baseline Meets objective No impact Doesn’t meet object Uncertain The preferred policy option is indicated below by the policy option highlighted in pink Baseline (current Policy 1 Policy 2 Policy 3 Policy 4 Policy 5 Policy 6 and future) No maintenance of watercourses. Channels become Significant Reduction in blocked with improvement in the maintenance of vegetation and level of channel watercourses. Improved level of conveyance is maintenance of Channels become Maintenance of the channel maintenance reduced. watercourses. blocked with vegetation channels continues. of watercourses.

and conveyance is Significant localised The flood warning Some localised There is potential to reduced. The flood warning protection measures Current and future service is withdrawn. protection measures increase water service remains in introduced. baseline with current introduced. retention by The flood warning place. The flood warning flood risk No maintenance The flood warning introducing flood service remains in service is improved. management. undertaken on service is improved. storage areas along place. Maintenance of the surface water and the Ferring Rife. surface water and Upgrade of surface urban drainage Improvements to the Reduced level of urban drainage water and urban networks. surface water and maintenance of the networks continue. drainage networks to urban drainage surface water and increase capacity and A do nothing networks. urban drainage meet design approach would networks. standards for the increase the flooding future. Catchment Targets and Opportunities and in an unmanaged and objectives Indicators Constraints unpredictable way. Economic objectives Ensure flood damages Targets Opportunities The results of - Provide development control do not significantly No significant increase advice to ensure no increase broadscale modelling increase in Worthing due in damages in Worthing in run-off from the new has indicated that to future change (urban from fluvial, surface development proposed in the applying flood storage development and water and urban South East Plan (e.g. in the upper Worthing). climate change). drainage flooding due to - Reduce flood risk and catchment of the future changes (urban improve water quality by The current total Ferring Rife (of no development and promoting and encourage the annual average specific size or climate change). use of SuDS in the proposed damages from fluvial No maintenance of Significant location) has a urban developments in As channels and flooding and estimated channels and Improved channel improvements in negative effect on Worthing. drainage networks The total annual Indicators Constraints damages resulting drainage networks maintenance, drainage channel flood damages within decrease in capacity average damages Total annual average - Government and international from surface water would lead to a networks and localised maintenance, this policy unit with a legislation, environmental and condition due to from fluvial flooding damages (to properties flooding are significant increase in protection measures localised protection 24% increase in flood management policies, plans reduced maintenance and estimated and agriculture) from and strategies for the approximately £70,000 flooding with total will mitigate the affects measures and damages for the 1% the total annual damages resulting fluvial flooding (£AAD). catchment must be complied and around £4,000 annual average of climate change. The upgrading of the annual probability average damages from from surface water with, such as accommodating respectively. damages from fluvial total annual average drainage network fluvial flood event. new housing within the fluvial flooding and flooding will increase Estimated* damages flooding and damages from fluvial would reduce total catchment as detailed by the estimated damages slightly over time due resulting from surface South East Plan and This increases to estimated damages flooding and estimated annual average Therefore annual resulting from surface to the affects of water and groundwater compliance with the Habitats around £108,000 for resulting from surface damages resulting from damages from fluvial average damages are Directive. water flooding will climate change to be flooding (£). total annual average water flooding being surface water flooding flooding and the likely to be more than - Steep catchments of the increase to be more around £108,000 and damages from fluvial significantly more will remain are estimated damages £70,000 and the South Downs result in rapid than £145,000 and more than £5,000 *Estimation based on historical run-off and quick responses flooding and more than £180,000 and approximately £70,000 resulting from surface estimated damages more than £7,000 respectively. damages observed in the to rainfall events. than £5,000 for more than £10,000 and £4,000. water flooding to be resulting from surface Brighton area from the 2000/ respectively. 2001 flood event (Binnie Black estimated surface respectively. minimal. water flooding may & Veatch 2001 – Flood Defence water damages in the also remain around Assessment of Downland future. £4,000. Flooding).

However damages may decrease if additional storage is provided within the Ferring Rife.

Environment Agency River Adur CFMP - Appendix B (September 2008) 128 Ensure that river Targets Opportunities The level of channel - Improvements in the channel and flood Maintain a suitable efficiency of channel and and flood defence defence maintenance balance of annual river The current annual Channel and flood maintenance flood defence maintenance The level of channel expenditure is channel and flood processes. channel and flood defence maintenance The level of f channel expenditure is likely to No channel and flood and flood defence appropriate to the defence maintenance - Effective and efficient use of defence maintenance expenditure remains and flood defence be slightly less than developer contributions for defence maintenance maintenance property economic expenditure (£) to expenditure is Channel and flood at approximately maintenance £90,000, however, the flood risk management. expenditure is expenditure will damage in urban areas annual average - To work with Defra and approximately defence maintenance £90,000. Annual expenditure will broadscale modelling incurred as no increase to be from flooding. damages from fluvial farmers to produce soil £90,000; the annual expenditure reduces to average damages increase over time to has indicated that by maintenance is significantly more flooding to property (£). management plans which average damages be less than £75,000. from fluvial flooding to mitigate the affects of applying flood storage have a benefit to flood risk undertaken. Annual than £90,000. from fluvial flooding to Annual average property increase over climate change to in the upper through reducing the run-off average damages Annual average Indicators rate. property are currently damages from fluvial time due to the affects slightly more than catchment of the from fluvial flooding damages from fluvial Balance of annual river Constraints around £69,800, flooding to property are of climate change to £90,000. Annual Ferring Rife there will - Available funding for the to property increase flooding to property channel and flood increasing to around likely to be more than be around £107,900. average damages from be an increase in flood initial set up of new flood risk to be more than are estimated to be defence maintenance management schemes. £107,900 in the future. £145,000. fluvial flooding to damages to more than £180,000. less than £8,000. expenditure (£) to - Older flood defence With better property will remain £70,000.

annual average structures are likely to be The current balance of The balance of maintenance around £69,800. more costly to maintain. The balance of The balance of damages from fluvial - expenditure to expenditure to efficiency and However, this may not Limited available information expenditure to expenditure to flooding to property (£). on surface water and damages is damages is effective use of The balance of be the case if storage damages is damages will be groundwater flood damages. considered unacceptable. funding the balance of expenditure to was provided within unacceptable. unacceptable with acceptable. expenditure to damages will remain the Ferring Rife. expenditure being damages will remain acceptable. unjustifiably high. acceptable. The balance of expenditure to damages is uncertain. Social objectives Opportunities - Provide development control advice to ensure no increase in run-off from the new No maintenance of development proposed in the Approximately 124 channels and South East Plan (e.g. people and 52 drainage networks Reduction in Worthing). properties are at risk and a reduction in the maintenance of - Reduce flood risk and of localised fluvial height of channels and drainage Maintenance of Targets improve water quality by The results of promoting and encourage the flooding by the current embankments would networks would result channels and Improved channel No significant increase broadscale modelling in the number of people use of SuDS in the proposed 1% annual probability result in a significant in an increase in the drainage networks maintenance, drainage urban developments in has indicated that flood event. This increase in the frequency, extent and continues at the networks and localised Improved channel or properties affected by Worthing. applying flood storage - increases slightly to frequency, extent and depth of localised current level. protection measures maintenance and the 1% annual Investigate the feasibility of in the upper incorporating the Teville around 140 people depth of localised fluvial and surface and will mitigate the affects increased local probability fluvial flood catchment of the Stream into the Floodline and 59 properties in fluvial and surface urban drainage The number of people of climate change. The defence works and event or surface water Warnings Direct service by Ferring Rife (of no the future. water and urban flooding. and properties at risk number of people and flood warning service flooding in Worthing in installing new level gauges specific size or on the Teville stream. drainage flooding. of localised fluvial properties affected by will reduce the the future. location) has a - Continued practice and There are some It is likely that the flooding is likely to localised fluvial number of people negative effect within development of the historic records of The number of number of people and slightly increase to flooding will remain at affected by localised Indicators Emergency Response Plan in the catchment. surface water flooding people and properties properties at risk of approximately 140 approximately 124 and fluvial flooding to less Ensure the impact of Number of people and Brighton and Hove, Worthing, However, this may not properties affected by Shoreham, and Burgess Hill. in this area but they at risk of localise localise fluvial flooding and 59 respectively. 52 respectively. than 15 and number flooding on people and - be the case if storage the 1% annual Influence the coastal defence are limited and we fluvial flooding will will increase to be of properties affected property does not strategy, along the Lower was provided within have not been able to increase to be more than 140 and 59 Over time the number The estimated number to less than 5. significantly increase in probability fluvial flood Adur, Teville Stream and the Ferring Rife. Ferring Rife, to improve the estimate the number significantly more respectively. of properties at risk of of properties at risk of Worthing in the future. event. sustainability of flood risk of properties affected than 140 and 59 surface water and surface water and No properties will be management in the this area. It is uncertain how this by surface water respectively. There will be a urban drainage urban drainage will at risk of surface The estimated number Constraints policy option would - flooding from these substantial increase flooding will gradually remain at the current water and urban of properties affected by Government and international influence the number legislation, environmental accounts. There will be a from the current level in increase from the level. drainage flooding. surface water and of people and groundwater flooding. management policies, plans significant increase the number of current level due to and strategies for the properties affected by However, surface from the current level properties affected by the affects of climate Coverage of Flood Flood Warning catchment must be complied the 1% annual with, such as accommodating water flooding is a in the number of surface water and change. Warning Service is Service is improved *Surface water/ groundater probability flood event. flooding estimates based on new housing within the known problem in this properties affected by urban drainage increased, system is in terms of accuracy catchment as detailed by the historical records. area and it is likely to surface water and flooding. The current level of improved in terms of and coverage South East Plan and Flood Warning increase in the future. urban drainage Flood Warning accuracy and compliance with the Habitats Service is retained at Coverage of Flood Directive. flooding. Service remains in coverage. - the current level Warning Service Visual impact of flood risk An estimated 272 The current level of place. management activities within the proposed National Park properties are Withdrawing the flood Flood Warning Service or Areas of Outstanding currently covered by a warning system may remains in place. Natural Beauty. flood warning service. result in increased - CFMP objectives and policies must complement those of risk to human life. the SMP that affect the CFMP area.

Environment Agency River Adur CFMP - Appendix B (September 2008) 129 Targets Opportunities - Provide development control Currently No increase in flooding No maintenance of advice to ensure no increase approximately 0.09km of A roads and railway in run-off from the new channels and of A road and 0.08km line or increase in extent development proposed in the drainage networks Reduction in South East Plan (e.g. of railway, but no Maintenance of of critical infrastructure would result in an maintenance of Worthing). critical infrastructure channels and flooded, in Worthing and increase in the channels and drainage Constraints sites are affected by drainage networks surrounding areas, from - Steep catchments of the frequency, extent and networks would result Improved channel the 1% annual continues at the The results of a 1% annual probability South Downs result in rapid depth of localised in an increase in the maintenance, drainage run-off and quick responses probability flood event. current level. broadscale modelling fluvial flood event or fluvial and surface frequency, extent and networks and localised to rainfall events. The extent of road and has indicated that surface water flooding. - Transport links in the and urban drainage depth of localised protection measures railway affected by the Approximately 1km of Improved channel applying flood storage catchment are a vital part of flooding. fluvial and surface and will mitigate the affects the communication network 1% annual probability A road and 0.5km of maintenance, in the upper Indicators urban drainage of climate change. regionally, nationally and fluvial flood event is railway are affected by increased local catchment of the Length of A road and Significantly more flooding. internationally, in particular expected to increase flooding during the 1% defence works and Ferring Rife (of no railway line (km) affected the railways connecting than 1km of A road Approximately 0.09km in the future to more annual probability upgrading of the specific size or by the 1% annual London to the south coast and 0.5km of railway More than 1km of A of A road and 0.08km and connecting the coastal than 1km and 0.5km flood event. No drainage network will location) has a probability fluvial flood are likely to be at risk road and 0.5km of of railway but no critical Ensure the disruption towns and cities, the A23, respectively. No critical infrastructure reduce fluvial and negative effect within event. A24, A27, A259, A283 and of flooding from railway are likely to be infrastructure sites are caused by flooding to critical infrastructure sites are at risk of surface water and the catchment. A2032. fluvial flooding during at risk of flooding from affected by flooding transport and critical - Visual impact of flood risk sites are at risk in the fluvial flooding from urban drainage However, this may not Number of critical the 1% annual fluvial flooding during during the 1% annual infrastructure does not management activities within future. the 1% annual flooding. be the case if storage infrastructure sites probability flood the 1% annual probability flood event. increase in Worthing in the proposed National Park probability flood event. was provided within affected by the 1% or Areas of outstanding event. probability flood event. the future. There are historic No extent of A road, the Ferring Rife. annual probability fluvial Natural Beauty. No critical No critical There will be no - CFMP objectives and policies records of closure and There is likely to be a railway or critical flood event. infrastructure sites infrastructure sites are change from the must complement those of disruption of A road gradual increase in infrastructure sites It is uncertain how this the Shoreline Management are at risk of fluvial at risk of fluvial flooding current extent of (A24 and A 27)/ rail extent and/ or will be affected by policy option would Number and period of Plan (SMP) that affects the flooding from the 1% from the 1% annual surface water and CFMP area. links and one hospital frequency from the fluvial or surface affect the extent of recorded A road and annual probability probability flood event. urban drainage being affected by current level of A water and urban fluvial, surface water railway closures due to flood event. flooding with some surface water and roads, railway and drainage flooding. and urban drainage surface water flooding*. More surface water disruption from closure urban drainage critical infrastructure at flooding to A roads, Significantly more and urban drainage of road and rail links flooding. risk of surface water railways and critical Number of critical surface water and flooding (extent and/ or and one hospital being and urban drainage infrastructure sites. infrastructure sites urban drainage frequency) of A roads, affected. Surface water and flooding due to the recorded as being flooding (extent and/ railway and critical urban drainage affects of climate affected by surface or frequency) of A infrastructure sites will flooding is a known change. water flooding*. roads, railway and occur. problem in this area critical infrastructure and it is likely to *Surface water/ groundwater sites will occur. flooding estimates based on increase in the future. historical records. Opportunities - Targets Reduce surface water run-off There are no definitive and soil erosion by Reduction in the number supporting the existing and historic records of of properties affected by future management policies ‘muddy’ surface water There will be a muddy flooding in regarding environmentally flooding for this policy sensitive farming practices. gradual increase in The impact of ‘muddy’ northern parts of unit and therefore we The impacts of - Support the existing flood the impact of ‘muddy’ flooding will remain at Worthing, including have not been able to ‘muddy’ flooding will The impacts of ‘muddy’ With increased The provision of flood Reduce the impact of defence measures in relation flooding due to the the current level as Findon. to surface water flooding. estimate the number significantly increase flooding will increase maintenance and storage associated muddy flooding in affects of climate improvements in Constraints of properties affected with a significant with a decrease in local defence works with the Ferring Rife is northern parts of - Steep catchments of the change. Flooding is maintenance and Indicators or the impacts from number of additional maintenance of there are no incidents not likely to have any Worthing, including South Downs result in rapid likely to occur more localised protection The estimated number run-off and quick responses this type of flooding. properties being watercourses and or associated impacts affect on the impacts Findon. frequently, to a greater measures mitigate the of properties affected by to rainfall events. affected by this type drainage networks. of ‘muddy’ flooding. of ‘muddy’ flooding. - A suitable level of productivity depth, and additional affects of climate Downland ‘muddy’ However, ‘muddy’ of flooding. from agricultural land needs properties may be change. surface water flooding. flooding is a known to be retained. affected. - Visual impact of flood risk problem in this area * Estimates of properties management activities within and it is likely to affected by muddy flooding the proposed National Park based on historical records. or Areas of Outstanding increase in the future. Natural Beauty. Environmental objectives Targets Opportunities There is currently Doing nothing and Reducing the There would be a The extent of the SNCI Improved channel Increasing the flood - Help meet national 2 Protect and enhance the biodiversity action plan (BAP) 0.04km of the Ferring with a reduction in maintenance of the slight increase to within the 1% annual maintenance, storage areas in this Ferring Rife and Rife and Meadows the height of the channels would approximately 0.1km2 probability flood event increased local policy unit would Protect and enhance the targets. Meadows Site of Nature Constraints SNCI located within embankments the eventually allow the in the area of the outline will remain at defence works and increase the potential Ferring Rife and - Conservation Some environmentally the 1% annual Ferring Rife would Ferring Rife to flood SNCI within the 1% approximately 0.04km2. upgrading of the to increase the area of Meadows Site of Nature designated habitats are Importance. susceptible to changes in probability flood event flood more frequently more frequently, with annual probability drainage network is SNCI to more than Conservation 2 flood frequency, floodwater outline. and to increased an increase in flood flood event outline due There will be no likely to reduce the 0.5km and improve or Importance. Indicators chemistry, groundwater flood depths. The depths, increasing the to the affects of notable change in the extent of flooding and increase the habitat levels and drainage system Habitat quality and maintenance. This is likely to area of the SNCI area of the SNCI within climate change. habitat and species therefore the extent types and species species diversity. - Changes to flood risk increase to around within the 1% annual the 1% annual diversity within the of the SNCI within the diversity in a managed

Environment Agency River Adur CFMP - Appendix B (September 2008) 130 management can affect the 0.1km2 in the future, probability flood probability flood outline There is likely to be a SNCI. 1% annual probability and controlled way. landscape, its character and with a small increase outline increases to to more than 0.1km2. small increase in flood outline to less value as an amenity. 2 - CFMP objectives and policies in habitat and species significantly more habitat and species than 0.04km . 2 must complement those of diversity. than 0.1km . There is increased diversity. the Shoreline Management potential to improve or Decrease in flooding Plan (SMP) that affects the CFMP area. There is increased increase the habitat extent (duration and potential to types and species depth) is likely to significantly improve diversity within the have a negative or increase the SNCI. However, this affect on the habitat habitat types and would occur in an types and species species diversity unmanaged way. diversity within the within the SNCI. SNCI. However, this would occur in an unmanaged and uncontrolled way. Does this policy change flood risk locally or elsewhere: Unlikely to affect Unlikely to affect Unlikely to affect Unlikely to affect Unlikely to affect Unlikely to affect adjacent policy adjacent policy adjacent policy units adjacent policy units adjacent policy units adjacent policy units units units

Environment Agency River Adur CFMP - Appendix B (September 2008) 131 Form B7 – Summary of losses and gains.

Policy unit Policy Unit 5 - Worthing name/number:

Preferred policy Policy options Losses Gains option relative to current baseline Policy option P1 Environmental NO LOSSES HIGH+ Not preferred option – There are limited gains The area of the under this policy option. Ferring Rife and The numbers of people Meadows SNCI will and properties significantly increase adversely affected by by significantly more 2 removing FRM are than 0.96km but in an unacceptably high. The unmanaged and AAD and level of uncontrolled way disruption caused by

flooding are also high Social HIGH- NEUTRAL= and the environmental The number of people The number of critical effects are and properties at risk of infrastructure at risk unpredictable due to the

localised fluvial flooding from a 1% AEP flood unmanaged and in a 1% AEP flood event event will remain at 0 uncontrolled nature of will increase by this policy option.

significantly more than

16 and 7 respectively The number of

properties at risk of

surface water and urban drainage flooding will

increase significantly

Withdrawing the flood warning system will

increase risk to human

life The lengths of A road

and railway at risk from

a 1% AEP flood event will increase by

significantly more than

0.91km and 0.42km respectively

Significantly more

surface water and urban drainage flooding to

transport routes will

occur The impact of ‘muddy’

flooding will increase

significantly

Economic HIGH- NO GAINS

The AAD to properties and agricultural land

Environment Agency River Adur CFMP - Appendix B (September 2008) 132 caused by fluvial flooding will increase by significantly more than £110,000 AAD to properties and agricultural land caused by surface water flooding will increase by significantly more than £6,000 The balance of FRM expenditure to AAD is unacceptable with AAD to properties and agricultural land increasing by more than £110,200 Policy option P2 Environmental NO LOSSES HIGH+ Not preferred option – There are limited gains The area of the under this policy option. Ferring Rife and The numbers of people Meadows SNCI will and properties significantly increase 2 adversely affected by by more than 0.96km removing FRM are but in an unmanaged unacceptably high. The way AAD and level of

disruption caused by

flooding are also high Social HIGH- NEUTRAL= and the environmental The number of people The number of critical effects are and properties at risk of infrastructure at risk unpredictable due to the

localised fluvial flooding from a 1% AEP flood unmanaged and in a 1% AEP flood event event will remain at 0 uncontrolled nature of will increase by more this policy option.

than 16 and 7

respectively The number of

properties at risk of

surface water and urban drainage flooding will

increase substantially

The lengths of A road and railway at risk from

a 1% AEP flood event

will increase by more than 0.91km and 0.42km

respectively

Substantially more surface water and urban

drainage flooding to

transport routes will occur

The impact of ‘muddy’

flooding will increase substantially

HIGH- NO GAINS Economic

Environment Agency River Adur CFMP - Appendix B (September 2008) 133 The AAD to properties and agricultural land caused by fluvial flooding will increase by more than £75,000 AAD to properties and agricultural land caused by surface water flooding will increase by more than £3,000 The balance of FRM expenditure to AAD is unacceptable with AAD to properties and agricultural land increasing by more than £75,200 Policy option P3 Environmental NO LOSSES MEDIUM+ Preferred Policy Option – Although there are The area of the some losses in terms of Ferring Rife and the numbers if people Meadows SNCI will and properties and the increase by 2 level of disruption and approximately 0.96km AAD caused by with a small increase flooding, the overall in habitat and species strategy for this CFMP diversity is to increase flood

storage upstream and Social MEDIUM- NEUTRAL= thereby mitigate against The number of people The number of critical future increases in flood and properties at risk of infrastructure at risk risk due to climate

localised fluvial flooding from a 1% AEP flood change. in a 1% AEP flood event event will remain at 0 will increase by

approximately 16 and 7

respectively The number of

properties at risk of

surface water and urban drainage flooding will

increase slightly

The lengths of A road and railway at risk from

a 1% AEP flood event

will increase by approximately 0.91km

and 0.42km respectively

More surface water and urban drainage flooding

to transport routes will

occur in the future The impact of ‘muddy’

flooding will increase in

the future

LOW+ Economic MEDIUM- The balance of FRM The AAD to properties expenditure to AAD Environment Agency River Adur CFMP - Appendix B (September 2008) 134 and agricultural land will remain acceptable caused by fluvial with AAD to properties flooding will increase by and agricultural land approximately £38,000 increasing slightly in AAD to properties and the future agricultural land caused by surface water flooding will increase by approximately £1,000 Policy option P4 Environmental NO LOSSES LOW+ Not preferred option – Although there are The area of the additional benefits in Ferring Rife and terms of the numbers of Meadows SNCI will people and properties not increase in the and reducing the level of future with no notable disruption and AAD change in habitat and caused by flooding, the species diversity overall strategy for this

CFMP is to increase

flood storage upstream Social NO LOSSES HIGH+ and thereby mitigate The number of people against future increases and properties at risk in flood risk due to

of localised fluvial climate change. It flooding in a 1% AEP should therefore be flood event will not unnecessary to further

increase in the future increase FRM in this The number of policy unit in order to properties at risk of ensure risk does not

surface water and increase. urban drainage flooding will not

increase in the future The lengths of A road and railway at risk

from a 1% AEP flood event will not increase in the future

Surface water and urban drainage flooding to transport

routes will not increase in the future

LOW+

The impact of ‘muddy’

flooding will remain at current levels

NEUTRAL=

The number of critical

infrastructure at risk from a 1% AEP flood event will remain at 0

Environment Agency River Adur CFMP - Appendix B (September 2008) 135 Economic NO LOSSES HIGH+

The AAD to properties and agricultural land caused by fluvial flooding will not increase in the future AAD to properties and agricultural land caused by surface water flooding will not increase in the future The balance of FRM expenditure to AAD will remain acceptable with slight increases in FRM expenditure to maintain AAD to properties and agricultural land at current levels in the future Policy option P5 Environmental MEDIUM- NO GAINS Not preferred option – Although there are The area of the Ferring significant gains in Rife and Meadows SNCI terms of reducing the will be reduced with a numbers of people and possible decline in properties affected by habitat and species flooding, the costs of diversity implementing increased

FRM now and in the Social NO LOSSES HIGH+ future are considered unacceptable. There are The number of people also losses to the and properties at risk environment. of localised fluvial flooding in a 1% AEP flood event will be

reduced by more than 109 and 47 respectively

The number of properties at risk of surface water and

urban drainage flooding will be reduced to 0

The lengths of A road and railway at risk from a 1% AEP flood

event will be reduced Surface water and urban drainage

flooding to transport routes will be reduced The impact of ‘muddy’

flooding will be minimised as far as possible

Environment Agency River Adur CFMP - Appendix B (September 2008) 136

NEUTRAL=

The number of critical infrastructure at risk

from a 1% AEP flood event will remain at 0

Economic HIGH-

The balance of FRM HIGH+ expenditure to AAD is The AAD to properties unacceptable with and agricultural land significant increases in caused by fluvial FRM expenditure to flooding will be reduce AAD to reduced properties and AAD to properties and agricultural land agricultural land caused by surface water flooding will be minimal Policy option P6 Environmental NO LOSSES MEDIUM+ Not preferred option – Although there are The area of the moderate gains in terms Ferring Rife and of the environment and Meadows SNCI will AAD to properties and increase by more than 2 agricultural land, there 0.46km but in a are also losses managed and associated with the controlled way numbers of people and

properties affected by

flooding and the balance Social LOW- NEUTRAL= of expenditure. In The number of people The number of critical addition to this, the and properties at risk of infrastructure at risk effects listed here are

localised fluvial flooding from a 1% AEP flood relatively uncertain. in a 1% AEP flood event event will remain at 0 are likely to be increased Flood storage is not

The number of likely to have any properties at risk of effect on ‘muddy’ surface water and urban

drainage flooding is

uncertain The lengths of A road

and railway at risk from

a 1% AEP flood event are uncertain

The extents of surface

water and urban drainage flooding to

transport routes are

uncertain LOW- MEDIUM+ Economic The AAD to properties AAD to properties and and agricultural land agricultural land caused by fluvial caused by surface flooding are likely to water flooding will not increase increase in the future The balance of FRM and may be reduced Environment Agency River Adur CFMP - Appendix B (September 2008) 137 expenditure to AAD is uncertain with reductions in FRM expenditure and likely increases in AAD to properties and agricultural land

Key HIGH: High negative A policy has a ‘high negative’ effect where it could contribute to a social, economic or environmental objective in a significantly negative way. A ‘high negative’ effect could be: (i) a very large increase in current flood risk; (ii) very large projected increases in flood risk under future conditions, and/or; (iii) significant additional social, economic and/or environmental losses. MEDIUM: Medium negative A policy has a ‘medium negative’ effect where it could contribute to a social, economic or environmental objective in a negative way. A ‘medium negative’ effect could be: (i) an increase in current flood risk; (ii) a projected increase in flood risk under future conditions, and/or; (iii) social, economic and/or environmental losses. LOW: Low negative A policy has a ‘low negative’ effect where it could make a limited contribution to a social, economic or environment objective, but where the overall contribution would be negative. A ‘low negative’ effect could be: (i) an overall increase in current flood risk; (ii) an overall increase in flood risk under future conditions, and/or; (iii) overall social, economic and/or environmental losses. NEUTRAL: Neutral A policy has a ‘neutral’ effect where it makes neither a positive or negative contribution to a social, economic or environmental objective. A ‘neutral’ effect could be: (i) no change in current level of risk. In this instance the current level of risk would have to be low, so that the residual risk after a neutral policy was implemented remained acceptable; (ii) no change in flood risk under future conditions. In this instance projected future risk would need to be low so that the residual risk after a neutral policy was implemented remained acceptable, and/or; (iii) no additional social, economic and/or environmental gains or losses. Policy options may also be ‘neutral’ where they are not relevant in a particular policy unit, or where it is not feasible for a policy option to contribute to an objective. HIGH: High positive A policy has a ‘high positive’ effect where it could contribute to a social, economic or environmental objective in a significantly positive way. A ‘high positive’ effect could be: (i) a very large reduction in current flood risk; (ii) avoiding/reducing very large projected increases in flood risk under future conditions, and/or; (iii) significant additional social, economic and/or environmental gains. MEDIUM: Medium positive A policy has a ‘medium positive’ effect where it could contribute to a social, economic or environmental objective in a positive way. A ‘medium positive’ effect could be: (i) a reduction in current flood risk;

Environment Agency River Adur CFMP - Appendix B (September 2008) 138 (ii) avoiding/reducing projected increases in flood risk under future conditions, and/or; (iii) additional social, economic and/or environmental gains. LOW: Low positive A policy has a ‘low positive’ effect where it could make a limited contribution to a social, economic or environment objective, but where the overall contribution would be positive. A ‘low positive’ effect could be: (i) an overall reduction in current flood risk; (ii) an overall avoidance/reduction in flood risk under future conditions,

Environment Agency River Adur CFMP - Appendix B (September 2008) 139

Form B8 Summary of preferred policy Policy unit 5 - Worthing Physical characteristics: - Largely an urban unit, including Worthing, Lancing and parts of Littlehampton. - Urban centres are separated by the Ferring Rife and Teville Stream floodplains. - Geology mainly comprises Chalk formation, which is dissected by Lambeth Group clays through the centre of the policy unit. - Small pockets of high grade agricultural land (grades 1 and 2) lie just north of Worthing and in Sompting, at the foot of the South Downs. - Low-lying topography across the whole coastal plain region. Flood mechanism - Combination of groundwater, surface water run-off and fluvial flooding from the Ferring Rife. Receptor: - People, properties and infrastructure in the urban areas. The A27, a main transport route, is susceptible to groundwater and surface water flooding. - Currently approximately 52 properties at risk of fluvial flooding in the policy unit from the 1% annual probability fluvial flood event in the Ferring Rife area. - In 100 years approximately 60 properties at risk of flooding in the Ferring Rife area. - There are many more properties at risk from fluvial, surface water and groundwater Problem/risk flooding in Sompting – the exact number is unknown. Current Flood Risk Summary Number of properties at risk of flooding (1% annual probability flood event) 52 Total damages (approx.) (1% annual probability flood event) £1.6 million Annual averages damages (approx.) £70,000 Future Flood risk: - Flood risk in the Ferring Rife area is currently assessed as low to medium, assessment remains unchanged as a result of future scenarios. - We are uncertain of the exact impact of flooding in the Teville Stream area, but it is predicted that a combination of groundwater flooding, surface water run-off and/or fluvial flooding could result in a flood event flooding the low-lying areas of Sompting. It is also predicted that future scenarios will increase this risk, however, the extent to which this increase affects the people, property and environment in the Teville Stream area is unknown. Future Flood Risk Summary (in 100 years time) Number of properties at risk of flooding (1% annual probability flood event) 60 Total damages (approx.) (1% annual probability flood event) £1.835 million Annual averages damages (approx.) £108,000 Policy 3 - Continue with existing or alternative actions to manage flood risk at the current Policy selected level (accepting that flood risk with increase over time from this baseline). This policy is appropriate where the current level of flood risk management is considered appropriate. Current management and maintenance activities include maintaining defences, grass and weed cutting, debris removal and inspections. It is recognised that flood risk will change in the future, and management actions may change in time to gain efficiencies or improve effectiveness. This policy is appropriate for this policy unit for the following reasons: - The current level of flood risk is low to medium and it is not expected to significantly Justification increase in the future. - The current flood risk management activities, carried out for the localised fluvial and surface water and urban drainage flooding problems, are considered appropriate and acceptable for the level of risk. - The selected policy would help achieve the catchment objectives to ensure the impact of flooding does not significantly increase. - Ensure flood damages do not significantly increase in Worthing due to future change (urban development and climate change). - Ensure that river channel and flood defence maintenance expenditure is appropriate to the property economic damage in urban areas from flooding. - Ensure the impact of flooding on people and property does not significantly increase in Catchment Worthing in the future. objectives - Ensure the disruption caused by flooding to transport and critical infrastructure does not increase in Worthing in the future. - Reduce the impact of muddy flooding in northern parts of Worthing, including Findon. - Protect and enhance the Ferring Rife and Meadows Site of Nature Conservation Importance.

Environment Agency River Adur CFMP - Appendix B (September 2008) 140 Opportunities: - Provide development control advice to ensure no increase in run-off from the new development proposed in the South East Plan (e.g. Worthing). - Reduce flood risk and improve water quality by promoting and encourage the use of SuDS in the proposed urban developments in Worthing. - Improvements in the efficiency of channel and flood defence maintenance processes. - Effective and efficient use of developer contributions for flood risk management. - To work with Defra and farmers to produce soil management plans which have a benefit to flood risk through reducing the run-off rate. - Investigate the feasibility of incorporating the Teville Stream into the Floodline Warnings Direct service by installing new level gauges on the Teville stream. - Continued practice and development of the Emergency Response Plan in Brighton and Hove, Worthing, Shoreham, and Burgess Hill. - Influence the coastal defence strategy, along the Lower Adur, Teville Stream and Ferring Rife, to improve the sustainability of flood risk management in this area. - Reduce surface water run-off and soil erosion by supporting the existing and future management policies regarding environmentally sensitive farming practices. - Support the existing flood defence measures in relation to surface water flooding. - Help meet national biodiversity action plan (BAP) targets.

Catchment-wide Constraints: opportunities - Government and international legislation, environmental management policies, plans and and constraints strategies for the catchment must be complied with, such as accommodating new housing within the catchment as detailed by the South East Plan and compliance with the Habitats Directive. - Steep catchments of the South Downs result in rapid run-off and quick responses to rainfall events. - Available funding for the initial set up of new flood risk management schemes. - Older flood defence structures are likely to be more costly to maintain. - Limited available information on surface water and groundwater flood damages. - Visual impact of flood risk management activities within the proposed National Park or Areas of Outstanding Natural Beauty. - CFMP objectives and policies must complement those of the Shoreline Management Plan (SMP) that affects the CFMP area. - Transport links in the catchment are a vital part of the communication network regionally, nationally and internationally, in particular the railways connecting London to the south coast and connecting the coastal towns and cities, the A23, A24, A27, A259, A283 and A2032. - A suitable level of productivity from agricultural land needs to be retained. - Some environmentally designated habitats are susceptible to changes in flood frequency, floodwater chemistry, groundwater levels and drainage system maintenance. - Changes to flood risk management can affect the landscape, its character and value as an amenity. Policy 1 - do nothing. The urban areas of Worthing currently have a low level of risk of fluvial flooding and the risk of flooding from surface water and rivers may increase with climate change. Without continued maintenance the annual average damages would increase to more than £180,000. Do nothing is, therefore, not an appropriate policy.

Policy 2 - reduce current level of flood risk management. As with policy option 1, the annual average damages would increase to more than £145,000 and would become unacceptable in the future under a ‘do less’ policy. Alternative

policies Policy 4 – maintain the current level of flood risk into the future. This policy unit could also considered apply, however, it implies considerable increased flood risk management in the future. The need for this has not been identified or considered justifiable.

Policy 5 - reduce the level of flood risk, both now and in the future. The current level of risk is considered tolerable and therefore this policy is not justified.

Policy 6 - increase flooding to reduce flooding elsewhere. There are no opportunities within this policy unit for this policy. We have estimated the future increase in flood risk within this policy unit on the best available prediction we have of climate change (prior to the Defra October 2006 guidance), frequency Uncertainties and size of storms and flood events in the future. and

dependencies The understanding of the impact of climate change on groundwater is still in its infancy, and there is still a lot of uncertainly surrounding the impact on groundwater flooding events.

Environment Agency River Adur CFMP - Appendix B (September 2008) 141

The extent of fluvial flooding and the potential consequences are uncertain for the Teville Stream. Although broad conclusions may be drawn, the lack of sufficient data to model the watercourse limits the analysis that can be completed in the CFMP. The figures presented in this table for fluvial flooding relate to the Ferring Rife.

Environment Agency River Adur CFMP - Appendix B (September 2008) 142 Form B9 Requirements for further policy development and appraisal Policy unit 5 - Worthing Is there a need for further policy development? No If yes, then mark policy options for more detailed development. Some complex policies may require more detailed development, probably at Strategy Plan level. Is there a need for further more detailed appraisal? No If yes, take forward to strategy study.

Environment Agency River Adur CFMP - Appendix B (September 2008) 143

Form B10 Indicators for monitoring, review and evaluation This form sets out the indicators that need to be included in the policy implementation plan, for policy monitoring, drawing on the residual risks and likely impacts identified above. This will allow better review and evaluation of the policy when implemented. Policy unit 5 – Worthing Indicators to be included in policy unit 5 implementation plan are:

Economic - Total annual average damages (to properties and agriculture) from fluvial flooding (£AAD). - Estimated damages resulting from surface water and groundwater flooding (£) (based on historical damages). - Balance of annual river channel and flood defence maintenance expenditure (£) to annual average damages from fluvial flooding to property (£).

Social - Number of people and properties affected by the 1% annual probability fluvial flood event. - The estimated number of properties affected by surface water and groundwater flooding (based on historical records). - Length of A road and railway line (km) affected by the 1% annual probability fluvial flood event. - Number of critical infrastructure sites affected by the 1% annual probability fluvial flood event. - Number and period of recorded A road and railway closures due to surface water flooding (based on historical records). - Number of critical infrastructure sites recorded as being affected by surface water flooding (based on historical records). - The estimated number of properties affected by Downland ‘muddy’ surface water flooding (based on historical records).

Environmental - Habitat quality and species diversity.

Environment Agency River Adur CFMP - Appendix B (September 2008) 144

Policy unit 6 Brighton and Hove Policy appraisal forms Form B5 – Summary of current and future levels of and responses to flood risk. Form B6 – Appraisal of policy options against policy unit objectives. Form B7 – Summary of losses and gains. Form B8 – Summary of preferred policy. Form B9 – Requirements for further policy development and appraisal. Form B10 – Indicators for monitoring, review and evaluation.

Environment Agency River Adur CFMP - Appendix B (September 2008) 145

Form B5 Summary of current and future levels or and responses to flood risk Policy unit 6 – Brighton and Hove Defences: There are no formal Environment Agency fluvial flood defence schemes in this policy unit. There are sections of informal raised defences owned by Brighton and Hove City Council for surface water management.

Flood warning: This policy unit is not covered by a Flood Warning Area as it Current responses to flood risk does not suffer from fluvial flooding. There are no properties connected to the within the policy unit flood warnings direct service.

Maintenance: Surface water and groundwater events as large as the 2000/ 2001 event trigger significant emergency works, with a total estimated expenditure of around £0.4 million. Standards of service that apply to flood defences within the Standard of protection: There are no flood defence schemes in this policy unit. policy unit In 10% flood In 1% flood In 0.1% flood Receptors outline* outline* outline* Residential properties 0 0 N/A Commercial properties 0 0 N/A Population 0 0 N/A Property damages 0 0 N/A Agricultural damages 0 0 N/A A roads 0 km 0 km 0 km Railways 0 km 0 km 0 km Agricultural land Grade 1 0 km2 0 km2 0 km2 Agricultural land Grade 2 0 km2 0 km2 0 km2 Agricultural land Grade 3 0 km2 0 km2 0 km2 What is currently exposed to 2 2 2 flooding? Agricultural land Grade 4 0 km 0 km 0 km Agricultural land Grade 5 0 km2 0 km2 0 km2 SNCIs 0 km2 0 km2 0 km2 SSSI 0 km2 0 km2 0 km2 Listed Buildings 0 0 0** SM 0 0 0 AONB 0 km2 0 km2 0 km2 ESA 0 km2 0 km2 0 km2 Registered Historic Parks 2 2 2 and Gardens 0 km 0 km 0 km Proposed National Park 0 km2 0 km2 0 km2 * 10% and 1% based on broadscale model results and 0.1% based on Flood Zone 2 **Several listed buildings are at risk from tidal flooding based on Flood Zone 2 Economic and social receptors: Currently there are no properties or people at risk of fluvial flooding in Brighton and Hove from the 10%, 1% or 0.1% annual probability flood event.

No extent of A road, railway line or graded agricultural land lies within any of the considered annual probability flood event outlines.

Tourist infrastructure and amenities are not at risk of flooding from the 10%, 1% or 0.1% annual probability flood events.

Who and what are currently Environmental designations: most vulnerable to flood There are no internationally or nationally designated sites, SSSIs or SNCIs at risk damage and losses? of flooding for the 1% annual probability flood event within this policy unit.

Landscape: The Sussex Downs AONB and the South Downs ESA and proposed National Park is located within this policy unit, however none of these areas are located within the 1% annual probability flood event outline.

Natural and Historic Environment: There are no listed buildings, registered historic parks and gardens or SMs at risk of fluvial flooding for the considered annual probability flood events in this policy unit. Environment Agency River Adur CFMP - Appendix B (September 2008) 146 What are the key factors that Climate change (increased rainfall). could drive future flood risk? What are the possible future It is predicted that climate change will increase the flood risk in this policy unit, levels of flood risk under the however, the extent to which this increase affects the people, property and main scenarios? environment in Brighton and Hove is unknown. There is potential to limit increased run-off from new development by installation What potential responses (or of SuDS and reduce or maintain current runoff from the south Downs in the future groups of responses) are through the adoption of agri-environmental schemes. There is also potential to being considered to manage provide integrated urban drainage solutions to reduce urban flooding. And also flood risk? the prevention of vulnerable development in flood risk areas. Flood risk from the sea is also a significant consideration in this policy unit. Therefore, fluvial flood risk management options must complement shoreline What gaps and uncertainties management plan policy and actions. are there in knowledge, and what assumptions have been We have estimated the future increase in flood risk within this policy unit on the made? best available prediction we have of climate change. Our current ability to accurately predict the impact of climate change, particularly the impact it will have on groundwater flooding, is limited.

The main sources of flooding for this policy unit are groundwater and surface water run-off. We have not been able to model these processes and it has therefore not been possible to define generic responses in this policy unit.

Environment Agency River Adur CFMP - Appendix B (September 2008) 147 Form B6 Appraisal of policy options against policy unit objectives Policy unit 6 – Brighton and Hove KEY = Scale of policy impact on objective: Not appraised Baseline Meets objective No impact Doesn’t meet object Uncertain The preferred policy option is indicated below by the policy option highlighted in pink Baseline (current Policy 1 Policy 2 Policy 3 Policy 4 Policy 5 Policy 6 and future) No maintenance Maintenance of the Localised protection undertaken on surface water and measures introduced. surface water and urban drainage Localised protection urban drainage Reduced level of networks continue. measures introduced. Current and future Upgrade of surface networks. maintenance of the Not considered baseline with current water and urban surface water and Continued support of Improvements to the feasible in this policy flood risk drainage networks to A do nothing urban drainage groundwater and surface water and unit. management. increase capacity and approach would networks. surface water flooding urban drainage meet design increase the flooding studies and research networks. Catchment Targets and Opportunities and in an unmanaged and such as the Flood 1 standards for the objectives Indicators Constraints unpredictable way. project. future. Economic objectives Opportunities - Provide development control advice to ensure no increase Targets in run-off from the new No significant increase development proposed in the in damages in Brighton South East Plan (e.g. Brighton and Hove). and Hove from surface - Reduce flood risk and water (including urban improve water quality by No maintenance of drainage flooding) and promoting and encourage the drainage networks As drainage networks Improved drainage groundwater due to use of SuDS in the proposed urban developments in The estimated and surface water and surface water The estimated networks and localised Increased local future changes (urban Brighton and Hove. damages resulting management management schemes damages resulting surface water defence works and Ensure flood damages development and Constraints from surface water schemes would lead decrease in condition from surface water protection measures upgrading of the do not significantly - Government and international climate change). and groundwater to a significant due to reduced and groundwater will mitigate the affects drainage network increase in Brighton and legislation, environmental management policies, plans flooding is currently increase in flooding maintenance the flooding will increase of climate change. The would reduce the Hove due to future Not applicable. Indicators and strategies for the approximately £1.4 with estimated estimated damages over time due to the estimated damages estimated damages change (urban Estimated* damages catchment must be complied million. This is likely damages resulting resulting from surface affects of climate resulting from surface resulting from surface development and with, such as accommodating resulting from surface to increase to slightly from surface water water and groundwater change to be slightly water and groundwater water and climate change). new housing within the water and groundwater catchment as detailed by the more than £1.4 million and groundwater flooding will increase to more than £1.4 flooding will remain at groundwater flooding flooding (£). South East Plan and in the future. flooding being be more than £1.4 million. approximately £1.4 to be minimal. compliance with the Habitats significantly more million. million. *Estimation based on historical Directive. damages observed in the - Steep catchments of the than £1.4 million. Brighton area from the 2000/ South Downs result in rapid 2001 flood event (Binnie Black run-off and quick responses & Veatch 2001 – Flood Defence to rainfall events. Assessment of Downland - CFMP objectives and policies Flooding). must complement those of the Shoreline Management Plan (SMP) that affects the CFMP area. Targets No maintenance of The level of Opportunities The current estimated Maintain a suitable level drainage networks emergency work Improved drainage - Improvements in the emergency work of emergency works efficiency of channel and and surface water remains at the current networks and localised expenditure is Increased local expenditure when flood defence maintenance management level with an surface water approximately £0.4 Emergency work is defence works and compared to estimated processes. schemes would lead estimated expenditure protection measures - Effective and efficient use of million; the estimated reduced with upgrading of the damages resulting from to a significant of approximately £0.4 will mitigate the affects Ensure that expenditure developer contributions for damages resulting expenditure reducing to drainage network surface water and flood risk management. increase in flooding. million. Estimated of climate change. on emergency surface from surface water less than £0.2 million. would reduce both groundwater flooding - To work with Defra and No expenditure is damages resulting Due to this the level of water and groundwater farmers to produce soil and groundwater Estimated damages the level of (£). incurred as no from surface water emergency works and flooding works is management plans which flooding are currently resulting from surface emergency work and have a benefit to flood risk emergency work is and groundwater estimated damages appropriate to the around £1.4 million, water and groundwater estimated flood Not applicable. Indicators through reducing the run-off undertaken. flooding are likely to remains the same are estimated damages increasing to slightly flooding are likely to be damages to be Balance of emergency rate. Estimated damages increase gradually around £0.4 million and resulting from surface Constraints more than £1.4 million substantially more than minimal. The works expenditure to resulting from surface over time due to the £1.4 million water and groundwater - Available funding for the in the future. £1.4 million. The balance of estimated* damages initial set up of new flood risk water and affects of climate respectively. flooding. balance of expenditure emergency work resulting from surface management schemes. groundwater flooding change to be slightly - Older flood defence The current balance of to damages is expenditure to water and groundwater increase to be more than £1.4 The balance of structures are likely to be expenditure to unacceptable. damages will be flooding (£). more costly to maintain. significantly more million. The balance expenditure to damages is acceptable. - Limited available information than £1.4 million. of expenditure to damages will remain *Estimation based on considered on surface water and The balance of damages will initially acceptable. historical damages groundwater flood damages. acceptable. observed in the Brighton expenditure to remain acceptable but Environment Agency River Adur CFMP - Appendix B (September 2008) 148 area from the 2000/ 2001 damages is may become flood event (Binnie Black & unacceptable. unacceptable over Veatch 2001 – Flood time. Defence Assessment of Downland Flooding).

Social objectives Opportunities - Provide development control advice to ensure no increase in run-off from the new development proposed in the South East Plan (e.g. Brighton and Hove). - Reduce flood risk and improve water quality by promoting and encourage the use of SuDS in the proposed Targets urban developments in No significant increase Brighton and Hove. - Continue local authority and No maintenance of Reduction in in the number of Environment Agency support drainage networks maintenance of Maintenance of properties affected by of the Flood 1 project in would result in an drainage networks drainage networks Improved drainage Increased local surface and groundwater relation to groundwater increase in the would result in an continues at the networks and localised flooding. An estimated 50 defence works and flooding in Brighton and frequency, extent and increase in the current level. protection measures - Develop a flood warning properties are at risk upgrading of the Hove in the future. system for groundwater depth of surface frequency, extent and will mitigate the affects of surface water and drainage network and Ensure the impact of flooding. water and depth of surface water The estimated number of climate change. groundwater flooding. warning service will surface water and Indicators - Continued practice and groundwater flooding. and groundwater of properties at risk of development of the This is likely to reduce the number of groundwater flooding on The estimated* number flooding. surface water and The estimated number Emergency Response Plan in increase to between properties at risk of properties does not of properties affected by Brighton and Hove, Worthing, The estimated groundwater is likely of properties at risk of Not applicable. 50 and 200 properties surface water and significantly increase in surface water and Shoreham, and Burgess Hill. number of properties The estimated number to increase to between surface water and - Influence the coastal defence in the future. groundwater flooding Brighton and Hove in the groundwater flooding. at risk of surface of properties at risk of 50 and 210. groundwater will strategy, along the Lower to zero. future. Adur, Teville Stream and water and surface water and remain at around 50. There is currently no *Surface water/ groundwater Ferring Rife, to improve the groundwater flooding groundwater flooding is No Flood Warning flooding estimates based on flood warning service No Groundwater sustainability of flood risk is likely to increase to likely to increase to Service provided but Groundwater Flood historical records. management in the this area. in Brighton and Hove. Flood Warning more than 600. more than 350. option continues to be Warning Service Constraints Service required. - Government and international explored for provided. Coverage of Flood legislation, environmental No Flood Warning No Flood Warning groundwater flooding. management policies, plans Warning Service and strategies for the Service provided Service provided catchment must be complied with, such as accommodating new housing within the catchment as detailed by the South East Plan and compliance with the Habitats Directive. - CFMP objectives and policies must complement those of the Shoreline Management Plan (SMP) that affects the CFMP area. Opportunities Targets - Reduce surface water run-off There are records of No increase in the and soil erosion by disruption and closure No maintenance of Improved drainage number of critical supporting the existing and of road/ rail links Reduction in Maintenance of future management policies drainage networks networks and localised infrastructure sites including the A23, maintenance of drainage networks regarding environmentally would result in an protection measures Increased local affected by surface Lewes Road and the drainage networks continues at the sensitive farming practices increase in the will mitigate the affects defence works and water and groundwater (e.g. those set out by main Brighton to would result in an current level. frequency, extent and of climate change. upgrading of the flooding in Brighton and Brighton and Hove City London railway line. increase in the Council). depth of surface drainage network will Hove and surrounding In addition two schools frequency, extent and There is likely to be a Ensure the disruption - Support the existing flood water and There will be no reduce surface water areas. defence measures in relation and a community depth of surface water gradual increase from caused by flooding to groundwater flooding. change from the and groundwater to surface water flooding, centre are also and groundwater the current extent of A transport and critical such as bunds provided by current extent of flooding. Indicators recorded as having flooding. roads, railway and Not applicable. infrastructure does not Brighton and Hove City Significantly more surface water and Number and period of been affected by critical infrastructure at increase in Brighton and Council. surface water and groundwater flooding No extent of A road, recorded A road and - Provide development control surface water flooding. More surface water risk of surface water Hove in the future. groundwater flooding with disruption and railway or critical railway closures due to advice to ensure no increase and groundwater and groundwater in run-off from the new of A roads, railway closures of the A23, infrastructure sites surface water and Records indicate that flooding of A roads, flooding due to the development proposed in the and critical Lewes Road and the will be affected by groundwater flooding*. South East Plan (e.g. surface water flooding railway and critical affects of climate infrastructure sites main Brighton to surface water and Brighton and Hove). persists for a infrastructure sites will change. Flooding is - Continue local authority and will occur and persist London railway line; groundwater flooding. Number of critical significant period of occur and persist for a likely to persist for a Environment Agency support for a significantly schools remain likely to infrastructure sites time (up to and more longer time period. longer time period. of the Flood 1 project in longer time period. be a affected. recorded as being relation to groundwater than two weeks). affected by surface flooding. - Develop a flood warning Environment Agency River Adur CFMP - Appendix B (September 2008) 149 water and groundwater system for groundwater Surface water and flooding. flooding*. Constraints groundwater flooding - Steep catchments of the is a known problem in *Surface water/ groundwater South Downs result in rapid this area and it is likely flooding estimates based on run-off and quick responses to increase in the historical records. to rainfall events. - Transport links in the future. catchment are a vital part of the communication network regionally, nationally and internationally, in particular the railways connecting London to the south coast and connecting the coastal towns and cities, the A23, A24, A27, A259, A283 and A2032. - CFMP objectives and policies must complement those of the Shoreline Management Plan (SMP) that affects the CFMP area. Opportunities - Reduce surface water run-off Targets and soil erosion by Reduction in the number supporting the existing and of properties affected by future management policies muddy flooding in regarding environmentally sensitive farming practices northern parts of (e.g. those set out by There will be a The impact of ‘muddy’ Brighton and Hove, Brighton and Hove City An estimated 25 The impacts of ‘muddy’ gradual increase in flooding will remain at Reduce the impact of Rottingdean, Council). properties are flooding will increase the impact of ‘muddy’ the current level, with - Support the existing flood The impacts of muddy flooding in Woodingdean, currently affected by with a decrease in flooding due to the an estimated 25 With increased defence measures in relation ‘muddy’ flooding will northern parts of Ovingdean and to surface water flooding, ‘muddy’ surface water maintenance of affects of climate properties being maintenance and increase with Brighton and Hove, Bevendean. such as bunds provided by flooding. This is likely watercourses and change. Flooding is affected, as local defence works Brighton and Hove City between 25 and 175 Not applicable. Rottingdean, to increase to between drainage networks. likely to occur more improvements in there are no incidents Council. properties being Woodingdean, Indicators Constraints 25 and 150 The number of frequently, to a greater maintenance and or associated impacts affected by this type Ovingdean and The estimated* number - Steep catchments of the approximately properties affected will depth. The estimated localised protection of ‘muddy’ flooding. of properties affected by South Downs result in rapid of flooding. Bevendean. run-off and quick responses properties in the increase to between 25 number of properties measures mitigate the Downland ‘muddy’ to rainfall events. future. and 150 affected increases to affects of climate surface water flooding*. - A suitable level of productivity between 25 and 125 change. from agricultural land needs * Estimates of properties to be retained. affected by muddy flooding - Visual impact of flood risk based on historical records. management activities within the proposed National park or Areas of Outstanding Natural Beauty. Environmental objectives There are no There are no There are no There are no There are no There are no There are no There are no There are no There are no environmental objectives environmental objectives environmental objectives environmental environmental environmental environmental environmental environmental environmental applicable to this policy applicable to this policy applicable to this policy objectives applicable objectives applicable objectives applicable to objectives applicable objectives applicable to objectives applicable objectives applicable unit. unit. unit. to this policy unit. to this policy unit. this policy unit. to this policy unit. this policy unit. to this policy unit. to this policy unit. Does this policy change flood risk locally or elsewhere: Unlikely to affect Unlikely to affect Unlikely to affect Unlikely to affect Unlikely to affect adjacent policy adjacent policy NA adjacent policy units adjacent policy units adjacent policy units units units

Environment Agency River Adur CFMP - Appendix B (September 2008) 150 Form B7 – Summary of losses and gains.

Policy unit Policy Unit 6 - Brighton and Hove name/number:

Preferred policy Policy options Losses Gains option relative to current baseline Policy option P1 Environmental NO LOSSES NO GAINS Not preferred option – The numbers of

properties, critical Social HIGH- NO GAINS infrastructure and transport routes affected The number of by surface water properties at risk of flooding is unacceptably surface water and urban high. Estimated drainage flooding will damages will also increase by more than increase to 550 unacceptable levels. Significantly more surface water and urban

drainage flooding to transport routes and critical infrastructure will

occur The number of properties affected by

‘muddy’ flooding will increase by up to 150

Economic HIGH- NO GAINS

Estimated damages caused by surface water flooding will increase significantly The balance of FRM expenditure to estimated damages is unacceptable with estimated damages increasing significantly Policy option P2 Environmental NO LOSSES NO GAINS Not preferred option – The numbers of

properties, critical Social HIGH- NO GAINS infrastructure and transport routes affected The number of by surface water properties at risk of flooding is unacceptably surface water and urban high. Estimated drainage flooding will damages will also increase by more than increase to 300 unacceptable levels. Substantially more surface water and urban

Environment Agency River Adur CFMP - Appendix B (September 2008) 151 drainage flooding to transport routes and

critical infrastructure will occur The number of

properties affected by ‘muddy’ flooding will increase by up to 125

HIGH- Economic NO GAINS Estimated damages caused by surface water flooding will increase substantially The balance of FRM expenditure to estimated damages is unacceptable with estimated damages increasing substantially Policy option P3 Environmental NO LOSSES NO GAINS Preferred Policy Option – Although there are

some losses in terms of Social LOW- NO GAINS the numbers if people and properties and the The number of level of disruption and properties at risk of AAD caused by surface water and urban flooding, the overall drainage flooding will strategy for this CFMP increase by up to 160 is to increase flood More surface water and storage upstream and urban drainage flooding thereby mitigate against to transport routes and future increases in flood critical infrastructure will risk due to climate occur change. The number of

properties affected by ‘muddy’ flooding will increase by up to 100

Economic MEDIUM- NO GAINS

Estimated damages caused by surface water flooding will increase The balance of FRM expenditure to estimated damages will become unacceptable with estimated damages increasing in the future Policy option P4 Environmental NO LOSSES NO GAINS Not preferred option – Although there are

additional benefits in Social NO LOSSES HIGH+ terms of the numbers of people and properties Environment Agency River Adur CFMP - Appendix B (September 2008) 152 The number of and reducing the level of properties at risk of disruption and AAD

surface water and caused by flooding, the urban drainage overall strategy for this flooding will not CFMP is to increase

increase in the future flood storage upstream Surface water and and thereby mitigate urban drainage against future increases

flooding to transport in flood risk due to routes and critical climate change. It infrastructure will not should therefore be

increase in the future unnecessary to further The number of increase FRM in this properties affected by policy unit in order to

‘muddy’ flooding will ensure risk does not not increase in the increase. future

Economic NO LOSSES HIGH+

Estimated damages caused by surface water flooding will not increase in the future The balance of FRM expenditure to estimated damages will remain acceptable with slight increases in FRM expenditure to maintain estimated damages at current levels in the future Policy option P5 Environmental NO LOSSES NO GAINS Not preferred option – Although there are

significant additional Social NO LOSSES HIGH+ benefits in terms of the numbers of people and The number of properties and properties at risk of minimising the level of surface water and disruption and AAD urban drainage caused by flooding, the flooding will be overall strategy for this reduced to 0 CFMP is to increase Surface water and flood storage upstream urban drainage and thereby mitigate flooding to transport against future increases routes and critical in flood risk due to infrastructure will be climate change. It minimised as far as should therefore be possible unnecessary to further The number of increase FRM in this properties affected by policy unit in order to ‘muddy’ flooding will ensure risk does not be reduced to 0 increase.

Environment Agency River Adur CFMP - Appendix B (September 2008) 153 Economic NO LOSSES HIGH+

Estimated damages caused by surface water flooding will be minimised The balance of FRM expenditure to estimated damages will be acceptable with increases in FRM expenditure to reduce estimated damages Policy option P6 Environmental Not applicable Not applicable Not preferred option – this Policy Option is not

considered feasible in Social this policy unit.

Economic

Environment Agency River Adur CFMP - Appendix B (September 2008) 154 objective. HIGH: High positive A policy has a ‘high positive’ effect where it could contribute to a social, economic or environmental objective in a significantly positive way. A ‘high positive’ effect could be: (i) a very large reduction in current flood risk; (ii) avoiding/reducing very large projected increases in flood risk under future conditions, and/or; (iii) significant additional social, economic and/or environmental gains. MEDIUM: Medium positive A policy has a ‘medium positive’ effect where it could contribute to a social, economic or environmental objective in a positive way. A ‘medium positive’ effect could be: (i) a reduction in current flood risk; (ii) avoiding/reducing projected increases in flood risk under future conditions, and/or; (iii) additional social, economic and/or environmental gains. LOW: Low positive A policy has a ‘low positive’ effect where it could make a limited contribution to a social, economic or environment objective, but where the overall contribution would be positive. A ‘low positive’ effect could be: (i) an overall reduction in current flood risk; (ii) an overall avoidance/reduction in flood risk under future conditions,

Environment Agency River Adur CFMP - Appendix B (September 2008) 155

Form B8 Summary of preferred policy Policy unit 6 – Brighton and Hove Physical characteristics: - Most densely populated policy unit, comprising Brighton and Hove, extending east to Rottingdean. Area of regional importance to the economy. - Chalk geology predominates with small pockets of Lambeth Group clays beneath Brighton. - There are no watercourses in this policy unit; there are however, several dry river valleys present. Flood mechanism: - Flashy response to surface water run-off. - Groundwater, urban drainage, and surface water flooding. Receptor: - People, properties and infrastructure in Brighton and Hove. - Main transport routes of A23, A27 (Lewes Road) and Brighton to London train line Problem/risk susceptible to groundwater and surface water flooding. Current Flood Risk Summary Number of properties estimated to be at risk of flooding 50 Estimated damages (based on 2000/01 event) £1.4 million Annual averages damages (approx.) - Future Flood risk: - Flood risk from groundwater and surface water flooding is currently assessed at low to medium; assessment remains low to medium in the future. - Anecdotal reports of rapid flooding to over 1m deep in some instances. Future Flood Risk Summary (in 100 years time) Number of properties at risk of flooding (1% annual probability flood event) 50 to 200 More than £1.4 Estimated damages (based on 2000/01 event) million Annual averages damages (approx.) - Policy 3 - Continue with existing or alternative actions to manage flood risk at the current Policy selected level (accepting that flood risk with increase over time from this baseline). This policy is appropriate where the current level of flood risk management is considered acceptable. Maintenance is minimal however assets are inspected. It is recognised that flood risk will change in the future, and management actions may change in time to gain efficiencies or improve effectiveness. This policy is appropriate for this policy unit for the following reasons: - The current level of flood risk is low to medium and it is not certain how this will increase in the future. Justification - The current flood risk management activities, carried out for the surface water, urban drainage and groundwater flooding problems, are considered appropriate and acceptable for the level of risk. - The selected policy would help achieve the catchment objectives to ensure the impact of flooding does not significantly increase. - A policy 6 option for policy unit 9 will also provide benefit to Brighton and Hove in the future. - Ensure flood damages do not significantly increase in Brighton and Hove due to future change (urban development and climate change). - Ensure that expenditure on emergency surface water flooding works is appropriate to the estimated damages resulting from surface water flooding. Catchment - Ensure the impact of surface water and groundwater flooding on properties does not objectives significantly increase in Brighton and Hove in the future. - Ensure the disruption caused by flooding to transport and critical infrastructure does not increase in Brighton and Hove in the future. - Reduce the impact of muddy flooding in northern parts of Brighton and Hove, Rottingdean, Woodingdean, Ovingdean and Bevendean. Opportunities: - Provide development control advice to ensure no increase in run-off from the new development proposed in the South East Plan (e.g. Brighton and Hove). Catchment-wide - Reduce flood risk and improve water quality by promoting and encourage the use of opportunities SuDS in the proposed urban developments in Brighton and Hove. and constraints - Improvements in the efficiency of channel and flood defence maintenance processes. - Effective and efficient use of developer contributions for flood risk management. - To work with Defra and farmers to produce soil management plans which have a benefit

Environment Agency River Adur CFMP - Appendix B (September 2008) 156 to flood risk through reducing the run-off rate. - Continue local authority and Environment Agency support of the Flood 1 project in relation to groundwater flooding. - Develop a flood warning system for groundwater flooding. - Continued practice and development of the Emergency Response Plan in Brighton and Hove, Worthing, Shoreham, and Burgess Hill. - Influence the coastal defence strategy, along the Lower Adur, Teville Stream and Ferring Rife, to improve the sustainability of flood risk management in the this area. - Reduce surface water run-off and soil erosion by supporting the existing and future management policies regarding environmentally sensitive farming practices (e.g. those set out by Brighton and Hove City Council). - Support the existing flood defence measures in relation to surface water flooding, such as bunds provided by Brighton and Hove City Council.

Constraints: - Government and international legislation, environmental management policies, plans and strategies for the catchment must be complied with, such as accommodating new housing within the catchment as detailed by the South East Plan and compliance with the Habitats Directive. - Steep catchments of the South Downs result in rapid run-off and quick responses to rainfall events. - CFMP objectives and policies must complement those of the Shoreline Management Plan (SMP) that affects the CFMP area. - Available funding for the initial set up of new flood risk management schemes. - Older flood defence structures are likely to be more costly to maintain. - Limited available information on surface water and groundwater flood damages. - Transport links in the catchment are a vital part of the communication network regionally, nationally and internationally, in particular the railways connecting London to the south coast and connecting the coastal towns and cities, the A23, A24, A27, A259, A283 and A2032. - A suitable level of productivity from agricultural land needs to be retained. - Visual impact of flood risk management activities within the proposed National Park or Areas of Outstanding Natural Beauty. Policy 1 - do nothing. This policy would not recognise the need to manage existing levels of flood risk.

Policy 2 - reduce current level of flood risk management. As with policy 1, this policy would not recognise the need to manage existing levels of flood risk.

Alternative Policy 4 – maintain the current level of flood risk into the future. This policy unit could also policies apply, however, it implies considerable increased flood risk management in the future. The considered need for this has not currently been identified or considered justifiable.

Policy 5 - reduce the level of flood risk, both now and in the future. The current level of risk is considered tolerable and therefore this policy is not justified.

Policy 6 - increase flooding to reduce flood risk elsewhere. Because of the large groundwater element of the flooding, there are no opportunities within this policy unit for this approach. Flood risk from the sea is also a significant consideration in this policy unit. Therefore, flood risk management options must fit with shoreline management plan policy and actions.

We have estimated the future increase in flood risk within this policy unit on the best available prediction we have of climate change (prior to the October 2006 Defra guidance). Our Uncertainties current ability to accurately predict the impact of this, particularly the impact climate change and will have on groundwater flooding, is limited. dependencies There is currently insufficient understanding of future flood risk from surface water and groundwater in this policy unit. The estimates made are indicative based on an assumption of increase runoff due to climate change and historic incidents of flooding. Further study into future flood risk and the cost of potential mitigation measures would facilitate more informed decision making and enable more confidence to be placed in the selected policy.

Environment Agency River Adur CFMP - Appendix B (September 2008) 157 Form B9 Requirements for further policy development and appraisal Policy unit 6 – Brighton and Hove Is there a need for further policy development? No If yes, then mark policy options for more detailed development. Some complex policies may require more detailed development, probably at Strategy Plan level. Is there a need for further more detailed appraisal? Yes If yes, take forward to strategy study.

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Form B10 Indicators for monitoring, review and evaluation This form sets out the indicators that need to be included in the policy implementation plan, for policy monitoring, drawing on the residual risks and likely impacts identified above. This will allow better review and evaluation of the policy when implemented. Policy unit 6 – Brighton and Hove Indicators to be included in policy unit 6 implementation plan are:

Economic - Estimated damages resulting from surface water and groundwater flooding (£) (based on historical damages). - Balance of emergency works expenditure to estimated damages resulting from surface water flooding (£) (based on historical damages).

Social - The estimated number of properties affected by surface water and groundwater flooding (based on historical records). - Number and period of recorded A road and railway closures due to surface water and groundwater flooding (based on historical records). - Number of critical infrastructure sites recorded as being affected by surface water and groundwater flooding (based on historical records). - The estimated number of properties affected by Downland ‘muddy’ surface water flooding (based on historical records).

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Policy unit 7 Shoreham and Adur Estuary Policy appraisal forms Form B5 – Summary of current and future levels of and responses to flood risk. Form B6 – Appraisal of policy options against policy unit objectives. Form B7 – Summary of losses and gains. Form B8 – Summary of preferred policy. Form B9 – Requirements for further policy development and appraisal. Form B10 – Indicators for monitoring, review and evaluation.

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Form B5 Summary of current and future levels or and responses to flood risk Policy unit 7 – Shoreham and Adur Estuary Defences: There are 9km of raised flood defences along the River Adur on both sides of the river. The unit also includes the locked harbour that is on a spur from the east back of the River Adur. It is controlled by two harbour arms. Shingle builds against the western arm and material is by-passed eastwards to help reinforce the narrow, timber groyned beach fronting the Harbour. Other defences along the banks of the tidal Adur consist of steel sheet piled walls, reinforced concrete walls, rock groynes, shingle and earth embankments.

Current responses to flood risk Flood Warning: This policy unit is covered by the River Adur, downstream of within the policy unit Upper Beeding to Norfolk Bridge at Shoreham, fluvial Flood Warning Area and also from the coastal areas. There are more than 810 properties connected to the flood warnings direct service.

Maintenance: We currently carry out annual inspection and maintenance of the tidal embankments. The estimated cost of maintaining the channels and existing defences under the Environment Agency’s responsibility is approximately £80,000. Standard of protection: The raised embankments along the River Adur are Standards of service that apply considered to offer protection ranging from the 20% (1 in 5) to the 0.5% (1 in 200) to flood defences within the annual probability events (fluvial and tidal). They are considered to be at or policy unit above the target condition. In 10% flood In 1% flood In 0.1% flood Receptors outline* outline* outline* Residential properties 0 1 344 Commercial properties 10 10 N/A Population 0 2 822 Property damages £383,000 £383,000 N/A Agricultural damages £805 £805 N/A A roads 0.06 km 0.06 km 5.98 km Railways 0.10 km 0.10 km 2.93 km Agricultural land Grade 1 0 km2 0 km2 0.42 km2 Agricultural land Grade 2 0 km2 0 km2 0.20 km2 What is currently exposed to Agricultural land Grade 3 0.03 km2 0.03 km2 2.51 km2 flooding? Agricultural land Grade 4 0 km2 0 km2 0 km2 Agricultural land Grade 5 0 km2 0 km2 0 km2 SNCIs 0 km2 0 km2 0.09 km2 SSSI 0.01 km2 0.01 km2 0.5 km2 Listed Buildings 0 0 0 SM 0 0 2 AONB 0.0004 km2 0.0004 km2 0.22 km2 ESA 0 km2 0 km2 0.04 km2 Registered Historic Parks 2 2 2 and Gardens 0 km 0 km 0 km Proposed National Park 0 km2 0 km2 0.04 km2 * 10% and 1% based on broadscale model results and 0.1% based on Flood Zone 2 Economic and social receptors: The broadscale model results show approximately 10 properties and 2 people are at risk of tidally influenced fluvial flooding in this policy unit, for the 1% annual probability flood event.

Shoreham airport and sections of the A259 are at risk of flooding from the 10% and 1% annual probability flood events; sections of the A27 are at risk of flooding Who and what are currently from the 0.1% annual probability flood event with the around 6km of A road at risk most vulnerable to flood of flooding. damage and losses? A short length of the railway is located within the 10% and 1% annual probability flood event outlines, this increases to almost 3km for the extreme flood event.

Environmental designations: A minor extent of the Adur Estuary SSSI is located within 1% annual probability flood event outline.

Environment Agency River Adur CFMP - Appendix B (September 2008) 161 No SNCIs within this policy unit are at risk of flooding during the 10% or 1% annual probability flood event. A small extent of the Widewater Lagoon SNCI is located within the extreme event flood outline.

Landscape: A small extent of the Sussex Downs AONB is located within the 1% annual probability flood event outline within this policy unit.

Natural and Historic Environment: There are no listed buildings, registered historic parks and gardens, SMs or natural environments (i.e. wet woodlands) at risk of flooding for the 1% annual probability flood event. Sea level rise resulting from the effects of climate change*. Increased urbanisation will place more people and property in areas at risk.

What are the key factors that *To represent future sea level rise, the tidal boundary within the broadscale model was scaled to increase the maximum still water level by 600mm for the 100 year timescale. These climate change could drive future flood risk? figures used were the accepted approach for ‘typical’ catchments when the scoping stage broadscale modelling was carried out. Since the scoping stage was completed new Defra guidance (October 2006) on climate change has been released which suggest that for a 100 year time scale, sea level may rise by almost 1m. Therefore the results from the broadscale model in the tidally influenced areas are likely to have under predicted the increase in flood risk and damages in the future. There is a large increase in AAD from fluvial flooding expected due to climate What are the possible future change over the next 100 years from fluvial flooding alone. levels of flood risk under the

main scenarios? The number of properties at risk in the future increases to more than 1750. What potential responses (or Improve existing or construct new defences. This policy unit is unsuitable for groups of responses) are large scale attenuation; small scale attenuation is unlikely to successfully manage being considered to manage flood risk alone as the flood risk is predominantly tidally influenced. flood risk? Flood risk from the sea is a significant consideration in this policy unit. Therefore, fluvial flood risk management options must fit with the shoreline management plan policy and actions.

We have estimated the future increase in flood risk within this policy unit on the best available prediction we have of climate change, frequency and size of storms and flood events in the future.

What gaps and uncertainties The broadscale model has not included the drainage network through the are there in knowledge, and Shoreham Airport site. This area is at risk from overtopping of the Adur and also what assumptions have been from groundwater and surface water run-off. There is, therefore, some made? uncertainty in the resulting flood extent and severity – particularly in the long- term. We have taken this uncertainty into account when selecting the most appropriate policy, but we must look at this again at the next CFMP review.

Environment Agency River Adur CFMP - Appendix B (September 2008) 162 Generic response: Rural land use change – changing farming practices to reduce run-off rates 1% annual probability fluvial flood Results from broadscale modelling damages (£m)

There is a clear reduction in flood damages in the policy units further Future basecase = £0.008 upstream, but there is no noticeable effect in this policy unit at the downstream Generic response = £0.008 end of the River Adur. % change = 0% Conclusions The flood mechanisms in policy unit 7 are dominated by tidal influences. The reduction in run-off rates in the upper parts of the Adur catchment has no impact on flood depths or extent within this policy unit.

Generic response: Attenuation/retention (storage) on the Adur West Branch 1% annual probability fluvial flood Results from broadscale modelling damages (£m) There is a clear reduction in flood damages in the policy units further Future basecase = £0.008 upstream, but there is no noticeable effect in this policy unit at the downstream end of the River Adur from flood storage measure in the upper parts of the Generic response = £0.008 catchment. % change = 0% Conclusions The flood mechanisms in policy unit 7 are dominated by tidal influences. Flood attenuation in the upper parts of the Adur catchment has no impact on flood depths or extent within this policy unit.

Generic response: Barrier across the River Adur at Shoreham 1% annual probability fluvial flood Results from broadscale modelling damages (£m) This case looks at the situation where a barrier is built across the mouth of the river that keeps the tide out, but allows free discharge of the river into the sea Future basecase = £0.008 at low tide. The modelling has shown that the reduction in flooding through Generic response = £0.0 this approach is significant for the 1% annual probability fluvial flood event within this policy unit, with a 100% reduction in flood damages. % change = -100% Conclusions In this policy unit, this approach has shown to be effective at virtually eliminating flood damages for fluvial flooding.

There is a wide and complex range of combined fluvial and tidal events that can currently result in flooding. It is therefore not possible to say with confidence what the overall effect of this option would be under different conditions.

Generic response: Reducing the height of all raised embankments along the River Adur 1% annual probability fluvial flood Results from broadscale modelling damages (£m) Reducing the height of the embankments along the River Adur represents the Future basecase = £0.008 case of ‘do nothing’. The results from the modelling of this option show as expected in this policy unit, a large amount of additional flood extent and flood Generic response = £77.284 damage. % change = >1,000% Conclusions The impact of reducing the height of the raised embankments on flooding within this policy unit is large. Flooding would occur frequently, with Shoreham being flooded by a 20% annual probability fluvial flood event.

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Form B6 Appraisal of policy options against policy unit objectives Policy unit 7 – Shoreham and Adur Estuary KEY = Scale of policy impact on objective: Not appraised Baseline Meets objective No impact Doesn’t meet object Uncertain The preferred policy option is indicated below by the policy option highlighted in pink Baseline (current Policy 1 Policy 2 Policy 3 Policy 4 Policy 5 Policy 6 and future) No maintenance of watercourses. Channels become blocked with vegetation and Reduction in conveyance is maintenance of Improved level of reduced. watercourses. channel maintenance Channels become Maintenance of the Construct a barrier The height of raised of watercourses. blocked with vegetation channels continues. across the River Adur embankments would and conveyance is within this policy unit. reduce over time. reduced. The flood warning Localised protection Current and future service remains in measures introduced. Upgrade of surface Not considered baseline with current The flood warning The flood warning place. water and urban feasible in this policy flood risk service is withdrawn. service remains in drainage networks to unit. management. The flood warning place. Maintenance of the increase capacity and No maintenance service is improved. surface water and meet design undertaken on Reduced level of urban drainage standards for the surface water and Improvements to the maintenance of the networks continue. future. urban drainage surface water and surface water and networks. urban drainage urban drainage networks. networks. A do nothing approach would increase the flooding Catchment Targets and Opportunities and in an unmanaged and objectives Indicators Constraints unpredictable way. Economic objectives Opportunities - Provide development control advice to ensure no increase Targets in run-off from the new No significant increase development proposed in the No maintenance of South East Plan (e.g. channels and a in damages in The current total Shoreham). reduction in the Shoreham from fluvial, annual average - Reduce flood risk and height of the surface water and urban improve water quality by damages from fluvial As channels decrease The total annual embankments would Improved channel drainage flooding due to promoting and encourage the flooding are in conveyance and average damages use of SuDS in the proposed lead to a significant maintenance and future changes (urban approximately capacity due to from fluvial flooding The construction of a urban developments in increase in flooding localised protection development and Shoreham. £77,000; this reduced maintenance will increase over time barrier across the with total annual measures will mitigate climate change). - Investigate removal of increases to around the total annual due to the affects of River Adur and Environment Agency owned average damages the affects of climate £15 million in the average damages from climate change to be upgrading of surface and maintained existing from fluvial flooding change. The total Ensure flood damages Indicators future. fluvial flooding will approximately £15 water and urban raised defences to reinstate increasing to more annual average do not significantly Total annual average the floodplain between increase to be more million. drainage networks than £20 million. damages from fluvial increase in Shoreham damages (to properties Steyning and Shoreham to a There are reports of than £17 million. would reduce total naturally functioning state, to flooding will remain at Not applicable. due to future change and agriculture) from surface water flooding There are limited annual average provide flood storage and No maintenance will approximately £77,000. (urban development and fluvial flooding (£AAD). enhance conservation value to the west of the There will be a report of surface water damages from fluvial lead to a significant climate change). and biodiversity. policy unit, however substantial increase flooding, however, it is flooding and - Potential for improving the increase from the Surface water flooding Estimated* damages these were not from the current level likely there will be an damages from current defences, for current level of and associated resulting from surface sufficient to enable of surface water increase in surface surface water example possible installation surface water damages will remain at water and groundwater of demountable or temporary estimates of the flooding and water flooding and flooding to be flooding and the current levels due flooding (£). defences in Shoreham and damages. Surface associated damages associated damages minimal. Burgess Hill. associated damages. to improvements to the Constraints water flooding is a with a reduction in due to the affects of *Estimation based on historical drainage networks. - Government and international damages observed in the known problem in this maintenance. climate change. legislation, environmental Withdrawing the flood Brighton area from the 2000/ area and it is likely to management policies, plans warning system may 2001 flood event (Binnie Black and strategies for the increase in the future. & Veatch 2001 – Flood Defence result in increased catchment must be complied Assessment of Downland with, such as accommodating risk to human life. Flooding). new housing within the catchment as detailed by the South East Plan and Environment Agency River Adur CFMP - Appendix B (September 2008) 164 compliance with the Habitats Directive. - Steep catchments of the South Downs result in rapid run-off and quick responses to rainfall events. - CFMP objectives and policies must complement those of the Shoreline Management Plan (SMP) that affects the CFMP area. The level of channel Opportunities The current annual The level of channel Targets and flood defence - Improvements in the channel and flood Channel and flood and flood defence Maintain a suitable efficiency of channel and No channel and flood maintenance defence maintenance defence maintenance maintenance balance of annual river flood defence maintenance defence maintenance Channel and flood expenditure will expenditure is expenditure remains expenditure will channel and flood processes. expenditure is defence maintenance increase over time to - Effective and efficient use of approximately at approximately increase to be defence maintenance incurred as no expenditure reduces to mitigate the affects of developer contributions for £80,000; the annual £80,000. Annual significantly more Ensure that river expenditure (£) to flood risk management. maintenance is be less than £35,000. climate change to more average damages average damages than £80,000. channel and flood annual average - To work with Defra and undertaken. Annual Annual average than £80,000. Annual farmers to produce soil from flooding to from fluvial flooding to Annual average defence maintenance damages from fluvial average damages damages from fluvial average damages from management plans which property are currently property increase over damages from fluvial expenditure is flooding to property (£). have a benefit to flood risk from fluvial flooding flooding to property are fluvial flooding to around £77,000, time due to the affects flooding to property Not applicable. appropriate to the through reducing the run-off to property increase likely to be more than property will remain increasing to around of climate change to are estimated to be property economic Indicators rate. to be more than £20 £17 million. around £77,000. Constraints £15 million in the be around £15 million. £0. damage in urban areas Balance of annual river million. - Available funding for the future. from flooding. channel and flood initial set up of new flood risk The balance of With better The balance of The balance of defence maintenance management schemes. The balance of expenditure to maintenance efficiency - Older flood defence The current balance of expenditure to expenditure to expenditure (£) to expenditure to damages is and effective use of structures are likely to be expenditure to damages is damages will be annual average more costly to maintain. damages is unacceptable. funding the balance of damages is considered to be unacceptable with damages from fluvial - Limited available information unacceptable. expenditure to considered unacceptable. expenditure being flooding to property (£). on surface water and damages will remain groundwater flood damages. acceptable. unjustifiably high. acceptable. Social objectives Opportunities - Provide development control advice to ensure no increase Approximately 10 in run-off from the new No maintenance of Reduction in people and 2 development proposed in the channels and a maintenance of South East Plan (e.g. properties are at risk reduction in the channels and surface Shoreham). of localised fluvial Improved channel Targets height of water and urban Maintenance of - Reduce flood risk and flooding by the current maintenance, drainage No significant increase improve water quality by embankments would drainage networks channels and 1% annual probability networks and localised in the number of people promoting and encourage the result in a significant would result in an drainage networks use of SuDS in the proposed flood event. This protection measures or properties affected by increase in the increase in the continues at the The construction of a urban developments in increases to more will mitigate the affects the 1% annual Shoreham. frequency, extent and frequency, extent and current level. barrier across the than 4200 people and of climate change. The probability fluvial flood - Continued practice and depth of fluvial and depth of fluvial and River Adur would development of the more than 1750 number of people and event or surface water surface water and surface and urban The number of people reduce the number of Emergency Response Plan in properties in the properties affected by flooding in Shoreham in urban drainage drainage flooding. and properties at risk people and properties Brighton and Hove, Worthing, future. fluvial flooding will the future. and Shoreham. flooding. of localised fluvial affected by fluvial remain at - Investigate removal of It is likely that the flooding is likely to flooding to none. Environment Agency owned There are limited approximately 2 and 10 Indicators The number of number of people and increase to slightly and maintained existing historic reports of respectively. Ensure the impact of Number of people and raised defences to reinstate people and properties properties at risk of more than 4200 and No properties will be surface water and flooding on people and properties affected by the floodplain between at risk of fluvial fluvial flooding will 1750 respectively. at risk of surface Steyning and Shoreham to a urban drainage The estimated number property does not the 1% annual flooding will increase increase to be water and urban Not applicable. naturally functioning state, to flooding and therefore of properties at risk of significantly increase in probability fluvial flood to be significantly substantially more than Over time the number drainage flooding due provide flood storage and we have not been able surface water and Shoreham in the future. event. enhance conservation value more than 4200 and 4200 and 1750 of properties at risk of to upgrading of to estimate the urban drainage and biodiversity. 1750 respectively. respectively. surface water and surface water and - Influence the coastal defence number of properties flooding will remain at The estimated* number urban drainage urban drainage strategy, along the Lower affected by these the current level due to of properties affected by Adur, to improve the There will be a There will be a flooding will increase networks. sources of flooding. improvements to the surface water and sustainability of flood risk significant increase substantial increase from the current level management in the this area. However, surface drainage networks. groundwater flooding. from the current from the current level in due to the affects of Flood Warning Constraints water and urban number of properties the number of climate change. Service is improved - Government and international drainage flooding is a Coverage of Flood *Surface water/ groundwater legislation, environmental affected by surface properties affected by in terms of accuracy flooding estimates based on known problem in this Warning Service is management policies, plans water and urban surface water and The current level of and coverage historical records. and strategies for the area and it is likely to increased, system is drainage flooding. urban drainage Flood Warning catchment must be complied increase in the future improved in terms of Coverage of Flood with, such as accommodating flooding. Service remains in accuracy and Warning Service new housing within the Withdrawing the flood place. catchment as detailed by the A flood warnings coverage. warning system may The current level of South East Plan and service is currently result in increased Flood Warning Service compliance with the Habitats available to 1435 Directive. risk to human life. remains in place. - Visual impact of flood risk properties. management activities within the proposed National Park Environment Agency River Adur CFMP - Appendix B (September 2008) 165 or Areas of Outstanding Natural Beauty. - CFMP objectives and policies must complement those of the Shoreline Management Plan (SMP) that affects the CFMP area.

Opportunities - Reduce surface water run-off and soil erosion by Targets supporting the existing and future management policies No increase in flooding regarding environmentally of A roads and railway sensitive farming practices. line or increase in extent - Support the existing flood defence measures in relation of critical infrastructure No maintenance of to surface water flooding. Currently flooded, in Shoreham - Provide development control channels and approximately 0.06km and surrounding areas, advice to ensure no increase drainage networks of A road (A259) and from a 1% annual in run-off from the new and a reduction in the Reduction in development proposed in the 0.1km of railway are Improved channel probability fluvial flood height of maintenance of South East Plan (e.g. affected by the 1% Maintenance of maintenance, drainage event or surface water Shoreham). embankments would channels and drainage annual probability channels and networks and localised flooding. - Potential for improving the result in an increase networks would result current defences, for flood event. drainage networks protection measures in the frequency, in an increase in the The construction of a example possible installation No critical continues at the will mitigate the affects Indicators of demountable or temporary extent and depth of frequency, extent and barrier across the infrastructure sites are current level. of climate change. Length of A road and defences in Shoreham and fluvial and surface depth of fluvial and River Adur and affected. railway line (km) affected Burgess Hill. and urban drainage surface and urban upgrading of surface - Investigate removal of Due to the railway Approximately 0.06km by the 1% annual flooding. drainage flooding. water and urban Environment Agency owned In the future there is being raised on of A road and 0.1km of probability fluvial flood and maintained existing drainage networks only a minor increase embankment in the railway remain affected Ensure the disruption event. raised defences to reinstate More than 1km of A More than 0.5km of A would reduce fluvial the floodplain between in length of A road future there is only a by flooding during the caused by flooding to road and 1.5 km of road and 1km of and surface water Steyning and Shoreham to a (A259) is affected by minor increase in 1% annual probability transport and critical Number of critical naturally functioning state, to railway, four railway is likely to be at and urban drainage the 1% annual length of A road flood event. Not applicable. infrastructure does not infrastructure sites provide flood storage and electricity sub risk of flooding from flooding. probability flood event. affected by the 1% increase in Shoreham in affected by the 1% enhance conservation value stations, one hospital fluvial flooding during and biodiversity. annual probability With improvements to the future. annual probability fluvial and the Lancing the 1% annual No extent of A road, Constraints There are no records flood event. the surface water and flood event. - Steep catchments of the police station are probability flood event. railway or critical of A road, railway and urban drainage South Downs result in rapid likely to be at risk of infrastructure sites run-off and quick responses critical infrastructure There will be an networks there will be Number and period of flooding from fluvial More surface water will be affected by to rainfall events. sites being affected by increase, from the no change from the recorded A road and - Transport links in the flooding during the and urban drainage fluvial or surface surface water and current risk, of surface current extent of railway closures due to catchment are a vital part of 1% annual probability flooding of A road and water and urban urban drainage water and urban surface water and surface water and the communication network flood event. railway. Surface water drainage flooding. regionally, nationally and flooding, however, drainage flooding to A urban drainage groundwater flooding*. and urban drainage internationally, in particular surface water and roads and critical flooding to A roads, the railways connecting Substantially more flooding may affect urban drainage infrastructure sites. railway line and critical Number of critical London to the south coast surface water and some critical and connecting the coastal flooding is a known infrastructure sites. infrastructure sites urban drainage infrastructure sites. towns and cities, the A23, problem in this area recorded as being A24, A27, A259, A283 and flooding of A roads, and it is likely to affected by surface A2032. railway and critical water and groundwater - Visual impact of flood risk increase in the future. management activities within infrastructure sites. flooding*. the proposed National Park or Areas of outstanding *Surface water/ groundwater Natural Beauty. flooding estimates based on - CFMP objectives and policies historical records. must complement those of the Shoreline Management Plan (SMP) that affects the CFMP area. Environmental objectives Opportunities There is currently Doing nothing and Reducing the This is a small The construction of a - Help meet national 0.01km2 of the SSSI reducing the height of maintenance of the increase to around The extent of the SSSI barrier across the biodiversity action plan (BAP) 2 targets. located within the 1% embankments would channels and surface 0.02km in the area of within the 1% annual River Adur and Targets - Investigate removal of annual probability allow the rivers to water and urban the SSSI within the probability flood event upgrading of surface Environment Agency owned outline will remain at Protect and enhance the and maintained existing flood event outline. flood more frequently drainage networks 1% annual probability water and urban Adur Estuary SSSI. and increase the would eventually allow flood event outline due approximately 0.01km2. drainage networks Protect and enhance the raised defences to reinstate the floodplain between There is a small flood depths, the rivers to flood more to the affects of will reduce the extent Not applicable. Adur Estuary SSSI. Indicators Steyning and Shoreham to a increase to around increasing the area of frequently and increase climate change in the There will be no of flooding and naturally functioning state, to 2 Habitat quality and provide flood storage and 0.02km of the SSSI the SSSI within the the flood depths, future, however, it is notable change in the therefore the extent species diversity. enhance conservation value located within the 1% 1% annual probability increasing the area of likely that there will be habitat and species of the SSSI within the and biodiversity. annual probability flood outline to the SSSI within the 1% no notable increase in diversity within the 1% annual probability Constraints flood event outline in substantially more annual probability flood habitat and species SSSI. flood outline to less - Some environmentally 2 2 designated habitats are the future. It is likely than 0.2km . outline to more than diversity with such a than 0.01km . Environment Agency River Adur CFMP - Appendix B (September 2008) 166 susceptible to changes in that there will be no 0.1km2. minor increase. flood frequency, floodwater chemistry, groundwater notable increase in There is increased Decrease in flooding levels and drainage system habitat and species potential to There is increased extent (duration and maintenance. diversity with such a substantially improve potential to improve or depth) will reduce the - Changes to flood risk minor increase. or increase the increase the habitat potential of management can affect the landscape, its character and habitat types and types and species increasing habitat value as an amenity. species diversity diversity within the types and species - CFMP objectives and policies within the SSSI. SSSI. However, this diversity within the must complement those of the Shoreline Management However, this would would occur in an SSSI. Plan (SMP) that affects the occur in an unmanaged way. CFMP area. unmanaged and uncontrolled way. Opportunities - Help meet national biodiversity action plan (BAP) The construction of a targets. barrier across the - Investigate removal of The area of the River Adur and Environment Agency owned There is currently Sussex Downs upgrading of surface and maintained existing 2 The area of the 0.0004km of the AONB located within The area of the Sussex water and urban raised defences to reinstate Sussex Downs AONB The area of the Sussex the floodplain between Sussex Downs AONB the 1% annual Downs AONB located drainage networks located within the 1% Downs AONB located Steyning and Shoreham to a located within the 1% probability flood within the 1% annual will reduce frequency Targets naturally functioning state, to annual probability within the 1% annual annual probability event outline probability flood event and depth of flooding Increase the landscape provide flood storage and flood event outline probability flood event enhance conservation value flood event outline. increases to be more outline increases to be and therefore have a character value of the 2 2 increases over time to outline remains at and biodiversity. This increases by a than 0.05km . more than 0.02km . 2 negative impact on Increase the landscape Sussex Downs AONB. Constraints slightly more than around 0.0004km . minor extent to slightly 2 the landscape character value of the - Some environmentally 2 0.0004km . Not applicable. more than 0.0004km The landscape The landscape character of the Sussex Downs. Indicators designated habitats are There would be no susceptible to changes in in the future. character of the character of the Sussex Downs Landscape character There would be no impact on the flood frequency, floodwater Sussex Downs Sussex Downs AONB AONB. assessment of the chemistry, groundwater notable impact on the landscape character of The landscape AONB is likely to alter is likely to alter in a AONB. levels and drainage system landscape character the Sussex Downs character of the in a beneficial beneficial manner, The area of the maintenance. of the Sussex Downs AONB in this policy - Changes to flood risk Sussex Downs AONB manner, however, it however, it will occur in Sussex Downs AONB in this policy unit. management can affect the is unlikely to notable will occur in an an unmanaged way. AONB located within landscape, its character and unit. value as an amenity. alter. unmanaged and un the 1% annual - CFMP objectives and policies controlled way. probability flood must complement those of event outline the Shoreline Management Plan (SMP) that affects the decreases to be nil. CFMP area. Does this policy change flood risk locally or elsewhere: Unlikely to affect Unlikely to affect Unlikely to affect Unlikely to affect Unlikely to affect adjacent policy adjacent policy NA adjacent policy units adjacent policy units adjacent policy units units units

Environment Agency River Adur CFMP - Appendix B (September 2008) 167 Form B7 – Summary of losses and gains.

Policy unit Policy Unit 7 - Shoreham and Adur Estuary name/number:

Preferred policy Policy options Losses Gains option relative to current baseline Policy option P1 Environmental NO LOSSES HIGH+ Not preferred option – There are limited gains The area of the Adur under this policy option. Estuary SSSI will The numbers of people increase by more than 2 and properties 0.19km but in an adversely affected by unmanaged and removing FRM are uncontrolled way unacceptably high. The The landscape value AAD and level of of the Sussex Downs disruption caused by will be likely to alter in flooding are also high a beneficial way but in and the environmental an unmanaged and effects are uncontrolled way unpredictable due to the

unmanaged and Social HIGH- NO GAINS uncontrolled nature of this policy option. The number of people and properties at risk of

localised fluvial flooding in a 1% AEP flood event will increase by

significantly more than 4198 and 740 respectively

The number of properties at risk of surface water and urban

drainage flooding will increase significantly Withdrawing the flood

warning system will increase risk to human life

The lengths of A road and railway at risk from a 1% AEP flood event

will increase by more than 0.94km and 1.4km respectively

The critical infrastructure at risk from a 1% AEP flood event will increase

by 4 electricity substations, 1 hospital and 1 police station

Substantially more surface water and urban drainage flooding to

Environment Agency River Adur CFMP - Appendix B (September 2008) 168 transport routes will occur

Economic NO GAINS HIGH-

The AAD to properties and agricultural land caused by fluvial flooding will increase by more than £19.9 million AAD to properties and agricultural land caused by surface water flooding will increase significantly The balance of FRM expenditure to AAD is unacceptable with AAD to properties and agricultural land increasing by more than £19.9 million Policy option P2 Environmental NO LOSSES MEDIUM+ Not preferred option – There are limited gains The area of the Adur under this policy option. Estuary SSSI will The numbers of people increase by more than 2 and properties 0.09km but in an adversely affected by unmanaged way reducing FRM are The landscape value unacceptably high. The of the Sussex Downs AAD and level of will be likely to alter in disruption caused by a beneficial way but in flooding are also high an unmanaged way and the environmental

effects are

unpredictable due to the Social HIGH- NEUTRAL= unmanaged nature of The number of people The number of critical this policy option. and properties at risk of infrastructure at risk

localised fluvial flooding from a 1% AEP flood in a 1% AEP flood event event will remain at 0 will increase by

substantially more than

4198 and 740 respectively

The number of

properties at risk of surface water and urban

drainage flooding will

increase substantially The lengths of A road

and railway at risk from

a 1% AEP flood event will increase by more

than 0.44km and 0.9km

respectively More surface water and

urban drainage flooding

to transport routes will Environment Agency River Adur CFMP - Appendix B (September 2008) 169 occur

NO GAINS HIGH- Economic The AAD to properties and agricultural land caused by fluvial flooding will increase by more than £16.9 million AAD to properties and agricultural land caused by surface water flooding will increase substantially The balance of FRM expenditure to AAD is unacceptable with AAD to properties and agricultural land increasing by more than £16.9 million Policy option P3 Environmental NO LOSSES MEDIUM+ Not preferred option – The numbers of people The area of the Adur and properties Estuary SSSI will adversely affected by increase by 2 removing FRM are approximately 0.01km substantial. The AAD

and level of disruption LOW+ caused by flooding are

also high. The areas of the

Sussex Downs AONB and South Downs ESA/proposed NP that

fall within the 1% AEP will increase slightly but with no notable

increase in landscape value

Social MEDIUM- MEDIUM+

The number of people The length of railway and properties at risk of at risk from a 1% AEP

localised fluvial flooding flood event will not in a 1% AEP flood event increase in the future will increase by

approximately 4198 and NEUTRAL= 740 respectively The number of The number of critical

properties at risk of infrastructure at risk surface water and urban from a 1% AEP flood drainage flooding will event will remain at 0

increase in the future The length of A road at

risk from a 1% AEP

flood event will increase slightly

Surface water and urban Environment Agency River Adur CFMP - Appendix B (September 2008) 170 drainage flooding to transport routes will

increase slightly

Economic MEDIUM- NO GAINS

The AAD to properties and agricultural land caused by fluvial flooding will increase by approximately £14.9 million AAD to properties and agricultural land caused by surface water flooding will increase in the future The balance of FRM expenditure to AAD is unacceptable with AAD to properties and agricultural land increasing by approximately £14.9 million Policy option P4 Environmental LOW- LOW+ Preferred Policy Option – There are few losses The area of the Sussex The area of the Adur under this policy. The Downs that falls within Estuary SSSI will not numbers of people and the 1% AEP remain the increase in the future properties affected by same with no increase in with no notable flooding and the landscape value change in habitat and disruption caused will species diversity not increase in the

future. The AAD and Social NO LOSSES HIGH+ economic damages will remain constant and the The number of people associated future FRM and properties at risk expenditure will be of localised fluvial efficient. flooding in a 1% AEP flood event will not

increase in the future The number of properties at risk of

surface water and urban drainage flooding will not

increase in the future The lengths of A road and railway at risk

from a 1% AEP flood event will not increase in the future

NEUTRAL=

The number of critical infrastructure at risk from a 1% AEP flood

Environment Agency River Adur CFMP - Appendix B (September 2008) 171 event will remain at 0

HIGH+ Economic NO LOSSES The AAD to properties and agricultural land caused by fluvial flooding will not increase in the future AAD to properties and agricultural land caused by surface water flooding will not increase in the future The balance of FRM expenditure to AAD is acceptable with increases in FRM expenditure to significantly reduce AAD to properties and agricultural land Policy option P5 Environmental MEDIUM- NO GAINS Not preferred option – Although there are The area of the Adur additional gains in terms Estuary SSSI will be of reducing the numbers reduced with a possible of people and properties decline in habitat and affected by flooding and species diversity minimising the The area of Sussex disruption it causes, Downs that falls within these benefits are the 1% AEP will be marginal in relation to decreased which will additional FRM impact negatively on the expenditure. This option landscape value is therefore not efficient.

There are also Social NO LOSSES HIGH+ significant negative The number of people environmental impacts and properties at risk associated with this

of localised fluvial policy option. flooding in a 1% AEP flood event will be

reduced The number of properties at risk of

surface water and urban drainage flooding will be

reduced to 0

NEUTRAL=

The number of critical infrastructure at risk

from a 1% AEP flood event will remain at 0

HIGH+ Economic MEDIUM- AAD to properties and Environment Agency River Adur CFMP - Appendix B (September 2008) 172 The balance of FRM agricultural land expenditure to AAD is caused by flooding will unacceptable with be minimised significant increases in The balance of FRM FRM expenditure to expenditure to AAD reduce AAD to will be acceptable with properties and increases in FRM agricultural land expenditure to reduce AAD to properties and agricultural land Policy option P6 Environmental Not applicable Not applicable Not preferred option – this Policy Option is not

considered feasible in Social this policy unit.

Economic

Key HIGH: High negative A policy has a ‘high negative’ effect where it could contribute to a social, economic or environmental objective in a significantly negative way. A ‘high negative’ effect could be: (i) a very large increase in current flood risk; (ii) very large projected increases in flood risk under future conditions, and/or; (iii) significant additional social, economic and/or environmental losses. MEDIUM: Medium negative A policy has a ‘medium negative’ effect where it could contribute to a social, economic or environmental objective in a negative way. A ‘medium negative’ effect could be: (i) an increase in current flood risk; (ii) a projected increase in flood risk under future conditions, and/or; (iii) social, economic and/or environmental losses. LOW: Low negative A policy has a ‘low negative’ effect where it could make a limited contribution to a social, economic or environment objective, but where the overall contribution would be negative. A ‘low negative’ effect could be: (i) an overall increase in current flood risk; (ii) an overall increase in flood risk under future conditions, and/or; (iii) overall social, economic and/or environmental losses. NEUTRAL: Neutral A policy has a ‘neutral’ effect where it makes neither a positive or negative contribution to a social, economic or environmental objective. A ‘neutral’ effect could be: (i) no change in current level of risk. In this instance the current level of risk would have to be low, so that the residual risk after a neutral policy was implemented remained acceptable; (ii) no change in flood risk under future conditions. In this instance projected future risk would need to be low so that the residual risk after a neutral policy was implemented remained acceptable, and/or; (iii) no additional social, economic and/or environmental gains or losses. Policy options may also be ‘neutral’ where they are not relevant in a particular policy unit, or where it is not feasible for a policy option to contribute to an objective. HIGH: High positive A policy has a ‘high positive’ effect where it could contribute to a social, Environment Agency River Adur CFMP - Appendix B (September 2008) 173 economic or environmental objective in a significantly positive way. A ‘high positive’ effect could be: (i) a very large reduction in current flood risk; (ii) avoiding/reducing very large projected increases in flood risk under future conditions, and/or; (iii) significant additional social, economic and/or environmental gains. MEDIUM: Medium positive A policy has a ‘medium positive’ effect where it could contribute to a social, economic or environmental objective in a positive way. A ‘medium positive’ effect could be: (i) a reduction in current flood risk; (ii) avoiding/reducing projected increases in flood risk under future conditions, and/or; (iii) additional social, economic and/or environmental gains. LOW: Low positive A policy has a ‘low positive’ effect where it could make a limited contribution to a social, economic or environment objective, but where the overall contribution would be positive. A ‘low positive’ effect could be: (i) an overall reduction in current flood risk; (ii) an overall avoidance/reduction in flood risk under future conditions,

Environment Agency River Adur CFMP - Appendix B (September 2008) 174

Form B8 Summary of preferred policy Policy unit 7 - Shoreham and Adur Estuary Physical characteristics: - This unit is predominantly urban including Shoreham and Lancing. - Includes part of River Adur corridor from the coast to the A27. - The A27 trunk road and chalk downland landscape forms the northern policy unit boundary. - Shoreham airport lies entirely within this unit. - Mainly chalk geology with flat low-lying ground. Flood mechanism: - Heavily tidally influenced. - Overtopping of embankments – will not generally overtop due to fluvial flooding on its own and will require significant tidal influence. - Surface water flooding through Shoreham airport generated from run-off from the steep slopes of the South Downs – can takes weeks for the flood water to subside. Receptor: - People, properties and infrastructure of the urban areas, including A259, A27, and Shoreham Airport. - Most of the Adur Estuary SSSI lies within this policy unit, although only a minor extent that is not channel lies within the 1% annual probability flood outline. - Currently approximately 11 properties are at risk of fluvial flooding in the policy unit Problem/risk from the 1% annual probability fluvial flood event. As a result of climate change the number of properties at risk of fluvial flood alone is not expected to increase significantly. However, if a fluvial event should be combined with a significant tidal influence, it is expected that a large number of properties (around 1750) will be at risk in the future with a potential of up to £15 million damages (AAD). Current Flood Risk Summary Number of properties at risk of flooding (1% annual probability flood event) 11 Total damages (approx.) (1% annual probability flood event) £0.4 million Annual averages damages (approx.) £80,000 Future Flood risk: - Flood risk from fluvial flooding is currently assessed as low, assessment changes to high in the future due to the increased influence from the tide resulting from sea level rise. - Flood risk from surface water flooding is currently assessed as low to medium, assessment remains low to medium in the future. Future Flood Risk Summary (in 100 years time) Number of properties at risk of flooding (1% annual probability flood event) 1757 Total damages (approx.) (1% annual probability flood event) £78 million Annual averages damages (approx.) £15 million Policy 4 - Take further action to sustain current scale of flood risk into the future (responding Policy selected to the potential increases in flood risk from urban development, land use change, and climate change). Although there are opportunities to reduce flooding in this unit by increasing storage on the floodplain upstream in other policy units, the level of potential flood risk in the unit is predicted to increase significantly (up to £15 million in damages AAD) in the future. Therefore we have selected policy 4 for this policy unit. Current management and maintenance activities include grass and weed cutting, cutting back overhanging branches, channel desilting and debris removal. This policy applies to this policy unit for the following reasons: - The current level of fluvial flood risk alone is low, however a combination of a high tide and high river flows does increase the level of flood risk. Justification - The level of flood risk in Shoreham needs to be addressed – local defences will need to be maintained and improved over time to mitigate the affects of climate change, and this is recognised in the Rivers Arun to Adur Coastal Defence strategy study. - The selected policy would help achieve the economic, and social objectives by maintaining the current level of flood risk within the policy unit in the future, by carrying out appropriate works to the river wall defences through the unit. - Protection to historic landfill area from flooding. - Supports the regeneration proposals for Shoreham (Shoreham Renaissance, Shoreham Marine North, Shoreham Airport and Shoreham Hospital). - Ensure flood damages do not significantly increase in Shoreham due to future change Catchment (urban development and climate change). objectives - Ensure that river channel and flood defence maintenance expenditure is appropriate to

Environment Agency River Adur CFMP - Appendix B (September 2008) 175 the property economic damage in urban areas from flooding. - Ensure the impact of flooding on people and property does not significantly increase in Shoreham in the future. - Ensure the disruption caused by flooding to transport and critical infrastructure does not increase in Shoreham in the future. - Protect and enhance the Adur Estuary SSSI. - Increase the landscape character value of the Sussex Downs. Opportunities: - Provide development control advice to ensure no increase in run-off from the new development proposed in the South East Plan (e.g. Shoreham). - Reduce flood risk and improve water quality by promoting and encourage the use of SuDS in the proposed urban developments in Shoreham. - Investigate removal of Environment Agency owned and maintained existing raised defences to reinstate the floodplain between Steyning and Shoreham to a naturally functioning state, to provide flood storage and enhance conservation value and biodiversity. - Potential for improving the current defences, for example possible installation of demountable or temporary defences in Shoreham and Burgess Hill. - Improvements in the efficiency of channel and flood defence maintenance processes. - Effective and efficient use of developer contributions for flood risk management. - To work with Defra and farmers to produce soil management plans which have a benefit to flood risk through reducing the run-off rate. - Continued practice and development of the Emergency Response Plan in Brighton and Hove, Worthing, Shoreham, and Burgess Hill. - Influence the coastal defence strategy, along the Lower Adur, Teville Stream and Ferring Rife, to improve the sustainability of flood risk management in the this area. - Reduce surface water run-off and soil erosion by supporting the existing and future management policies regarding environmentally sensitive farming practices. - Support the existing flood defence measures in relation to surface water flooding. Catchment-wide - Help meet national biodiversity action plan (BAP) targets. opportunities

and constraints Constraints: - Government and international legislation, environmental management policies, plans and strategies for the catchment must be complied with, such as accommodating new housing within the catchment as detailed by the South East Plan and compliance with the Habitats Directive. - Steep catchments of the South Downs result in rapid run-off and quick responses to rainfall events. - CFMP objectives and policies must complement those of the Shoreline Management Plan (SMP) that affects the CFMP area. - Available funding for the initial set up of new flood risk management schemes. - Older flood defence structures are likely to be more costly to maintain. - Limited available information on surface water and groundwater flood damages. - Visual impact of flood risk management activities within the proposed National Park or Areas of Outstanding Natural Beauty. - Transport links in the catchment are a vital part of the communication network regionally, nationally and internationally, in particular the railways connecting London to the south coast and connecting the coastal towns and cities, the A23, A24, A27, A259, A283 and A2032. - Some environmentally designated habitats are susceptible to changes in flood frequency, floodwater chemistry, groundwater levels and drainage system maintenance. - Changes to flood risk management can affect the landscape, its character and value as an amenity. Policy 1 – do nothing. If defences were permitted to fall into disrepair the annual average damages could increase to more than £20 million and significantly more than 4200 people would be at risk. This policy, therefore, could not be considered as an alternative.

Policy 2 – reduce current level of flood risk management. If the current flood risk management was reduced the annual average damages could increase to more than £17 Alternative million and substantially more than 4200 people would be at risk. This is considered policies unacceptable. considered

Policy 3 – maintain current level of flood risk management. As with policy 1, this policy would not recognise the need to maintain flood risk from heavily influenced tidal flood events in the future, which is considered unacceptable.

Policy 5 - reduce the level of flood risk, both now and in the future. The current level of risk is

Environment Agency River Adur CFMP - Appendix B (September 2008) 176 managed adequately and therefore this policy is not justified.

Policy 6 – increase flooding to reduce flood risk elsewhere. There are limited opportunities within this policy unit, due to the high density of development and essential infrastructure, to take this approach. Flood risk from the sea is a significant consideration in this policy unit. Therefore, fluvial flood risk management options must fit with the shoreline management plan policy and actions.

We have estimated the future increase in flood risk within this policy unit on the best available prediction we have of climate change (prior to the Defra October 2006 guidance), frequency and size of storms and flood events in the future. Although the Defra 2006 guidance suggests greater levels of sea rise in the future, than used in the broadscale modelling, this would not change the policy selected for this policy unit. Uncertainties

and The broadscale model has not included the drainage network through the Shoreham Airport dependencies site. This area is at risk from overtopping of the Adur and also from groundwater and surface water run-off. There is, therefore, some uncertainty in the resulting flood extent and severity – particularly in the long-term. We have taken this uncertainty into account when selecting the most appropriate policy, but we must look at this again at the next CFMP review.

Environment Agency River Adur CFMP - Appendix B (September 2008) 177 Form B9 Requirements for further policy development and appraisal Policy unit 7 – Shoreham and Adur Estuary Is there a need for further policy development? No If yes, then mark policy options for more detailed development. Some complex policies may require more detailed development, probably at Strategy Plan level. Is there a need for further more detailed appraisal? No If yes, take forward to strategy study.

Environment Agency River Adur CFMP - Appendix B (September 2008) 178

Form B10 Indicators for monitoring, review and evaluation This form sets out the indicators that need to be included in the policy implementation plan, for policy monitoring, drawing on the residual risks and likely impacts identified above. This will allow better review and evaluation of the policy when implemented. Policy unit 7 – Shoreham and Adur Estuary Indicators to be included in policy unit 7 implementation plan are:

Economic - Total annual average damages (to properties and agriculture) from fluvial flooding (£AAD). - Estimated damages resulting from surface water and groundwater flooding (£)(based on historical damages). - Balance of annual river channel and flood defence maintenance expenditure (£) to annual average damages from fluvial flooding to property (£).

Social - Number of people and properties affected by the 1% annual probability fluvial flood event. - The estimated number of properties affected by surface water and groundwater flooding (based on historical records). - Length of A road and railway line (km) affected by the 1% annual probability fluvial flood event. - Number of critical infrastructure sites affected by the 1% annual probability fluvial flood event. - Number and period of recorded A road and railway closures due to surface water and groundwater flooding (based on historical records). - Number of critical infrastructure sites recorded as being affected by surface water and groundwater flooding (based on historical records).

Environmental - Habitat quality and species diversity. - Landscape character assessment of the AONB.

Environment Agency River Adur CFMP - Appendix B (September 2008) 179

Policy unit 8 Adur Valley (north of A27 to south of Steyning) Policy appraisal forms Form B5 – Summary of current and future levels of and responses to flood risk. Form B6 – Appraisal of policy options against policy unit objectives. Form B7 – Summary of losses and gains. Form B8 – Summary of preferred policy. Form B9 – Requirements for further policy development and appraisal. Form B10 – Indicators for monitoring, review and evaluation.

Environment Agency River Adur CFMP - Appendix B (September 2008) 180

Form B5 Summary of current and future levels or and responses to flood risk Policy unit 8 – Adur Valley (north of A27 to south of Steyning) Defences: In this unit raised embankments extend on both banks, giving a total of 10 km of defences along this reach of the River Adur.

Flood Warning: This policy unit covered by the River Adur from downstream of Upper Beeding to Norfolk Bridge at Shoreham Flood Warning Area. Less than Current responses to flood risk five properties are connected to the flood warnings direct service. within the policy unit

Maintenance: We currently carry out annual inspection and maintenance of the embankments and flap gates. The estimated cost of maintaining the channels and existing defences under the Environment Agency’s responsibility is approximately £75,000. Standard of protection: The River Adur embankments are considered to offer Standards of service that apply protection ranging from the 3.33% annual probability fluvial flood event (1 in 30) to flood defences within the to the 0.5% annual probability event (1 in 200). They are considered to be at or policy unit above the target condition. In 10% flood In 1% flood In 0.1% flood Receptors outline* outline* outline* Residential properties 0 0 N/A Commercial properties 0 0 N/A Population 0 0 N/A Property damages 0 0 N/A Agricultural damages £25 £26,835 N/A A roads 0 km 0.34 km 2.1 km Railways 0 km 0 km 0 km Agricultural land Grade 1 0 km2 0 km2 0 km2 Agricultural land Grade 2 0 km2 0 km2 0 km2 What is currently exposed to Agricultural land Grade 3 <0.001 km2 0.89 km2 1.86 km2 flooding? Agricultural land Grade 4 0 km2 0.39 km2 0.82 km2 Agricultural land Grade 5 0 km2 0 km2 0 km2 SNCIs 0 km2 0 km2 0.17 km2 SSSI 0 km2 0 km2 0.11 km2 Listed Buildings 0 0 0 SM 0 0 0 AONB 0.001 km2 1.28 km2 2.68 km2 ESA 0.001 km2 1.23 km2 2.67 km2 Registered Historic Parks and 2 2 2 Gardens 0 km 0 km 0 km Proposed National Park 0.001 km2 1.28 km2 2.63 km2 * 10% and 1% based on broadscale model results and 0.1% based on Flood Zone 2 Economic and social receptors: There are no people or properties at risk of flooding for the 1% annual probability flood event.

A short length, less than 0.5km, of the A283 is located within the 1% and 0.1% annual probability flood event outline.

Less than 1km2 of agricultural land of grade 3 or 4 is at risk of flooding for the 1% annual probability flood event, increasing slightly for the 0.1% annual probability flood event. Who and what are currently most vulnerable to flood Environmental designation: damage and losses? There are no internationally or nationally designated sites, SSSIs or SNCIs at risk of flooding for the 1% annual probability flood event within this policy unit. A small extent of the Adur Estuary SSSI and River Adur Meadows, Shoreham-by- Sea and the Mill Hill, Shoreham-by-Sea SNCIs are within the 0.1% annual probability flood event outline.

Landscape: Parts of the Sussex Downs AONB and South Downs ESA and proposed National Park lies within both the 1% and 0.1% annual probability flood event outlines.

Natural and Historic Environment: Environment Agency River Adur CFMP - Appendix B (September 2008) 181 There are no listed buildings, registered historic parks and gardens, SMs or wet woodlands at risk of flooding for the 1% or 0.1% annual probability flood events. Increase in frequency of storm events resulting more frequent fluvial flooding. Sea level rise increases the likelihood of tidally influenced flooding in this policy unit*.

What are the key factors that *To represent future sea level rise, the tidal boundary within the broadscale model was scaled to could drive future flood risk? increase the maximum still water level by 600mm for the 100 year timescale. These climate change figures used were the accepted approach for ‘typical’ catchments when the scoping stage broadscale modelling was carried out. Since the scoping stage was completed new Defra guidance (October 2006) on climate change has been released which suggest that for a 100 year time scale, sea level may rise by almost 1m. Therefore the results from the broadscale model in the tidally influenced areas are likely to have under predicted the increase in flood risk and damages in the future. There is a very small increase (approximately £0.04 million) in AAD due to What are the possible future climate change over the next 100 years. levels of flood risk under the

main scenarios? In 100 years approximately 1 property is at risk of flooding. What potential responses (or There is potential to reduce flood risk downstream in other policy units by groups of responses) are providing flood storage within this policy unit. Lowering or removing flood being considered to manage defences could help reduce flood risk in this and other policy units as well flood risk? providing beneficial environmental impact. Flood risk from the sea should also be a consideration in this policy unit due to the effect of sea level rise. Therefore, fluvial flood risk management options must consider the effects of shoreline management plan policy and actions.

What gaps and uncertainties We have estimated the future increase in flood risk within this policy unit on the are there in knowledge, and best available prediction we have of climate change (prior to the Defra October what assumptions have been 2006 guidance), frequency and size of storms and flood events in the future. made? The broadscale modelling has shown that lowering or removing flood defences can help reduce flood risk in neighbouring policy units. We will need more detailed studies to find out if it is practical to do this and improve the environment at the same time.

Generic response: Rural land use change – changing farming practices to reduce run-off rates 1% annual probability fluvial flood Results from broadscale modelling damages (£m) The broadscale modelling has indicated that a change in the way land is managed, in the upper parts of the CFMP area, has a large positive impact on Future basecase = £0.065 flood damages within this policy unit. Flood damages are shown to decrease Generic response = £0.027 by 58% for the 1% annual probability fluvial flood event, with flood depths decreasing by approximately 0.5 to 1m. % change = -58% Conclusions The reduction in run-off rates by changes in farming practices in the upper parts of the catchment has shown a significant reduction in flood damages in this policy unit.

Environment Agency River Adur CFMP - Appendix B (September 2008) 182 Generic response: Attenuation/retention (storage) on the Adur West Branch 1% annual probability fluvial flood Results from broadscale modelling damages (£m)

There is a clear reduction in flood damages in the policy units further Future basecase = £0.065 upstream, but there is only a small effect in this policy unit with a 3% decrease Generic response = £0.063 in flood damages. % change = -3% Conclusions The flood mechanisms in this policy unit are dominated by tidal influences. Flood attenuation in the upper parts of the Adur catchment has limited impact on flood depths or extent within this policy unit.

Generic response: Barrier across the River Adur at Shoreham 1% annual probability fluvial flood Results from broadscale modelling damages (£m) This case looks at the situation where a barrier is built across the mouth of the river that keeps the tide out, but allows free discharge of the river into the sea Future basecase = £0.065 at low tide. There is a very small positive effect from this option in this policy Generic response = £0.064 unit with a 3% reduction in flood damages for the 1% annual probability fluvial flood event. % change = -2% Conclusions There are limited impacts from flooding in this policy unit with less than 5 properties affected by the more severe fluvial flood events, which is reflected in the low flood damages.

However, the environmental benefits from the increased flood extent should be investigated further.

Generic response: Reducing the height of all raised embankments along the River Adur 1% annual probability fluvial flood Results from broadscale modelling damages (£m) Reducing the height of the raised embankments along the River Adur allows more frequent inundation of the floodplain on both sides of the river. The Future basecase = £0.065 results from the broadscale modelling show a large reduction of 31% for a 1% Generic response = £0.045 annual probability fluvial flood event. Within this policy unit water depths are reduced by approximately 1m from the future basecase. % change = -31% Conclusions The impact of lowering the embankments along the River Adur within this policy unit increases the flood extent as it allows the water to spread out over a larger floodplain area, which has the effect of lowering the water depths and thus reducing the flood damages.

Environment Agency River Adur CFMP - Appendix B (September 2008) 183 Form B6 Appraisal of policy options against policy unit objectives Policy unit 8 – Adur Valley (north of A27 to south of Steyning) KEY = Scale of policy impact on objective: Not appraised Baseline Meets objective No impact Doesn’t meet object Uncertain The preferred policy option is indicated below by the policy option highlighted in pink Baseline (current Policy 1 Policy 2 Policy 3 Policy 4 Policy 5 Policy 6 and future) No maintenance of watercourses. Channels become blocked with vegetation and Reduction in conveyance is maintenance of Improved level of reduced. watercourses. channel maintenance Maintenance of the of watercourses. Channels become There is potential to Current and future The height of raised channels continues. blocked with vegetation Construct a barrier increase water baseline with current embankments would and conveyance is across the River Adur retention by flood risk reduce over time. The flood warning Localised protection reduced. within this policy unit. introducing flood management. service remains in measures introduced. storage areas. The flood warning place. The flood warning service is withdrawn. service remains in The flood warning

place. service is improved. A do nothing approach would increase the flooding Catchment Targets and Opportunities and in an unmanaged and objectives Indicators Constraints unpredictable way. Economic objectives Opportunities - Provide development control advice to ensure no increase in run-off from the new development proposed in the South East Plan - Reduce flood risk and improve water quality by promoting and encourage the use of SuDS in the proposed urban developments. Targets - Investigate removal of No maintenance of No significant increase Environment Agency owned Improved channel channels and a in damages along the and maintained existing The current total As channels decrease maintenance and Increasing water raised defences to reinstate reduction in height of The total annual The construction of a Lower Adur corridor due annual average in capacity due to localised protection retention by the floodplain between embankments would average damages barrier across the Ensure flood damages to future changes Steyning and Shoreham to a damages from fluvial reduced maintenance measures will mitigate introducing specific lead to a significant from fluvial flooding River Adur would do not significantly (climate change). naturally functioning state, to flooding are the total annual the affects of climate flood storage areas in provide flood storage and increase in flooding will increase over time reduce total annual increase along the approximately £450. average damages from change. The total this policy unit should enhance conservation value with total annual due to the affects of average damages Lower Adur corridor. Indicators and biodiversity. This increases to fluvial flooding will annual average reduce flood damages average damages climate change to be from fluvial flooding Total annual average Constraints around £1,000 in the increase to be more damages from fluvial from fluvial flooding to - Government and international from fluvial flooding around £1,000. to be minimal. damages (to properties future. than £1,000. flooding will remain at be minimal. legislation, environmental being significantly and agriculture) from approximately £450. management policies, plans more than £1,000. fluvial flooding (£AAD). and strategies for the catchment must be complied with, such as accommodating new housing within the catchment as detailed by the South East Plan and compliance with the Habitats Directive. - Steep catchments of the South Downs result in rapid run-off and quick responses to rainfall events. Social objectives

Environment Agency River Adur CFMP - Appendix B (September 2008) 184 Ensure the impact of Targets Opportunities - Investigate removal of flooding on people No significant increase Environment Agency owned and property does not in the number of people and maintained existing significantly increase or properties affected by raised defences to reinstate the 1% annual the floodplain between in the future (for Partridge Green and probability fluvial flood Steyning and between No maintenance of example due to event or surface water Steyning and Shoreham to a channels and climate change). flooding in the future naturally functioning state, to drainage networks provide flood storage and enhance conservation value would result in an Indicators Approximately 0 and biodiversity. increase in the Number of people and - Influence the coastal defence people and 0 The increased frequency, extent and It is likely that the No people and properties affected by strategy, along the Lower properties are at risk No people and frequency of flooding Adur, Teville Stream and depth of localised number of people and No people and properties are likely the 1% annual of localised fluvial properties are likely to will be managed such Ferring Rife, to improve the fluvial flooding. properties at risk of properties are likely to to be at risk of probability fluvial flood sustainability of flood risk flooding by the current be at risk of localised that the number of localise fluvial flooding be at risk of localised localised fluvial event management in the this area. 1% annual probability fluvial flooding by the properties at risk in The number of may increase to be fluvial flooding by the flooding by the 1% Constraints flood event. This is 1% annual probability this policy unit is not - Government and international people and properties more than zero. 1% annual probability annual probability Coverage of Flood not anticipated to flood event increased from the legislation, environmental at risk of localise flood event flood event Warning Service management policies, plans increase the future. current baseline and flooding will increase There is no flood and strategies for the There is no flood there remains no to be more than 23 warning service Flood Warning Service There is no flood catchment must be complied There are currently no warning service requirement for a with, such as accommodating and 10 respectively. available, which may is introduced. warning service properties covered by available. Flood Warning new housing within the result in increased risk available. catchment as detailed by the a flood warning Service. There will be no flood to human life. South East Plan and service. compliance with the Habitats warning system Directive. which may result in - Visual impact of flood risk management activities within increased risk to the proposed National Park human life. or Areas of Outstanding Natural Beauty. - CFMP objectives and policies must complement those of the Shoreline Management Plan (SMP) that affects the CFMP area. Environmental objectives

Environment Agency River Adur CFMP - Appendix B (September 2008) 185 Opportunities - Enhance the character of the landscape and increase amenity opportunities for recreation, tourism and leisure activities. - Move toward more natural rivers and drainage networks, as outlined within PPS25, will mean we can achieve more efficient and sustainable water management, whilst enhancing landscape character. - Investigate removal of Environment Agency owned and maintained existing Restoring the rivers to raised defences to reinstate a naturally functioning the floodplain between Currently there is state and increasing Steyning and Shoreham to a naturally functioning state, to approximately 9.4km floodplain connectivity provide flood storage and of defended No maintenance and could be achieved enhance conservation value watercourse and no removing the through this policy and biodiversity. embankments would option whilst providing Targets - Help meet national naturally functioning A reduction in Increase the length of river or naturally active allow the channel and maintenance would The construction of a flood storage. biodiversity action plan (BAP) It is not expected that naturally functioning targets. floodplain in this policy floodplain to function allow the channel and barrier across the the river processes or There is unlikely to be river and area of Constraints unit. There are more naturally and floodplain to function River Adur will The length of naturally - Government and international floodplain connectivity any significant naturally active opportunities now and restore the natural more naturally and reduce the natural functioning river is legislation, environmental will significantly alterations to the river floodplain along the management policies, plans in the future to river processes (i.e. restore the natural river river processes and likely to increase by change under this processes and Restore parts of the River Adur downstream and strategies for the enhance the floodplain erosion and processes (i.e. erosion floodplain up to 9.4km and the policy option. floodplain connectivity River Adur and of Steyning and Upper catchment must be complied connectivity along deposition). and deposition). connectivity. area of naturally active with, such as accommodating under this policy floodplain to a naturally Beeding where feasible, new housing within the defended parts of the However, this would However, this would floodplain to up to With current flood risk option. 2 functioning state where providing suitable quality catchment as detailed by the River Adur, for occur in an occur in an unmanaged However, given that 2.6km . management in the feasible downstream of habitat. South East Plan and example by restoring it unmanaged and and unpredictable way. there is no current compliance with the Habitats future the length of The length of naturally Steyning and Upper back to its original unpredictable way. extent of naturally This would be Directive. naturally functioning functioning river and Beeding. Indicators - Some environmentally state or removing The length of naturally functioning river or achieved in a river and naturally naturally active Length of naturally designated habitats are raised embankments. The length of functioning river is naturally active managed and active floodplain is not floodplain is likely to functioning river (km). susceptible to changes in naturally functioning likely to increase by floodplain this policy controlled way. These flood frequency, floodwater expected to notably remain at the current With current flood risk river is likely to around 4 km and the option is unlikely to flood risk chemistry, groundwater alter with the affects of level. Area of naturally levels and drainage system management in the increase by around 9 area of naturally active notable impact on the management climate change. functioning floodplain maintenance. future the length of km and the area of floodplain to around 1 current situation. practices would have 2 - Individual homes and 2 (km ). properties are currently at naturally functioning naturally active km . the potential benefit of risk of flooding. river and naturally floodplain to reducing the flood risk - Presence of protected active floodplain is not approximately 2 km2. in other parts of this species with specific water policy unit and in level, water quality and expected to notably habitat requirements, for alter. policy 7 (Shoreham example in the Adur Estuary and Adur Estuary) SSSI. downstream. - Changes to flood risk management can affect the landscape, its character and value as an amenity. - Historic development and some heritage designations in Steyning, Bramber and Upper Beeding present permanent physical obstructions. - Location of electricity pylons adjacent to the Lower River Adur (currently protected by existing defences). - No degradation of existing fish passage and habitat.

Environment Agency River Adur CFMP - Appendix B (September 2008) 186 The construction of a The area of the barrier across the Sussex Downs River Adur will Opportunities There is currently - Help meet national AONB and South reduce frequency and biodiversity action plan (BAP) approximately The area of the 2 Downs ESA and The area of the Sussex depth of flooding and targets. 1.28km of the Sussex Sussex Downs AONB The area of the Sussex proposed National Downs AONB and therefore have a - Investigate removal of Downs AONB and and South Downs Downs AONB and The landscape Environment Agency owned Park located within South Downs ESA and negative impact on Targets South Downs ESA ESA and proposed South Downs ESA and character of the and maintained existing the 1% annual proposed National Park the landscape Increase the landscape and proposed National National Park located proposed National Park Sussex Downs AONB raised defences to reinstate probability flood located within the 1% character of the character value of the the floodplain between Park located within the within the 1% annual located within the 1% and South Downs event outline annual probability flood Sussex Downs Sussex Downs AONB Steyning and Shoreham to a 1% annual probability probability flood event annual probability flood ESA and proposed Increase the landscape naturally functioning state, to increases to be more event outline increases AONB and South and South Downs ESA provide flood storage and flood event outline. 2 2 outline increases over event outline remains National Park can be character value of the than 2.6 km . to be more than 2 km . 2 Downs ESA and and proposed National enhance conservation value This increases by a time to at around 2 at around 1.28km . enhanced with the Sussex Downs AONB 2 proposed National Park. and biodiversity. minor extent to around km . implementation of and South Downs ESA Constraints 2 The landscape The landscape Park. 2 km in the future. There would be no considered flood risk and proposed National - Some environmentally character of the character of the Indicators There would be no impact on the management Park. designated habitats are Sussex Downs Sussex Downs AONB The area of the Landscape character susceptible to changes in The landscape notable impact on the landscape character of practices, such as AONB and South and South Downs ESA Sussex Downs assessment of the flood frequency, floodwater character of the landscape character the Sussex Downs increasing the flood chemistry, groundwater Downs ESA and and proposed National AONB and South AONB, ESA and Sussex Downs AONB of the Sussex Downs AONB and South storage areas, in a levels and drainage system proposed National Park is likely to alter in Downs ESA and proposed National Park. maintenance. and South Downs AONB and South Downs ESA and managed and Park is likely to alter a beneficial manner, proposed National - Changes to flood risk ESA and proposed Downs ESA and proposed National Park controlled way. management can affect the in a beneficial however, it will occur in Park located within National Park is proposed National in this policy unit. landscape, it’s character and manner, however, it an unmanaged way. the 1% annual unlikely to notable Park in this policy unit. value as an amenity. will occur in an probability flood alter. unmanaged and un event outline controlled way. decreases to be minimal. Does this policy change flood risk locally or elsewhere: Impact uncertain - Impact uncertain - Unlikely to increased water Unlikely to Unlikely to Increased water increased water significantly affect retention will significantly affect significantly affect retention will benefit retention will benefit adjacent policy benefit adjacent policy units adjacent policy units downstream areas downstream areas units downstream areas

Environment Agency River Adur CFMP - Appendix B (September 2008) 187 Form B7 – Summary of losses and gains.

Policy unit Policy Unit 8 - Adur Valley (north of A27 to south of Steyning name/number:

Preferred policy Policy options Losses Gains option relative to current baseline Policy option P1 Environmental NO LOSSES HIGH+ Not preferred option – Although the benefits to The length of naturally the environment are functioning river and potentially high, area of naturally alterations to the functioning floodplain function of rivers and will increase by floodplains and to the approximately 9km 2 landscape will be and 2km respectively, unmanaged and but in an unmanaged uncontrolled and and unpredictable way therefore unpredictable. The areas of the In addition to this, the Sussex Downs AONB AAD to properties and and South Downs agricultural land ESA/proposed NP that resulting from this policy fall within the 1% AEP will be unacceptably flood outline will high. increase by more than 0.72km2 and are likely

to be beneficially altered but in an unmanaged and

uncontrolled way

Social MEDIUM- NO GAINS

The number of people and property at risk

significantly increases

Economic HIGH- NO GAINS

AAD to properties and agricultural land will increase by more than 550 Policy option P2 Environmental NO LOSSES MEDIUM+ Not preferred option – Although the benefits to The length of naturally the environment are functioning river and potentially high, area of naturally alterations to the functioning floodplain landscape and river and will increase by floodplain function will approximately 4km 2 be unmanaged and and 1km respectively, therefore unpredictable. but in an unmanaged In addition to this, the and unpredictable way AAD to properties and The areas of the Environment Agency River Adur CFMP - Appendix B (September 2008) 188 Sussex Downs AONB agricultural land and South Downs resulting from this policy

ESA/proposed NP that will be unacceptably fall within the 1% AEP high. flood outline will

increase by more than 0.72km2 and are likely to be beneficially

altered but in an unmanaged way

Social LOW- NO GAINS

The number of people and property at risk

significantly increases

Economic HIGH- NO GAINS

AAD to properties and agricultural land will increase by more than 550 Policy option P3 Environmental NO LOSSES LOW+ Not preferred option – The potential benefits in The areas of the terms of the Sussex Downs AONB environment are not and South Downs sufficiently optimised ESA/proposed NP that under this policy. In fall within the 1% AEP addition to this, the AAD will increase by 2 to properties and approximately 0.72km agricultural land will but with no notable increase significantly in increase in landscape the future. value

NEUTRAL=

The length of naturally

functioning river and area of naturally functioning floodplain

will not increase notably in the future

Social NO LOSSES NO GAINS

Economic MEDIUM- NO GAINS

AAD to properties and agricultural land will increase by approximately 550 Policy option P4 Environmental LOW- NEUTRAL= Not preferred option – Although AAD to The areas of the Sussex The length of naturally properties and Environment Agency River Adur CFMP - Appendix B (September 2008) 189 Downs AONB and South functioning river and agricultural land will not Downs ESA/proposed area of naturally increase in the future,

NP that fall within the functioning floodplain opportunities to bring 1% AEP remain the will not increase benefits to the same with no increase in notably in the future environment are not

landscape value sufficiently optimised under this policy.

Social NO LOSSES NO GAINS

Economic NO LOSSES HIGH+

AAD to properties and agricultural land will not increase in the future Policy option P5 Environmental MEDIUM- NO GAINS Not preferred option – Although AAD will be The areas of the Sussex minimised, the impact Downs AONB and South on the environment is Downs ESA/proposed unnecessarily negative. NP that fall within the 1% AEP will be

decreased which will impact negatively on the landscape value

NEUTRAL=

The length of naturally functioning river and area of naturally

functioning floodplain will not increase in the future

Social NO LOSSES NO GAINS

Economic NO LOSSES HIGH+

AAD to properties and agricultural land will be minimised Policy option P6 Environmental NO LOSSES HIGH+ Preferred Policy Option – There are no losses The length of naturally under this policy option. functioning river and The potential benefits to area of naturally river and landscape functioning floodplain function and landscape will increase by up to 2 value are maximised 9km and 2km and will be carried out in respectively, but in an a managed and managed and controlled way. controlled way Encouraging increased The landscape value uptake of agri- of the Sussex Downs environment schemes AONB and South and managing FRM will Environment Agency River Adur CFMP - Appendix B (September 2008) 190 Downs ESA/proposed minimise the AAD to NP will be enhanced in land. Implementing

a managed and policy option 6 in this controlled way part of the catchment will also bring strategic

benefits to policy units NO GAINS Social NO LOSSES downstream through increased floodwater

storage. HIGH+ Economic NO LOSSES AAD to properties and agricultural land will not be minimised

Key HIGH: High negative A policy has a ‘high negative’ effect where it could contribute to a social, economic or environmental objective in a significantly negative way. A ‘high negative’ effect could be: (i) a very large increase in current flood risk; (ii) very large projected increases in flood risk under future conditions, and/or; (iii) significant additional social, economic and/or environmental losses. MEDIUM: Medium negative A policy has a ‘medium negative’ effect where it could contribute to a social, economic or environmental objective in a negative way. A ‘medium negative’ effect could be: (i) an increase in current flood risk; (ii) a projected increase in flood risk under future conditions, and/or; (iii) social, economic and/or environmental losses. LOW: Low negative A policy has a ‘low negative’ effect where it could make a limited contribution to a social, economic or environment objective, but where the overall contribution would be negative. A ‘low negative’ effect could be: (i) an overall increase in current flood risk; (ii) an overall increase in flood risk under future conditions, and/or; (iii) overall social, economic and/or environmental losses. NEUTRAL: Neutral A policy has a ‘neutral’ effect where it makes neither a positive or negative contribution to a social, economic or environmental objective. A ‘neutral’ effect could be: (i) no change in current level of risk. In this instance the current level of risk would have to be low, so that the residual risk after a neutral policy was implemented remained acceptable; (ii) no change in flood risk under future conditions. In this instance projected future risk would need to be low so that the residual risk after a neutral policy was implemented remained acceptable, and/or; (iii) no additional social, economic and/or environmental gains or losses. Policy options may also be ‘neutral’ where they are not relevant in a particular policy unit, or where it is not feasible for a policy option to contribute to an objective. HIGH: High positive A policy has a ‘high positive’ effect where it could contribute to a social, economic or environmental objective in a significantly positive way. A ‘high positive’ effect could be: (i) a very large reduction in current flood risk; (ii) avoiding/reducing very large projected increases in flood risk under future conditions, and/or; (iii) significant additional social, economic and/or environmental gains. Environment Agency River Adur CFMP - Appendix B (September 2008) 191 MEDIUM: Medium positive A policy has a ‘medium positive’ effect where it could contribute to a social, economic or environmental objective in a positive way. A ‘medium positive’ effect could be: (i) a reduction in current flood risk; (ii) avoiding/reducing projected increases in flood risk under future conditions, and/or; (iii) additional social, economic and/or environmental gains. LOW: Low positive A policy has a ‘low positive’ effect where it could make a limited contribution to a social, economic or environment objective, but where the overall contribution would be positive. A ‘low positive’ effect could be: (i) an overall reduction in current flood risk; (ii) an overall avoidance/reduction in flood risk under future conditions,

Environment Agency River Adur CFMP - Appendix B (September 2008) 192

Form B8 Summary of preferred policy Policy unit 8 – Adur Valley (north of A27 to south of Steyning) Physical characteristics: - Unit consists of the rural landscape immediately adjacent to the river corridor and contains a few isolated properties. - River Adur corridor, including a small part of the Adur Estuary SSSI. - Relatively flat low-lying ground in a valley between the South Downs Chalk block. Flood mechanism: - Heavily influenced tidal flooding. - Overtopping of embankments – will not generally overtop due to fluvial flooding on its own and will require significant tidal influence. Receptor: - Infrastructure (roads and rail), isolated properties and agricultural land. - Sussex Downs AONB, South Downs ESA and Proposed National Park. - Includes part of the Adur Estuary SSSI and part of the Beeding Hill and Newtimber Hill SSSI. No extent of these SSSIs are located within the 1% annual probability flood outline. Problem/risk - The majority of the River Adur Meadows, Shoreham-by-Sea, the Mill Hill, Shoreham-by-Sea and the Old Erringham Farm valley and road cutting SNCIs. No extent of these SNCIs are located within the 1% annual probability flood outline. - Currently no properties are at risk of fluvial flooding in the policy unit from the 1% annual probability fluvial flood event. Current Flood Risk Summary Number of properties at risk of flooding (1% annual probability flood event) 0 Total damages (approx.) (1% annual probability flood event) £27,000 Annual averages damages (approx.) £450 Future Flood risk: - Flood risk is currently assessed as low, and it is not expected to increase under future scenarios. Future Flood Risk Summary (in 100 years time) Number of properties at risk of flooding (1% annual probability flood event) Less than 5 Total damages (approx.) (1% annual probability flood event) £65,000 Annual averages damages (approx.) £1,000 Policy 6 - Take action to increase the frequency of flooding to deliver benefits locally or Policy selected elsewhere, which may constitute an overall flood risk reduction (for example for habitat inundation). This policy can deliver benefits for people and the environment locally or in other policy units. By increasing flooding locally in this unit, flooding downstream can be reduced, and in many instances, increasing flooding can improve wetland biodiversity, as flooding is a natural part of floodplain ecosystems. Current management and maintenance activities include grass and weed cutting, cutting back overhanging branches, channel desilting and debris removal. Policy 6 sets a framework that actively supports increased flooding, or at least keeps water on the land for longer. This applies to this policy unit for the following reasons: - With a low flood risk within this policy unit, there is no need for a significant flood risk reduction policy. - Applying policy 6 here may help reduce flood risk downstream in policy unit 7. Justification - An increase in flooding could result in an increase of approximately 140 hectares of wetland around the River Adur Meadows, Shoreham-by-Sea and the Mill Hill, Shoreham- by-Sea SNCIs. This will improve local biodiversity and help meet biodiversity action plan targets. - This policy would help meet the catchment objectives, having a positive effect on biodiversity in this area, leading to an eventual increase in extent, quality and diversity of wetland habitats, with opportunities for recreation and landscape. Emphasis would be placed on helping the public and landowners to understand the risk of flooding and climate change better; encourage close partnership with local communities and rural development authorities; and build policy objectives into planning documents. - Ensure flood damages do not significantly increase along the Lower Adur corridor. - Restore parts of the River Adur and floodplain to a naturally functioning state where Catchment feasible downstream of Steyning and Upper Beeding. objectives - Increase the landscape character value of the Sussex Downs AONB and South Downs ESA and proposed National Park. Catchment-wide Opportunities: opportunities - Provide development control advice to ensure no increase in run-off from the new

Environment Agency River Adur CFMP - Appendix B (September 2008) 193 and constraints development proposed in the South East Plan. - Reduce flood risk and improve water quality by promoting and encourage the use of SuDS in the proposed urban developments. - Investigate removal of Environment Agency owned and maintained existing raised defences to reinstate the floodplain between Steyning and Shoreham to a naturally functioning state, to provide flood storage, enhance conservation value and biodiversity. - Enhance the character of the landscape and increase amenity opportunities for recreation, tourism and leisure activities. - Move toward more natural rivers and drainage networks, as outlined within PPS25, will mean we can achieve more efficient and sustainable water management, whilst enhancing landscape character. - Help meet national biodiversity action plan (BAP) targets. Constraints: - Government and international legislation, environmental management policies, plans and strategies for the catchment must be complied with, such as accommodating new housing within the catchment as detailed by the South East Plan and compliance with the Habitats Directive. - Steep catchments of the South Downs result in rapid run-off and quick responses to rainfall events. - Some environmentally designated habitats are susceptible to changes in flood frequency, floodwater chemistry, groundwater levels and drainage system maintenance. - Individual homes and properties are currently at risk of flooding. - Presence of protected species with specific water level, water quality and habitat requirements, for example in the Adur Estuary SSSI. - Changes to flood risk management can affect the landscape, its character and value as an amenity. - Historic development and some heritage designations in Steyning, Bramber and Upper Beeding present permanent physical obstructions. - Location of electricity pylons adjacent to the Lower River Adur (currently protected by existing defences). - No degradation of existing fish passage and habitat. Policy 1 - do nothing. Although this could be considered as a possible policy option, and would have a similar long-term result as policy 6, the effects would happen in an unmanaged and unpredictable way, and local flood risk may increase.

Policy 2 - reduce current level of flood risk management. This could also be considered a possible policy option for this area, and it could allow increased floodplain inundation whilst controlling the changes that would happen in time. However, this policy does not reflect the scale of the likely changes and it does not ensure the level of investment and commitment to meet the catchment objectives.

Alternative Policy 3 - maintain current level of flood risk management. This option results in the least policies favourable result, with increases in damages locally of approximately 68% but with none of considered the benefits that would come from a managed approach of potentially increasing areas of wetland and therefore improving local biodiversity and help meet biodiversity action plan targets.

Policy 5 - reduce the level of flood risk, both now and in the future. This policy is not justified by the current and future level of flood risk within the policy unit, and would require an unsustainable level of investment in flood defences to meet future changes. Flood risk from the sea should also be a consideration in this policy unit due to the effect of sea level rise. Therefore, fluvial flood risk management options must consider the effects of shoreline management plan policy and actions.

We have estimated the future increase in flood risk within this policy unit on the best available Uncertainties prediction we have of climate change (prior to the Defra October 2006 guidance), frequency and and size of storms and flood events in the future. Although the Defra 2006 guidance suggests dependencies greater levels of sea rise in the future, than used in the broadscale modelling, this would not change the policy selected for this policy unit.

The broadscale modelling has shown that lowering or removing flood defences can help reduce flood risk in neighbouring policy units. We will need more detailed studies to find out if it is practical to do this and improve the environment at the same time.

Environment Agency River Adur CFMP - Appendix B (September 2008) 194 Form B9 Requirements for further policy development and appraisal Policy unit 8 – Adur Valley (north of A27 to south of Steyning) Is there a need for further policy development? No If yes, then mark policy options for more detailed development. Some complex policies may require more detailed development, probably at Strategy Plan level. Is there a need for further more detailed appraisal? Yes If yes, take forward to strategy study.

Environment Agency River Adur CFMP - Appendix B (September 2008) 195

Form B10 Indicators for monitoring, review and evaluation This form sets out the indicators that need to be included in the policy implementation plan, for policy monitoring, drawing on the residual risks and likely impacts identified above. This will allow better review and evaluation of the policy when implemented. Policy unit 8 – Adur Valley (north of A27 to south of Steyning) Indicators to be included in policy unit 8 implementation plan are:

Economic - Total annual average damages (to properties and agriculture) from fluvial flooding (£AAD).

Environmental - Length of naturally functioning river (km). - Area of naturally functioning floodplain (km2). - Landscape character assessment of the AONB, ESA and proposed National Park.

Environment Agency River Adur CFMP - Appendix B (September 2008) 196

Policy unit 9 South Downs (East) Policy appraisal forms Form B5 – Summary of current and future levels of and responses to flood risk. Form B6 – Appraisal of policy options against policy unit objectives. Form B7 – Summary of losses and gains. Form B8 – Summary of preferred policy. Form B9 – Requirements for further policy development and appraisal. Form B10 – Indicators for monitoring, review and evaluation.

Environment Agency River Adur CFMP - Appendix B (September 2008) 197

Form B5 Summary of current and future levels or and responses to flood risk Policy unit 9 – South Downs (East) Defences: There are no formal flood defences in this policy unit, however, there are small flood detention bunds at Bevendean to hold back localised run-off from the Downs.

Current responses to flood risk Flood warning: This policy unit is not covered by a fluvial flood warning area. within the policy unit No properties are connected to the flood warnings direct service.

Maintenance: The maintenance of these structures is unknown. The estimated annual cost of maintenance to channels undertaken by the Environment Agency within this policy unit is approximately £1,000. Standards of service that apply Standard of protection: There are no formal flood defences within this policy to flood defences within the unit. policy unit In 10% flood In 1% flood In 0.1% flood Receptors outline* outline* outline* Residential properties 0 0 N/A Commercial properties 0 0 N/A Population 0 0 N/A Property damages 0 0 N/A Agricultural damages £0 £0 N/A A roads 0 km 0 km 0 km Railways 0 km 0 km 0 km Agricultural land Grade 1 0 km2 0 km2 0 km2 Agricultural land Grade 2 0 km2 0 km2 0 km2 2 2 2 What is currently exposed to Agricultural land Grade 3 0 km 0 km 0.01 km flooding? Agricultural land Grade 4 0 km2 0 km2 0 km2 Agricultural land Grade 5 0 km2 0 km2 0 km2 SNCIs 0 km2 0 km2 0 km2 SSSI 0 km2 0 km2 0 km2 Listed Buildings 0 0 0 SM 0 0 0 AONB 0 km2 0 km2 0.01 km2 ESA 0 km2 0 km2 0 km2

Registered Historic Parks and 2 2 2 Gardens 0 km 0 km 0 km Proposed National Park 0 km2 0 km2 0.01 km2 * 10% and 1% based on broadscale model results and 0.1% based on Flood Zone 2 Economic and social receptors: There are no people, properties, extent of A road, railway or area of graded agricultural land at risk of flooding for the 1% annual probability flood event.

A small extent of grade 3 agricultural land lies within the 0.1% annual probability flood event outline.

Environmental designation: Who and what are currently There are no internationally or nationally designated sites, SSSIs or SNCIs at risk most vulnerable to flood of flooding for the 1% or the 0.1% annual probability flood events within this damage and losses? policy unit.

Landscape: A small extent of the Sussex Downs AONB and South Downs proposed National Park lies within the 0.1% annual probability flood event outline.

Natural and Historic Environment: There are no listed buildings, registered historic parks and gardens, SMs or wet woodlands at risk of flooding for the 1% or 0.1% annual probability flood events. Climate change, through more intense rainfall events. Land use changes What are the key factors that contributing to increase in soil erosion, such as changes in crop type and could drive future flood risk? increases in livestock stocking density.

Environment Agency River Adur CFMP - Appendix B (September 2008) 198 What are the possible future Flood risk is currently assessed as low, and it is not expected to increase under levels of flood risk under the future scenarios. main scenarios? What potential responses (or groups of responses) are Potential to work with professional partners to derive better land management being considered to manage options so that run-off can be reduced and soil erosion avoided. flood risk? There is uncertainty about how effective changes in land management and vegetation cover will alter run-off at the catchment scale. It is known to work What gaps and uncertainties locally, but we do not yet know its effect on the catchment as a whole. are there in knowledge, and

Environment Agency River Adur CFMP - Appendix B (September 2008) 199 Form B6 Appraisal of policy options against policy unit objectives Policy unit 9 – South Downs (East) KEY = Scale of policy impact on objective: Not appraised Baseline Meets objective No impact Doesn’t meet object Uncertain The preferred policy option is indicated below by the policy option highlighted in pink Baseline (current Policy 1 Policy 2 Policy 3 Policy 4 Policy 5 Policy 6 and future) No maintenance of watercourses. Channels become blocked with vegetation and Reduction in conveyance is maintenance of Improved land use reduced. watercourses. Improved level of management through Introduce Channels become channel maintenance agri-environment The height of raised of watercourses. management Current and future blocked with vegetation schemes would embankments would practices that allow baseline with current and conveyance is Maintenance of the reduce surface run-off reduce over time. greater water flood risk reduced. channels continues. by woodland creation Localised protection retention within the management. to increase Deterioration of the measures introduced. policy unit i.e. change Deterioration over time interception of run-off small flood detention in land use. of the small flood and increase bunds at Bevendean. detention bunds at infiltration.

Bevendean. A do nothing approach would increase the flooding Catchment Targets and Opportunities and in an unmanaged and objectives Indicators Constraints unpredictable way. Economic objectives The level of channel and flood defence maintenance expenditure is likely to The current annual The level of channel remain the same or be Targets channel and flood and flood defence slightly less than Maintain a suitable defence maintenance Channel and flood maintenance The level of channel £1,000 as agri- balance of annual river Opportunities expenditure is No channel and flood Channel and flood defence maintenance expenditure will and flood defence environment schemes channel and flood - Improvements in the approximately £1,000; defence maintenance defence maintenance expenditure remains increase over time to maintenance reduce the level of defence maintenance efficiency of flood defence the annual average expenditure is maintenance processes. expenditure reduces to at approximately mitigate the affects of expenditure will management required. expenditure (£) to damages from fluvial incurred as no - To work with Defra and be less than £1,000. £1,000. Annual climate change to increase to be more Annual average Ensure that river annual average farmers to produce soil flooding to agriculture maintenance is Annual average average damages slightly more than than £1,000. Annual damages from fluvial channel and flood damages from fluvial management plans which are currently less than undertaken. Annual have a benefit to flood risk damages from fluvial from fluvial flooding to £1,000. Annual average damages flooding to agriculture defence maintenance flooding to agriculture £100. Annual average average damages through reducing the run-off flooding to agriculture agriculture increase average damages from from fluvial flooding are likely to remain expenditure is (£). rate. damages from fluvial from fluvial flooding are likely to be around over time due to the fluvial flooding to to agriculture are less than £100. appropriate to the Constraints flooding to agriculture to agriculture £1,000. affects of climate agriculture will remain estimated to be £0. agricultural economic Indicators - Available funding for the are unlikely to increase to be more initial set up of new flood risk change to be less than less than £100. The balance of damage in rural areas Balance of annual river significantly increase, than £2,000. management schemes. The balance of £150. The balance of expenditure to from flooding. channel and flood - Older flood defence being less than £150 expenditure to With better expenditure to damages will remain defence maintenance structures are likely to be in the future. The balance of more costly to maintain. damages becomes The balance of maintenance efficiency damages will be acceptable. expenditure (£) to expenditure to - Limited available information unacceptable over expenditure to and effective use of unacceptable with annual average on surface water and The current balance of damages is time. damages will remain funding the balance of expenditure being These flood risk damages from fluvial groundwater flood damages. expenditure to unacceptable. acceptable. expenditure to unjustifiably high. management flooding to agriculture damages is damages will remain practices would have (£). considered acceptable. the potential benefit of acceptable. reducing the flood risk in policy 6 (Brighton and Hove) downstream. Social objectives

Environment Agency River Adur CFMP - Appendix B (September 2008) 200 Ensure the impact of Targets Opportunities - Reduce flood risk and flooding on people No significant increase improve water quality by in the number of people promoting and encouraging and property does not No maintenance of significantly increase or properties affected by the use of SuDS in the the 1% annual proposed urban channels and in the future (for developments in Brighton probability fluvial flood drainage networks example due to and Hove, Worthing, would result in an event or surface water Shoreham and Burgess Hill. Approximately 0 climate change). - Continue local authority and increase in the flooding in the future people and 0 The increased Environment Agency support frequency, extent and It is likely that the No people and properties are at risk No people and frequency of flooding of the Flood 1 project in depth of localised number of people and No people and properties are likely Indicators relation to groundwater of localised fluvial properties are likely to will be managed such fluvial flooding. properties at risk of properties are likely to to be at risk of Number of people and flooding. flooding by the current be at risk of localised that the number of - Develop a flood warning localise fluvial flooding be at risk of localised localised fluvial properties affected by 1% annual probability fluvial flooding by the properties at risk in system for groundwater The number of may increase to be fluvial flooding by the flooding by the 1% the 1% annual flooding. flood event. This is 1% annual probability this policy unit is not people and properties more than zero. 1% annual probability annual probability probability fluvial flood Constraints not anticipated to flood event increased from the at risk of localise flood event flood event event - Government and international increase the future. current baseline and legislation, environmental flooding will increase There is no flood There is no flood there remains no management policies, plans to be more than 23 warning service Flood Warning Service There is no flood Coverage of Flood and strategies for the There are currently no warning service requirement for a and 10 respectively. available, which may is introduced. warning service Warning Service catchment must be complied properties covered by available. Flood Warning with, such as accommodating result in increased risk available. a flood warning Service. new housing within the There will be no flood to human life. catchment as detailed by the service. South East Plan and warning system compliance with the Habitats which may result in Directive. increased risk to - Visual impact of flood risk human life. management activities within the proposed National Park or Areas of Outstanding Natural Beauty. Environmental objectives The area of the There is currently 2 Sussex Downs 0km of the Sussex AONB and South The area of the Sussex Downs AONB and Downs proposed Downs AONB and The landscape South Downs ESA Opportunities National Park located South Downs proposed character of the Targets - Help meet national and proposed National within the 1% annual National Park located Sussex Downs AONB Increase the landscape biodiversity action plan (BAP) Park located within the targets. probability flood within the 1% annual and South Downs character value of the 1% annual probability There is no extent of There is no extent of There is no extent of event outline probability flood event proposed National Sussex Downs AONB flood event outline. the Sussex Downs the Sussex Downs the Sussex Downs Increase the landscape Constraints increases to be outline increases to be Park can be enhanced and South Downs - Some environmentally This is not expected to 2 AONB and South AONB and South AONB and South character value of the designated habitats are slightly more than around 0.01km . with the proposed National Park. increase in the future 2 Downs proposed Downs proposed Downs proposed Sussex Downs AONB susceptible to changes in 0.01km . implementation of with current flood risk National Park located National Park located National Park located and South Downs flood frequency, floodwater The landscape considered flood risk Indicators chemistry, groundwater management. within the 1% annual within the 1% annual within the 1% annual proposed National Park. The landscape character of the management Landscape character levels and drainage system probability flood event probability flood event probability flood maintenance. character of the Sussex Downs AONB practices, such as assessment of the The landscape outline. outline. event outline. - Changes to flood risk Sussex Downs and South Downs increasing the flood AONB and proposed character of the management can affect the AONB and South proposed National Park storage areas, in a National Park. landscape, its character and Sussex Downs AONB Downs proposed is unlikely to notably managed and value as an amenity. and South Downs National Park is alter due to such a controlled way. proposed National unlikely to notably minimal increase. Park is unlikely to alter due to such a alter. minimal increase. Does this policy change flood risk locally or elsewhere: Unlikely to significantly affect Increased water Reduced Reduced Increased Unlikely to adjacent policy retention through conveyance may conveyance may conveyance may significantly affect units, although agri-environmental benefit benefit downstream increase flood risk adjacent policy units improved retention schemes will benefit downstream areas areas downstream may benefit downstream areas downstream areas

Environment Agency River Adur CFMP - Appendix B (September 2008) 201 Form B7 – Summary of losses and gains.

Policy unit Policy Unit 9 - South Downs (East) name/number:

Preferred policy Policy options Losses Gains option relative to current baseline Policy option P1 Environmental NO LOSSES MEDIUM+ Not preferred option – Although the benefits to The landscape value the environment are of the Sussex Downs potentially high, AONB and South alterations to the Downs ESA/proposed landscape will be NP are likely to be unmanaged and beneficially altered but uncontrolled and in an unmanaged and therefore unpredictable. uncontrolled way In addition to this, the

AAD to agricultural land

resulting from this policy Social MEDIUM- NO GAINS will be unacceptably high. The number of people and property at risk

significantly increases

Economic HIGH- NO GAINS

In addition to this, the Social LOW- NO GAINS AAD to agricultural land The number of people resulting from this policy and property at risk will be unacceptably

significantly increases high.

Economic HIGH- NO GAINS

The balance of FRM expenditure to AAD is unacceptable with AAD to agricultural land

Environment Agency River Adur CFMP - Appendix B (September 2008) 202 increasing by more than £900 Policy option P3 Environmental NO LOSSES LOW+ Not preferred option – The potential benefits in The areas of the terms of the Sussex Downs AONB environment are not and South Downs sufficiently optimised ESA/proposed NP that under this policy. In fall within the 1% AEP addition to this, the AAD will increase slightly to agricultural land will but with no notable increase significantly in increase in landscape the future. value

Social NO LOSSES NO GAINS

Economic NO LOSSES LOW+

Social NO LOSSES NO GAINS

Economic NO LOSSES MEDIUM+

The balance of FRM expenditure to AAD will remain acceptable with slight increases in FRM expenditure to maintain AAD to agricultural land at current levels in the future Policy option P5 Environmental MEDIUM- NO GAINS Not preferred option – There are no gains The areas of the Sussex under this policy option. Downs AONB and South FRM expenditure is Downs ESA/proposed unacceptably high and NP that fall within the there will be negative 1% AEP will be impacts on the decreased which will Environment Agency River Adur CFMP - Appendix B (September 2008) 203 impact negatively on the landscape value of the landscape value area.

Social NO LOSSES NO GAINS

Economic HIGH- NO GAINS

The balance of FRM expenditure to AAD is unacceptable in with significant increases in FRM expenditure to reduce AAD to agricultural land Policy option P6 Environmental NO LOSSES HIGH+ Preferred Policy Option – There are no losses The landscape value under this policy option. of the Sussex Downs The potential benefits to AONB and South landscape value are Downs ESA/proposed maximised and will be NP will be enhanced in carried out in a a managed and managed and controlled controlled way way. The balance

between FRM and AAD

Key HIGH: High negative A policy has a ‘high negative’ effect where it could contribute to a social, economic or environmental objective in a significantly negative way. A ‘high negative’ effect could be: (i) a very large increase in current flood risk; (ii) very large projected increases in flood risk under future conditions, and/or; (iii) significant additional social, economic and/or environmental losses. MEDIUM: Medium negative A policy has a ‘medium negative’ effect where it could contribute to a social, economic or environmental objective in a negative way. A ‘medium negative’ effect could be: (i) an increase in current flood risk; (ii) a projected increase in flood risk under future conditions, and/or; (iii) social, economic and/or environmental losses. LOW: Low negative A policy has a ‘low negative’ effect where it could make a limited contribution to Environment Agency River Adur CFMP - Appendix B (September 2008) 204 a social, economic or environment objective, but where the overall contribution would be negative. A ‘low negative’ effect could be: (i) an overall increase in current flood risk; (ii) an overall increase in flood risk under future conditions, and/or; (iii) overall social, economic and/or environmental losses. NEUTRAL: Neutral A policy has a ‘neutral’ effect where it makes neither a positive or negative contribution to a social, economic or environmental objective. A ‘neutral’ effect could be: (i) no change in current level of risk. In this instance the current level of risk would have to be low, so that the residual risk after a neutral policy was implemented remained acceptable; (ii) no change in flood risk under future conditions. In this instance projected future risk would need to be low so that the residual risk after a neutral policy was implemented remained acceptable, and/or; (iii) no additional social, economic and/or environmental gains or losses. Policy options may also be ‘neutral’ where they are not relevant in a particular policy unit, or where it is not feasible for a policy option to contribute to an objective. HIGH: High positive A policy has a ‘high positive’ effect where it could contribute to a social, economic or environmental objective in a significantly positive way. A ‘high positive’ effect could be: (i) a very large reduction in current flood risk; (ii) avoiding/reducing very large projected increases in flood risk under future conditions, and/or; (iii) significant additional social, economic and/or environmental gains. MEDIUM: Medium positive A policy has a ‘medium positive’ effect where it could contribute to a social, economic or environmental objective in a positive way. A ‘medium positive’ effect could be: (i) a reduction in current flood risk; (ii) avoiding/reducing projected increases in flood risk under future conditions, and/or; (iii) additional social, economic and/or environmental gains. LOW: Low positive A policy has a ‘low positive’ effect where it could make a limited contribution to a social, economic or environment objective, but where the overall contribution would be positive. A ‘low positive’ effect could be: (i) an overall reduction in current flood risk; (ii) an overall avoidance/reduction in flood risk under future conditions,

Environment Agency River Adur CFMP - Appendix B (September 2008) 205 Form B8 Summary of preferred policy Policy unit 9 – South Downs (East) Physical characteristics: - Steep scarp slopes of the chalk downland hills extend the entire width of the CFMP area. - Environmentally Sensitive Area and Area of Outstanding Natural Beauty. - Shallow silty soils are well drained and the chalk is an important local aquifer for water supply. - Proposed National Park with high amenity value and landscape character. - Contains a large proportion of Scheduled Monuments and a significant proportion of SSSIs in the CFMP area. Flood mechanism: - No fluvial flooding within the policy unit. - Land management affects runoff rates with certain types of management causing muddy floods in adjacent urban areas. Receptor: Problem/risk - None within the policy unit. - Adjacent urban areas (particularly in Policy Unit 6 - Brighton and Hove) are receptors of flooding generated due to land management in this unit. Current Flood Risk Summary Number of properties at risk of flooding (1% annual probability flood event) 0 Total damages (approx.) (1% annual probability flood event) £0 Annual averages damages (approx.) Negligable Future Flood risk: - Flood risk is currently assessed as low, and it is not expected to increase under future scenarios. Future Flood Risk Summary (in 100 years time) Number of properties at risk of flooding (1% annual probability flood event) 0 Total damages (approx.) (1% annual probability flood event) £0 Annual averages damages (approx.) Negligable Policy 6 - Take action to increase the frequency of flooding to deliver benefits locally or Policy selected elsewhere, which may constitute an overall flood risk reduction (for example for habitat inundation). This policy can deliver benefits for people and the environment locally or in other policy units. By increasing flooding and infiltration of rainwater locally in this unit, flooding downstream can be reduced. Current maintenance activities include grass and weed cutting. The changes in land management can also benefit biodiversity. Policy 6 sets a framework that actively supports increased flooding and infiltration of rainwater and is appropriate to this policy unit for the following reasons: - Although flood risk is assessed as low within the policy unit, there is the opportunity to reduce flood risk in adjoining units. - Large rural policy unit which presents opportunities for changing land use and developing possible flood storage mechanisms to reduce rapid run-off generated from Justification land use activities and the steep slopes. - Action in this unit will help reduce risk of muddy floods in the suburbs of Brighton. - There are some opportunities for reducing downstream flooding by improving or creating new habitats, which increase water retention. - Soil erosion problems can best be tackled through more sensitive land management, land use change, and changes in farming practices. - Increased storminess due to climate change may increase soil erosion and localised flash flooding in neighbouring catchments. - This policy would help meet the environmental and landscape objectives by working with landowners and the Government. - Ensure that flood defence maintenance expenditure is appropriate to the agricultural Catchment economic damage in rural areas from flooding. objectives - Increase the landscape character value of the Sussex Downs AONB and South Downs proposed National Park. Opportunities: - Improvements in the efficiency of flood defence maintenance processes. - To work with Defra and farmers to produce soil management plans which have a benefit Catchment-wide to flood risk through reducing the run-off rate. opportunities - Help meet national biodiversity action plan (BAP) targets. and constraints - Continue local authority and Environment Agency support of the Flood 1 project in relation to groundwater flooding. - Develop a flood warning system for groundwater flooding.

Environment Agency River Adur CFMP - Appendix B (September 2008) 206

Constraints: - Available funding for the initial set up of new flood risk management schemes. - Older flood defence structures are likely to be more costly to maintain. - Limited available information on surface water and groundwater flood damages. - Some environmentally designated habitats are susceptible to changes in flood frequency, floodwater chemistry, groundwater levels and drainage system maintenance. - Changes to flood risk management can affect the landscape, its character and value as an amenity. - Visual impact of flood risk management activities within the proposed National Park or Areas of Outstanding Natural Beauty. - Government and international legislation, environmental management policies, plans and strategies for the catchment must be complied with, such as accommodating new housing within the catchment as detailed by the South East Plan and compliance with the Habitats Directive. Policy 1 - do nothing. Although this could be considered as a possible policy option, and would have a similar long-term result as policy 6, it would limit the opportunities to reduce soil erosion and surface water run-off that affect neighbouring policy units.

Policy 2 - reduce current level of flood risk management. There is already minimal flood risk management within this policy unit. It is not possible to reduce it further.

Policy 4 - maintain the current level of flood risk into the future. As with policy 3, this policy could apply, but it implies a level of activity that is not happening.

Policy 5 - reduce the level of flood risk, both now and in the future. This policy is not justified by the level of flood risk within the policy unit. There is uncertainty about how effective changes in land management and vegetation cover will alter run-off at the catchment scale. It is known to work locally, but we do not yet know its effect on the catchment as a whole. Uncertainties

and Changes in land management will depend on the agreement of landowners. dependencies

The understanding of the impact of climate change on groundwater is still in its infancy, and there is still a lot of uncertainly surrounding the impact on groundwater flooding events.

Environment Agency River Adur CFMP - Appendix B (September 2008) 207

Form B9 Requirements for further policy development and appraisal Policy unit 9 – South Downs (East) Is there a need for further policy development? No If yes, then mark policy options for more detailed development. Some complex policies may require more detailed development, probably at Strategy Plan level. Is there a need for further more detailed appraisal? No If yes, take forward to strategy study.

Environment Agency River Adur CFMP - Appendix B (September 2008) 208

Form B10 Indicators for monitoring, review and evaluation This form sets out the indicators that need to be included in the policy implementation plan, for policy monitoring, drawing on the residual risks and likely impacts identified above. This will allow better review and evaluation of the policy when implemented. Policy unit 9 – South Downs (East) Indicators to be included in policy unit 9 implementation plan are:

Economic - Balance of annual flood risk maintenance expenditure (£) to annual average damages from fluvial flooding to agriculture (£). - Flood damages downstream in policy unit 6 (Brighton and Hove) (£).

Social - The estimated number of properties affected by Downland ‘muddy’ surface water flooding downstream in policy unit 6 (Brighton and Hove).

Environmental - Landscape character assessment of the AONB and proposed National Park.

Environment Agency River Adur CFMP - Appendix B (September 2008) 209

Signature of Form B11 CFMP Project Gary Lane Manager:

Date (of completion): September 2008

Environment Agency River Adur CFMP - Appendix B (September 2008) 210 B4.2 Assessment and evaluation of impacts

The alternative options have been assessed against objectives that are specific for each policy unit. The tables set out below detail this appraisal. These tables identify the losses and gains under each of the six generic policy options and identify the preferred option for each policy unit along with monitoring requirements. As such they set out the findings of the SEA in relation to the assessment of options.

In consultation with Natural England we have demonstrated that as a result of this CFMP there will be no significant impacts on Natura 2000 sites as there are no designated sites within the CFMP area.

Information on mitigation and enhancement measures related to the preferred policy option identified for each policy unit is set out in section B4.4.

At this level of plan, the mitigation and enhancement measures are integral to the policy appraisal. Where we have the potential to enhance the environment we have included this potential within the appraisal objectives. Mitigation measures at this level are generally included as part of the policy options, so that a less detrimental impact will tend to be an alternative policy option. We therefore can not identify any further specific mitigation measures at the policy level. At a lower level in our planning hierarchy, when we are investigating the details of how we will implement flood risk management measures, we will be undertaking an appropriate level of environmental assessment which will, in turn, identify more relevant mitigation measures to the impacts arising.

4.3 Cumulative environmental effects

SEA requires assessment of cumulative and synergistic effects. This section sets out the significant environmental effects of the plan as a whole, which have been considered in relation to each of the environmental objectives. It goes on to consider the environmental effects of potential interactions between the CFMP and relevant plans and programmes within the catchment. These findings are summarised in Table B5 below.

Environment Agency River Adur CFMP - Appendix B (September 2008) 211 Table B5 Summary of cumulative issues Catchment objective Cumulative effects across the whole plan area Interaction of CFMP with relevant Plans and Programmes PU1 PU2 PU3 PU4 PU5 PU6 PU7 PU8 PU9 Sum of policy unit P6 P4 P3 P6 P3 P3 P4 P6 P6 impacts

HIGH LOW HIGH LOW HIGH HIGH N/A N/A N/A HIGH + + + + + + +

Restore rivers and Flood water storage can be effectively increased through strategic restoration of Adur and Ouse Catchment Abstraction floodplains to a naturally river and floodplain function. This will reduce flood risk to people, properties, Management Scheme functioning state where critical infrastructure and other valuable environmental and historic assets The CFMP will have the opportunity to feasible. downstream. The strategy of this CFMP is to restore the rivers and floodplains of influence the water quality concerns the River Adur and its east and west tributaries in the upper catchment as well as associated with the large Goddards Green introducing managed floodwater storage in these areas. By relaxing flood waste water treatment works discharges to defences and allowing natural processes to be restored in a managed and the east branch of the River Adur. The CFMP predictable way, the frequency of flooding will increase as will water retention. has the opportunity to improve water resource This will have the benefit of reducing flood risk in the high-risk downstream areas efficiency and abstraction issues. of Worthing, Brighton, Hove, Shoreham, Steyning and Upper Beeding without the need for extensive FRM improvements. Increased FRM in Burgess Hill and Regional Forestry and Woodlands Hassocks under a policy option 4 could potentially increase flows into the Upper Framework for the South East Adur as they bypass the urban areas. By increasing storage in the Upper Adur, There is potential for positive interaction with this potential impact will not be passed on to urban areas downstream and will the CFMP to encourage more environmentally instead be retained in rural areas where wetland habitats can be created. sensitive land management practices. This framework includes provisions for riverbank Managing this potential carefully will also ensure risks in the policy units in which stabilisation and tree planting targets. flooding frequency is increased can be minimised where it has the potential to cause harm to isolated settlements or environmental receptors. There is also The High Weald AONB Management Plan potential to restore river channels in some of the urban areas of the catchment, There are objectives within the AONB namely Steyning, Upper Beeding and Worthing, with the aim to reduce flows by Management Plan to reduce flood risk through increasing capacity and river bank naturalisaton. This will bring additional local restoration and protection of functional improvements to the environmental and amenity value of these urban corridors. floodplains which is a direct opportunity for positive interactions with the CFMP. Restoring river channels and floodplains to their natural state will also bring significant environmental benefits in terms of creating valuable wetland habitats or South Downs Management Plan important species. There will be great potential to contribute to UK and local BAP This plan contains policies to alleviate

Environment Agency River Adur CFMP - Appendix B (September 2008) 212 Catchment objective Cumulative effects across the whole plan area Interaction of CFMP with relevant Plans and Programmes PU1 PU2 PU3 PU4 PU5 PU6 PU7 PU8 PU9 Sum of policy unit P6 P4 P3 P6 P3 P3 P4 P6 P6 impacts targets as well as enhancing existing designated sites such as the Adur Estuary abstraction pressure through increased SSSI and several SNCIs. Managing this potential carefully under policy option 6 storage within the catchment, to improve river will ensure any potentially negative impacts can be avoided. flow and reduce flood risk in vulnerable areas through floodplain and wetland restoration and Increasing water retention in the upper catchment, Adur Valley and South Downs maintenance of water flow to ditches. These may have an impact on the landscape character of the High Weald and Sussex aims are complemented very well by the Downs AONBs, proposed South Downs National Park and South Downs ESA, as policies of this CFMP although the future well as the general landscape character area. The areas of these designated National Park status may bring other landscapes that are affected by flooding are minimal and if water retention is constraints. managed in a careful and predictable manner, negative impacts will be highly unlikely. In fact, this is more likely to enhance the character and value of these Destination South East Proposed landscapes. However, it is unlikely that such enhancements will have a significant Alterations to Regional Planning Guidance, impact on the tourism and amenity value of the designated areas, however, the Tourism and Related Sport and Recreation general landscape character areas may be enhanced bringing potential for a There is potential for positive interactions as wider range of recreation activities associated with water bodies and wetland the CFMP will seek to support the long term habitats. aims of conserving and enhancing the environment, avoiding damaging activities and promoting appropriate activities such as water sports, angling, ecology/nature and walking which can be associated with natural riverine habitats.

HIGH MED MED MED LOW MED MED N/A N/A HIGH + + + + + + + +

Environment Agency River Adur CFMP - Appendix B (September 2008) 213 Catchment objective Cumulative effects across the whole plan area Interaction of CFMP with relevant Plans and Programmes PU1 PU2 PU3 PU4 PU5 PU6 PU7 PU8 PU9 Sum of policy unit P6 P4 P3 P6 P3 P3 P4 P6 P6 impacts Protect and enhance There are numerous SSSIs within the CFMP area, of which only the Adur Estuary Land Use Management Plans (various) nationally and SSSI is at relative risk from a 1% annual probability flood event. There are also There is potential for positive interaction as internationally important several SNCIs at risk from flooding, with a total area of 3.3km2 falling within the the plans will seek to implement more species and habitats. 1% annual probability outline. Increasing water retention in the upper catchment sensitive land management practices. This will and river channels will have a positive impact on the water-dependent Adur support and encourage the protection and Estuary SSSI and the River Adur Water Meadows, Wyckham Wood and the enhancement of biodiversity and there may be Ferring Rife and Meadows SNCIs. However, retention of water will have to be assistance for investment in resources related carefully planned and managed to protect any sensitive designated sites or to soil and water management and habitats from flood damage. There is an expected net benefit to BAP priority conservation, particularly in policy units 1, 4, 8 habitats such as wet woodland and coastal and floodplain grazing marsh and and 9. associated species such as the brown/sea trout, otter and great crested newt. UK BAP and Local BAP for Sussex Changes in rural land management will have a positive impact on the biodiversity Positive interactions are likely to arise and of habitats and species. By strategically implementing policy option 6, it is more there may be opportunities for habitat creation likely that these aims can be achieved in a predictable and manageable way. This and protection and expansion of designated policy will encourage the uptake of agri-environment schemes with the aim of sites. The BAP habitats and species reducing run-off and flood risk. However, these schemes will also lead to associated with these sites will also benefit significant environmental improvements in terms of water quality, soil from the policies of the CMFP. There is also management and habitat protection and enhancement. potential for outcomes of the CFMP to be incorporated into future revision of BAP Habitat and Species Action Plans.

Local Development Frameworks (various) There is potential for positive interactions as polices contained within the Local Plans aim to sustain and improve biodiversity and the natural environment, and help ensure their protection beyond the duration of the CFMP. As many of these planning frameworks are in the development stages, there will be opportunities for the CFMP to inform this

Environment Agency River Adur CFMP - Appendix B (September 2008) 214 Catchment objective Cumulative effects across the whole plan area Interaction of CFMP with relevant Plans and Programmes PU1 PU2 PU3 PU4 PU5 PU6 PU7 PU8 PU9 Sum of policy unit P6 P4 P3 P6 P3 P3 P4 P6 P6 impacts process.

The High Weald AONB Management Plan There are objectives within the AONB Management Plan to protect and enhance UK and local BAP priority species and habitats, particularly wetlands, wet woodlands and riverine habitats, which is a direct opportunity for positive interactions with the CFMP.

River Basin Management Plan There are opportunities for this to interact positively with the CFMP to achieve common aims to protect and enhance biodiversity, BAP priority species and habitats and designated fisheries through improvements in water quality. Improvements in water quality will bring added benefits in terms of FRM. There is significant opportunity for these plans to coordinate approaches in the early stages of their development.

Regional Forestry and Woodlands Framework for the South East There is potential for positive interaction with the CFMP to encourage more environmentally sensitive land management practices, and opportunities to increase tree planting may help to alleviate damaging flows, particularly in policy units 1, 4, 8 and 9.

Environment Agency River Adur CFMP - Appendix B (September 2008) 215 Catchment objective Cumulative effects across the whole plan area Interaction of CFMP with relevant Plans and Programmes PU1 PU2 PU3 PU4 PU5 PU6 PU7 PU8 PU9 Sum of policy unit P6 P4 P3 P6 P3 P3 P4 P6 P6 impacts

MED HIGH MED MED HIGH MED MED LOW - LOW - + + + - + + + MEDIUM +

Ensure the impact of There are approximately 400 people at risk of flooding (1% annual probability Regional Spatial Strategy for the South flooding on people and flood event) across the CFMP area with this number set to increase significantly to East properties does not nearly 6,000 in the next 50-100 years. The majority of this increase is predicted in There is potential for negative interaction if significantly increase in Shoreham where climate change and sea level rise are likely to cause very strategic development is located in areas at the future (for example significant increases in flood risk. The overall combination of policies for this severe risk of flooding, such as Shoreham, due to climate change). CFMP will ensure the number of people and properties at risk from flooding does Brighton and Hove and Worthing, particularly not increase significantly in the future. as the RSS will extend beyond the duration of this CFMP. However, given that development The risk of flooding in the Lower Adur catchment will not increase significantly in should only be permitted in line with PPS 25, the future due to strategic water storage in the upper catchment coupled with this is unlikely to be significant. increased defences around Shoreham. The current levels of FRM in Worthing, Brighton, Hove, Steyning and Upper Beeding, in combination with strategic flood Local Development Frameworks (various) water attenuation, will ensure there are no significant increases in flood risk in the There is potential for negative interactions if future. Although flood risk to individual properties could potentially increase in the the Local Plans allow significant development rural areas of the catchment Upper Adur and South Downs, these should be to occur in areas at risk of flooding, due to protected through carefully managed water storage under policy option 6. The flood risk management activities throughout flood risk to people and properties in Burgess Hill will not increase in the future the catchment, particularly as Local Plans will due to increased FRM to maintain current levels. Implementing policy option 4 in extend beyond the duration of the CFMP. the high flood risk area of Shoreham will also mitigate the potentially severe However, given that development should only impacts of climate change and sea level rise. be permitted in line with PPS 25, this is unlikely to be significant. As many of these planning frameworks are in the development stages, there may be opportunities for the CFMP to inform the process and avoid future increases in flood risk. There is also potential to minimise the extents, frequency and duration of flooding through implementation of SuDS in the new emerging LDFs which will in

Environment Agency River Adur CFMP - Appendix B (September 2008) 216 Catchment objective Cumulative effects across the whole plan area Interaction of CFMP with relevant Plans and Programmes PU1 PU2 PU3 PU4 PU5 PU6 PU7 PU8 PU9 Sum of policy unit P6 P4 P3 P6 P3 P3 P4 P6 P6 impacts turn reduce risk to life.

Beachy Head to Selsey Bill Shoreline Management Plan There is potential for positive interactions between the SMP and CFMP to reduce flood risk to Shoreham Harbour and the River Adur in the future, where the policy is to hold the line.

South Downs Management Plan This plan contains policies to alleviate abstraction pressure through increased storage within the catchment, to improve river flow and reduce flood risk in vulnerable areas through floodplain and wetland restoration and maintenance of water flow to ditches. These aims are complemented very well by the policies of this CFMP although the future National Park status may bring other constraints.

Land Use Management Plans (various) There is potential that positive interaction between the plans as policies may result in reduced run-off and mitigation against climate change, particularly in policy units 1, 4, 8 and 9.

Regional Forestry and Woodlands Framework for the South East

Environment Agency River Adur CFMP - Appendix B (September 2008) 217 Catchment objective Cumulative effects across the whole plan area Interaction of CFMP with relevant Plans and Programmes PU1 PU2 PU3 PU4 PU5 PU6 PU7 PU8 PU9 Sum of policy unit P6 P4 P3 P6 P3 P3 P4 P6 P6 impacts Positive interactions may potentially arise in those parts of the catchment where CFMP policies support sustainable land management, including tree planting schemes which will help to alleviate flood flows, particularly in policy units 1, 4, 8 and 9.

MED HIGH MED MED HIGH MED MED LOW - LOW - + + + - + + + MEDIUM +

Ensure the disruption It is expected that this combination of policies will ensure that flood risk to critical Regional Spatial Strategy for the South caused by flooding to infrastructure and transport routes does not increase significantly in the future. East transport and critical The urban areas of Burgess Hill, Hassocks and Shoreham will be well protected There is potential for negative interaction if infrastructure does not against increased flood risk through the implementation of policy option 4 which strategic development is located in areas at significantly increase in will increase FRM to maintain current levels of risk into the future. The risk of flooding, such as Shoreham, Brighton the future (for example combination of water retention upstream and maintained defences in Brighton, and Hove and Worthing, particularly as the due to climate change). Hove, Steyning, Upper Beeding and Worthing will also ensure no significant RSS will extend beyond the duration of this increases in flood risk to these urban areas. The careful management of CFMP. However, given that development floodwater attenuation in the Upper Adur and Adur Valley will also mitigate against should only be permitted in line with PPS 25, disruption to the A roads and railways within these policy units. this is unlikely to be significant.

Local Development Frameworks (various) There is potential for negative interactions if the Local Plans allow significant development to occur in areas at risk of flooding, due to flood risk management activities throughout the catchment, particularly as Local Plans will extend beyond the duration of the CFMP. However, given that development should only be permitted in line with PPS 25, this is unlikely to be significant. As many of these

Environment Agency River Adur CFMP - Appendix B (September 2008) 218 Catchment objective Cumulative effects across the whole plan area Interaction of CFMP with relevant Plans and Programmes PU1 PU2 PU3 PU4 PU5 PU6 PU7 PU8 PU9 Sum of policy unit P6 P4 P3 P6 P3 P3 P4 P6 P6 impacts planning frameworks are in the development stages, there may be opportunities for the CFMP to inform the process and strategically reduce disruption and damage during severe flood events.

Environment Agency River Adur CFMP - Appendix B (September 2008) 219 Catchment objective Cumulative effects across the whole plan area Interaction of CFMP with relevant Plans and Programmes PU1 PU2 PU3 PU4 PU5 PU6 PU7 PU8 PU9 Sum of policy unit P6 P4 P3 P6 P3 P3 P4 P6 P6 impacts and 9.

Regional Forestry and Woodlands Framework for the South East Positive interactions may potentially arise in those parts of the catchment where CFMP policies support sustainable land management, including tree planting schemes which may help to alleviate flood flows, particularly in policy options 1, 4, 8 and 9.

MED HIGH MED HIGH HIGH N/A N/A LOW - N/A + + - + + MEDIUM +

Reduce the impact of Muddy flooding is a problem in parts of northern Brighton and Hove, Rottingdean, Land Use Management Plans (various) muddy flooding. Woodingdean, Ovingdean, Bevendean, Worthing and Findon with a significant There is potential that positive interaction number of properties affected. This nuisance flooding is caused by surface water between the plans as policies may result in run-off and associated soil erosion from the South Downs. Changes in farming reduced run-off and improved soil practices from pasture to arable have resulted in an associated increase in management, particularly in policy options 1, flooding and erosion. By implementing policy option 6 in the South Downs and 4, 8 and 9. These schemes may also Adur Valley, sustainable land management and agri-environment schemes will be contribute towards restoration of natural encouraged and the natural function of the River Adur channel and floodplain will processes which will reduce soil erosion. be restored where possible. This will lead to a reduction in muddy flooding through a combination of soil management, reduced surface water run-off and Regional Forestry and Woodlands transportation and sedimentation processes. Framework for the South East Positive interactions may potentially arise in those parts of the catchment where CFMP policies support sustainable land management, including tree planting schemes which may help to alleviate run-off and soil erosion, particularly in policy options 1, 4, 8

Environment Agency River Adur CFMP - Appendix B (September 2008) 220 Catchment objective Cumulative effects across the whole plan area Interaction of CFMP with relevant Plans and Programmes PU1 PU2 PU3 PU4 PU5 PU6 PU7 PU8 PU9 Sum of policy unit P6 P4 P3 P6 P3 P3 P4 P6 P6 impacts and 9.

The High Weald AONB Management Plan There are objectives within the AONB Management Plan to reduce flood risk through restoration and protection of functional floodplains which is a direct opportunity for positive interactions with the CFMP.

South Downs Management Plan This plan contains policies to improve river flow through floodplain and wetland restoration and maintenance of water flow to ditches. This will interact positively with objectives to reduce surface water run-off and soil erosion in the South Downs.

MED HIGH MED MED MED MED HIGH MED MED + + - + - - + + + LOW +

Ensure flood damages do Across the CFMP area, AAD due to the flooding of properties and agricultural land Regional Spatial Strategy for the South not significantly increase currently stands at approximately £5 million, the majority of which occurs in the East in the future (for example densely populated Lower Adur and Ferring Rife catchments. This is expected to There is potential for negative interaction if due to climate change). rise by a further £10 million in the future. The strategy of increasing water storage strategic development and infrastructure is capacity in the upper catchment and increasing flood defences around high-risk located in areas at risk of flooding, such as urban areas such as Steyning, Upper Beeding and Shoreham will ensure that Shoreham, Brighton and Hove and Worthing, AAD to both properties and agricultural land will not increase significantly in the particularly as the RSS will extend beyond the future. It is also expected that carefully managed floodwater attenuation in the duration of this CFMP. However, given that upper catchment will be sufficient to ensure flood risk does not increase in the development should only be permitted in line future in downstream Worthing, Brighton, Hove, Steyning and Upper Beeding with PPS 25 this is unlikely to be significant.

Environment Agency River Adur CFMP - Appendix B (September 2008) 221 Catchment objective Cumulative effects across the whole plan area Interaction of CFMP with relevant Plans and Programmes PU1 PU2 PU3 PU4 PU5 PU6 PU7 PU8 PU9 Sum of policy unit P6 P4 P3 P6 P3 P3 P4 P6 P6 impacts without the need to increase FRM in these urban areas. Local Development Frameworks (various) The AAD to agricultural land can be managed through carefully controlled flood There is potential for negative interactions if attenuation in the upper catchment which will reduce risk within these policy units the Local Plans allow significant development and should be located in areas where additional damages will not be sustained. to occur in areas at risk of flooding, due to By encouraging the uptake of agri-environment schemes in these parts of the flood risk management activities throughout catchment, further reductions in AAD may be achieved, as well as other the catchment, particularly as Local Plans will environmental benefits. extend beyond the duration of the CFMP. However, given that development should only be permitted in line with PPS 25, this is unlikely to be significant. Plans for growth in areas of Worthing, Brighton and Hove and Shoreham are likely to lead to increased damages in the future, however, the CFMP has taken these increased risks into consideration during policy appraisal and will interact to reduce or prevent an increase in these effects where possible.

South Downs Management Plan This plan contains policies to alleviate abstraction pressure through increased storage within the catchment, to improve river

Environment Agency River Adur CFMP - Appendix B (September 2008) 222 Catchment objective Cumulative effects across the whole plan area Interaction of CFMP with relevant Plans and Programmes PU1 PU2 PU3 PU4 PU5 PU6 PU7 PU8 PU9 Sum of policy unit P6 P4 P3 P6 P3 P3 P4 P6 P6 impacts flow and reduce flood risk in vulnerable areas through floodplain and wetland restoration and maintenance of water flow to ditches. These aims are complemented very well by the policies of this CFMP although the future National Park status may bring other constraints.

Land Use Management Plans (various) There is potential for positive interactions where the CFMP implements policies that support and encourage sustainable land management practices, which may reduce the velocity and volume of run off, particularly in policy units 1, 4, 8 and 9.

Regional Forestry and Woodlands Framework for the South East Potentially positive interactions where the CFMP encourages more sustainable land management practices and opportunities to increase tree planting may help to alleviate flood flows, particularly in policy option 1, 4 8 and 9.

HIGH HIGH LOW HIGH LOW MED HIGH HIGH HIGH + + + + + - + + + HIGH +

Environment Agency River Adur CFMP - Appendix B (September 2008) 223 Catchment objective Cumulative effects across the whole plan area Interaction of CFMP with relevant Plans and Programmes PU1 PU2 PU3 PU4 PU5 PU6 PU7 PU8 PU9 Sum of policy unit P6 P4 P3 P6 P3 P3 P4 P6 P6 impacts Ensure that river channel Whether the cost of FRM expenditure is justifiable and appropriate has been See above and flood defence assessed by comparing the ratios of AAD prevented (the difference between maintenance expenditure policy option 1 and the policy option chosen) and the annual cost of FRM within a is appropriate to the policy unit, for each policy option. This tests whether the annual costs of FRM do economic damage of not exceed the AAD prevented, in which case it is considered appropriate and flooding. justifiable.

The cumulative effects of the policies chosen in this CFMP are highly positive in terms of this measure. Nearly every policy chosen for every policy unit is shown to have positive effects, which demonstrates that there are few losses sustained under this CFMP and that nearly every unit of FRM expenditure brings returns greater than one equivalent unit of AAD prevented. The highest returns are made under policy options 1, 2, 4, 7, 8 and 9 which cover the large rural areas of the Adur catchment, the South Downs, Shoreham and Burgess Hill. The only policy unit in which the ratio is unacceptable is Brighton and Hove, where policy option 3 limits the gains in terms of AAD prevented. However, it is the aim of this CFMP to further reduce AAD through strategic attenuation of flood water upstream.

Environment Agency River Adur CFMP - Appendix B (September 2008) 224 B4.4 Mitigation and Enhancement

At this level of policy making, where we are setting the direction for future actions, the mitigation and enhancement measures are integral to the policy appraisal. Where we have the potential to enhance the environment we have included this potential within the appraisal as opportunities. Mitigation measures at this level are generally included as part of the policy options, so that a less detrimental impact will tend to be implicit within an alternative policy option. At a lower level in our planning hierarchy, when we are investigating the details of how we will implement flood risk management measures, we will be undertaking an appropriate level of environmental assessment and consultation which will, in turn, identify more relevant mitigation measures to the impacts arising. We will use the assessment of impacts undertaken at this level to help focus our lower levels of decision making, ensuring that relevant mitigation and enhancement measures are explored fully.

Where Table B5 identifies potential benefits / impacts between the CFMP and other plans / programmes operating within the catchment we will take this into account when developing further proposals, as set out above.

B4.5 Monitoring

SEA requires significant environmental effects related to the implementation of the plan to be monitored. Information on the monitoring requirements related to the implementation of the CFMP is included in the appraisal tables presented in Section B4.2.

The monitoring of the significant effects of the plan will be based on the following indicators (in no particular order):

a) Change in AAD to properties (£); b) Change in AAD to agricultural land (£); c) Change in estimated damages resulting from surface water flooding (£) d) Change in number of people affected by 1% annual probability flood outline; e) Change in estimated number of properties affected by surface water and/or groundwater flooding; f) Change in the estimated number of properties affected by downland ‘muddy’ surface water flooding; g) Change in length of main roads affected by 1% annual probability flood outline (km); h) Change in number of critical infrastructure sites affected by the 1% annual probability fluvial flood event; i) Change in the number and period of recorded A road and railway closures due to surface water flooding; j) Change in the number if critical infrastructure sites recorded as being affected by surface water flooding; k) Change in balance of annual river channel and flood defence maintenance (£) to annual average damages from fluvial flooding to agriculture (£); l) Change in area of naturally active floodplain restored (km2); m) Change in length of naturally functioning river (km); n) Achievement of BAP targets and improved habitat quality and species diversity; and o) Change in landscape character assessment of the AONB, ESA and/or proposed National Park.

References Project Appraisal Guidance – Supplementary Guidance: Treatment of climate change impacts. Defra October 2006. (http://www.defra.gov.uk/environ/fcd/pubs/pagn/climatechangeupdate.pdf)

Environment Agency River Adur CFMP - Appendix B (September 2008) 225