River Adur Catchment Flood Management Plan Summary Report December 2009 managing flood risk We are the Environment Agency. It’s our job to look after your environment and make it a better place – for you, and for future generations. Your environment is the air you breathe, the water you drink and the ground you walk on. Working with business, Government and society as a whole, we are making your environment cleaner and healthier. The Environment Agency. Out there, making your environment a better place. Published by: Environment Agency Guildbourne House Chatsworth Road Worthing, West Sussex BN11 1LD Tel: 08708 506 506 Email: [email protected] www.environment-agency.gov.uk © Environment Agency All rights reserved. This document may be reproduced with prior permission of the Environment Agency. Introduction I am pleased to introduce our summary of the River Adur Catchment Flood Management Plan (CFMP). This CFMP gives an overview of the flood risk in the River Adur catchment and sets out our preferred plan for sustainable flood risk management over the next 50 to 100 years. The River Adur CFMP is one of 77 CFMPs for England The main source of flood risk in the Adur CFMP area is and Wales. Through the CFMPs, we have assessed from both localised river flooding, which is made worse inland flood risk across all of England and Wales for by the influence of the tide, and surface water flooding, the first time. The CFMP considers all types of inland which is also a problem in some urban areas caused by flooding, from rivers, groundwater, surface water and under capacity or blockages in the drainage network. tidal flooding, but not flooding directly from the sea The risk is mainly located in Steyning and Upper (coastal flooding), which is covered by Shoreline Beeding, Brighton and Hove and Worthing. Management Plans (SMPs). Our coverage of surface We cannot reduce flood risk on our own, we will and groundwater is however limited due to a lack of therefore work closely with all our partners to improve available information. the co-ordination of flood risk activities and agree the The role of CFMPs is to establish flood risk most effective way to management flood risk in the management policies which will deliver sustainable future. The key partners we have worked with are Adur flood risk management for the long term. This is District Council, Arun District Council, Brighton and Hove essential if we are to make the right investment City Council, Defra, Horsham District Council, Mid Sussex decisions for the future and to help prepare ourselves District Council, Natural England, Southern Water, West effectively for the impact of climate change. We will Sussex County Council, Worthing Borough Council. use CFMPs to help us target our limited resources This is a summary of the main CFMP document, if you where the risks are greatest. need to see the full document an electronic version This CFMP identifies flood risk management policies to can be obtained by emailing assist all key decision makers in the catchment. It was [email protected] or alternatively produced through a wide consultation and appraisal paper copies can be viewed at any of our offices in process, however it is only the first step towards an Southern Region. integrated approach to flood risk management. As we all work together to achieve our objectives, we must monitor and listen to each others progress, discuss what has been achieved and consider where we may Toby Willison need to review parts of the CFMP. Regional Director, Southern Region Environment Agency River Adur Catchment Flood Management Plan 3 Contents The purpose of a CFMP in managing flood risk 5 Catchment overview 6 Current and future flood risk 8 Future direction for flood risk management 10 Sub-areas 1 Upper Adur 13 2 Burgess Hill and Hassocks 14 3 Steyning and Upper Beeding 16 4 Adur South Downs (West) 17 5 Worthing 18 6 Brighton and Hove 19 7 Shoreham and Adur Estuary 20 8 Adur Valley (north of A27 to south Steyning) 22 9 Adur South Downs (East) 24 Map of CFMP policies 25 4 Environment Agency River Adur Catchment Flood Management Plan The purpose of a CFMP in managing flood risk CFMPs help us to understand the • IDBs, water companies and CFMPs aim to promote more scale and extent of flooding now other utilities to help plan their sustainable approaches to managing and in the future, and set policies activities in the wider context flood risk. The policies identified in for managing flood risk within the of the catchment; the CFMP will be delivered through a catchment. CFMPs should be used combination of different approaches. • Transportation planners; to inform planning and decision Together with our partners, we making by key stakeholders such as: • Land owners, farmers and will implement these approaches land managers that manage through a range of delivery plans, • The Environment Agency, who will and operate land for projects and actions. use the plan to guide decisions agriculture, conservation on investment in further plans, The relationship between the CFMP, and amenity purposes; projects or actions; delivery plans, strategies, projects • The public and businesses to and actions is shown in figure 1. • Regional planning bodies and enhance their understanding local authorities who can use the of flood risk and how it will plan to inform spatial planning be managed. activities and emergency planning; Figure 1. The relationship between CFMPs, delivery plans, projects and actions. Policy planning • CFMPs and Shoreline Management Plans. • Action plans define requirement for delivery plans, projects and actions. Policy delivery plans (see note) Projects and actions • Influence spatial planning to reduce risk • Make sure our spending delivers the best and restore floodplains. possible outcomes. • Prepare for and manage floods • Focus on risk based targets, for example (including local flood warning plans). numbers of households at risk. • Managing assets. • Water level management plans. • Land management and habitat creation. Note: Some plans may not be led by us – we may • Surface water management plans. identify the need and encourage their development. Environment Agency River Adur Catchment Flood Management Plan 5 Catchment overview The River Adur CFMP covers an area parks and gardens within the plain. The Low Weald north of the of 600 square kilometres and is catchment. It also includes the High South Downs is characterised by home to around 550,000 people. Weald and South Downs, both low-lying and gently undulating clay The main urban centres are located designated as Areas of Outstanding vales. The landscape is a mixture of along the coast, including Worthing, Natural Beauty (AONBs). Much of fields, hedgerows and woodland. Shoreham, and the city of Brighton the South Downs is also classified The watercourses within the CFMP and Hove. Inland towns include as an Environmentally Sensitive include the main River Adur and its Burgess Hill, Steyning and Upper Area (ESA). The catchment tributaries which drain the Low Weald Beeding, as well as smaller encompasses eight Sites of Special area through the South Downs, settlements, such as Hassocks, Scientific Interest (SSSIs), flowing out to sea at Shoreham. The Henfield, and Partridge Green. designated because of their physical characteristics of the River ecological or geological importance. The history, landscape and natural Adur play an important role in the The Adur Estuary SSSI is of beauty of the area make it an highly valued landscape character particular significance due to its important recreational and tourist of the area. Other watercourses of saltmarsh habitat. destination. There are numerous note are the Ferring Rife and Teville scheduled monuments, listed The chalk outcrop of the South Stream which drain the coastal area buildings and registered historic Downs rises gently from the coastal to the west of the River Adur. ‘The physical characteristics of the River Adur play an important role in the highly valued landscape character of the area.’ ➜ Shoreham Harbour. Shoreham is a key coastal urban area, typical of where flood risk and development pressures need to be managed. 6 Environment Agency River Adur Catchment Flood Management Plan Map 1. Overview map of The Adur CFMP. ‘The catchment topography and geology both have a significant influence on the flooding characteristics of the catchment.’ Environment Agency River Adur Catchment Flood Management Plan 7 Current and future flood risk Overview of the current flood risk Where is the risk? Flood risk is the combination of the on the lower reaches of the Adur, on The map on page 10 illustrates the likelihood of a flood occurring and the Ferring Rife and on Teville consequences of a 1% annual the consequences when it does. We Stream. There is also a risk of probability event (1 in 100 year) have assessed flood risk across the flooding from groundwater, surface occurring in the CFMP area. CFMP area using broad-scale water run-off from the land, and The areas with the highest computer modelling, though overloaded drainage networks. concentration of properties making best use of existing There have been several river currently at risk from river flooding knowledge and models where flooding events over the last century are tabulated opposite: appropriate. Flood risk figures take and a number of groundwater into account current flood defences. flooding incidents. Groundwater Serious flooding does not occur very flooding affects areas along the often in the River Adur CFMP area, coastal plain. Surface water and extreme flooding is very rare. flooding is also an issue within the Regular small flood events in the rural catchment. Serious flooding upper catchment are likely to have a caused by surface water run-off beneficial environmental effect. from the South Downs has occurred The main source of flooding in the in areas such as Worthing, Brighton River Adur CFMP area is from rivers.