River Ouse Catchment Flood Management Plan Summary Report December 2009 Managing Flood Risk We Are the Environment Agency
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River Ouse 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 Ouse Catchment Flood Management Plan (CFMP). This CFMP gives an overview of the flood risk in the Ouse catchment and sets out our preferred plan for sustainable flood risk management over the next 50 to 100 years. The Ouse CFMP is one of 77 CFMPs for England and The main source of flood risk in the Ouse CFMP area is Wales. Through the CFMPs, we have assessed inland from both localised river flooding, which is made worse flood risk across all of England and Wales for the first by the influence of the tide, and some surface water time. The CFMP considers all types of inland flooding, flooding. The risk is mainly located in Lewes, Newhaven from rivers, groundwater, surface water and tidal and Uckfield. flooding, but not flooding directly from the sea (coastal We cannot reduce flood risk on our own, we will flooding), which is covered by Shoreline Management therefore work closely with all our partners to improve Plans (SMPs). Our coverage of surface and the co-ordination of flood risk activities and agree the groundwater is however limited due to a lack of most effective way to management flood risk in the available information. future. The key partners we have worked with are The role of CFMPs is to establish flood risk Natural England, Southern Water, East Sussex County management policies which will deliver sustainable Council, Lewes District Council, Mid Sussex District flood risk management for the long term. This is Council, South East Water, Sussex Ouse Conservation essential if we are to make the right investment Society, Wealden District Council. decisions for the future and to help prepare ourselves This is a summary of the main CFMP document, if you effectively for the impact of climate change. We will need to see the full document an electronic version use CFMPs to help us target our limited resources can be obtained by emailing where the risks are greatest. enquiries@environment-agency. gov.uk or This CFMP identifies flood risk management policies to alternatively paper copies can be viewed at any of our assist all key decision makers in the catchment. It was offices in Southern Region. produced through a wide consultation and appraisal process, however it is only the first step towards an 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 Ouse 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 11 Sub-areas 1 High Weald and Middle Ouse 13 2 Haywards Heath 14 3 Uckfield 15 4 Ouse Low Weald (East and West) 17 5 Lewes 18 6 The Brooks and Lower Ouse 20 7 Newhaven 21 8 South Downs (East and West)/Saltdean and Peacehaven 22 9 Seaford 23 Map of CFMP policies 24 4 Environment Agency River Ouse 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 Ouse Catchment Flood Management Plan 5 Catchment overview The River Ouse CFMP covers an area of the South Downs National Park. run-off causing the river to respond of approximately 605 square The area is particularly quickly to heavy rainfall events. The kilometres and is home to around environmentally rich and includes upper parts of the River Ouse in 165,000 people. The main urban one Special Protection Area (SPA), comparison are not as steep and centres are located either on the three Special Areas of Conservation the river flows through gently coastal plain, in towns such as (SACs), two National Nature undulating countryside. Below the Newhaven and Seaford, or in inland Reserves (NNRs) and 24 Sites of confluence with the River Uck, the towns such as Lewes, Uckfield and Special Scientific Interest (SSSIs). River Ouse is characterised by a Haywards Heath. Its unique Many of these sites support broad floodplain through which the landscape and natural beauty make important wetland habitats and river meanders down to Lewes. At it an important recreational and species sensitive to changes in Lewes the River Ouse flows through tourist destination. A significant area water level, flow and quantity. a narrow gap in the chalk hills of the of the catchment is designated as South Downs, emerging onto the The River Uck is one of the main Area of Outstanding Natural Beauty low lying Lewes Brooks where the tributaries of the River Ouse. (AONB) including the High Weald river becomes tidal as it approaches Relatively steep slopes and channel and South Downs AONBs. The South the coast at Newhaven. gradient can produce relatively rapid Downs AONB is also within the area ‘Many protected areas support important wetland habitats and species sensitive to changes in water level, flow and quantity.’ ➜ View of the River Ouse from Lewes Railway Land Local Nature Reserve. 6 Environment Agency River Ouse Catchment Flood Management Plan Map 1. Overview map of the Ouse catchment. ‘The River Uck catchment has relatively steep slopes and channel gradient, which results in rapid run-off causing the river to respond quickly to heavy rainfall events. The upper parts of the River Ouse in comparison are not as steep, flowing through gently undulating countryside.’ Environment Agency River Ouse Catchment Flood Management Plan 7 Current and future flood risk Overview of the current flood risk Flood risk is the combination of the grazing marsh, which support a Haywards Heath and Lindfield. The likelihood of a flood occurring and wide diversity of invertebrate and River Ouse is tidally influenced from the consequences when it does. We amphibious species. Flooding Barcombe Mills to Newhaven, which have assessed flood risk across the occurs from a number of sources exacerbates river flooding CFMP area using broad-scale including rivers (fluvial and tidal particularly in Lewes and Newhaven. computer modelling, though flooding), urban surface water run- making best use of existing off exacerbated by inadequate local knowledge and models where drainage, run-off from fields and appropriate. Flood risk figures take groundwater flooding. Known and Where is the risk? into account current flood defences. potential flood prone areas include Around 880 properties (residential Lewes, Newhaven, Seaford, Uckfield, The map on page 10 illustrates the and commercial) are at risk of Haywards Heath and Lindfield. consequences of a 1% annual flooding from the rivers during a probability event (1 in 100 year) There have been a number of major 1% annual probability flood event. occurring in the CFMP area. flooding events over the last century, The impact of flooding to the including the 1960, 1979, 1987, The areas with the highest environmentally designated sites is 1993 and 2000 events that affected concentration of properties at risk generally positive with benefits to the urban areas of Uckfield, Lewes, from river flooding are tabulated on many habitats, such as floodplain page 9.