Mersey Estuary Catchment Flood Management Plan Summary Report December 2009 Managing Flood Risk We Are the Environment Agency
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Mersey Estuary 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 Richard Fairclough House Knutsford Road Warrington WA4 1HT Tel: 0870 8506506 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. December 2009 Introduction I am pleased to introduce our summary of the Mersey Estuary Catchment Flood Management Plan (CFMP). This CFMP gives an overview of the flood risk in the Mersey Estuary catchment and sets out our preferred plan for sustainable flood risk management over the next 50 to 100 years. The Mersey Estuary CFMP is one of 77 CFMPs for have a 1% chance of flooding in any one year from rivers England and Wales. Through the CFMPs, we have (i.e. a 1% annual probability). We estimate that by 2100 assessed inland flood risk across all of England and approximately 25,000 properties will be at risk of river Wales for the first time. The CFMP considers all types of flooding. This is a 30% increase compared to the current inland flooding, from rivers, groundwater, surface water number at risk across the catchment. There is tidal flood and tidal flooding, but not flooding directly from the risk at several locations along the Mersey Estuary and sea (coastal flooding), which is covered by Shoreline around the Wirral peninsula, which can arise from high Management Plans (SMPs). Our coverage of surface water levels and from wave action, together with the and groundwater is however limited due to a lack of funnelling of water into the estuary from onshore winds. available information. We cannot reduce flood risk on our own, we will The role of CFMPs is to establish flood risk management therefore work closely with all our partners to improve policies which will deliver sustainable flood risk the co-ordination of flood risk activities and agree management for the long term. This is essential if we the most effective way to management flood risk in are to make the right investment decisions for the the future. To develop this plan and ensure social, future and to help prepare ourselves effectively for economic and environmental issues were taken the impact of climate change. We will use CFMPs to into account we worked with, and consulted help us target our limited resources where the risks many organisations. These included Merseyside are greatest. Development Control Officers Group, Natural England, Defra, Warrington Borough Council, Wirral Borough This CFMP identifies flood risk management policies to Council, Manchester Ship Canal Company, Natural assist all key decision makers in the catchment. It was England, NFU, English Heritage and United Utilities. produced through a wide consultation and appraisal process, however it is only the first step towards an This is a summary of the main CFMP document, if you integrated approach to Flood Risk Management. As we need to see the full document an electronic version all work together to achieve our objectives, we must can be obtained by emailing enquiries@environment- monitor and listen to each others progress, discuss agency.gov.uk or alternatively paper copies can be what has been achieved and consider where we may viewed at any of our offices in North West Region. need to review parts of the CFMP. Urban areas at risk from significant river flooding in the Mersey Estuary catchment area include Warrington, Wallasey, Birkenhead, St Helens and Hindley. In total Tony Dean across the catchment, approximately 19,000 properties Regional Director Environment Agency Mersey Estuary Catchment Flood Management Plan 1 Contents The purpose of a CFMP in managing flood risk 3 Catchment overview 4 Current and future flood risk 6 Future direction for flood risk management 10 Sub-areas 1 Glaze 12 2 Leigh (Atherton, Hindley, Tyldesley, and Westhoughton) 13 3 St Helens (and Ashton-in-Makerfield) 14 4 Upper and Middle Sankey 15 5 Warrington (Lower Sankey, Padgate & Woolston) 16 6 Widnes and Penketh 18 7 Middle Mersey Estuary (Moss Side, Ince Banks, Knowsley) 20 8 Maritime Mersey (Liverpool, Birkenhead) 22 9 Bebington (Ellesmere Port) 24 10 Greasby (Heswall & Neston) 26 Map of CFMP policies 28 2 Environment Agency Mersey Estuary Catchment Flood Management Plan The purpose of a CFMP in managing flood risk CFMPs help us to understand the • Internal Drainage Board, water CFMPs aim to promote more scale and extent of flooding now companies and other utilities to sustainable approaches to managing and in the future, and set policies help plan their activities in the flood risk. The policies identified in for managing flood risk within the wider context 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: • Landowners, farmers and will implement these approaches land managers who 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 of flood risk and how it will the plan to inform spatial be managed. planning 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 Mersey Estuary Catchment Flood Management Plan 3 Catchment overview The Mersey Estuary CFMP area open areas of water and the end The catchment has been heavily covers the lowermost 800km² of of mining pumping has led to modified for industrial purposes, the Mersey catchment, including groundwater levels rising in some and this has affected the natural most of the Wirral, and tributaries locations, this could affect surface response of river flows. The north of the Manchester Ship runoff leading to increased flooding Manchester Ship Canal, which was Canal. The area extends from and a quicker response to rainfall. built for navigation, effectively Bolton in the east, through reduces fluvial flood risk through The major tributaries are the Warrington and St Helens, and Warrington. Rivers Birket and Glaze, Sankey, includes the Mersey Estuary at Ditton, Rivacre and Dibbinsdale The CFMP area includes 19 Sites Liverpool. Brooks. The River Mersey flows of Special Scientific Interest Approximately 40% of the area is west through the area and enters (SSSIs) and the Mersey Estuary heavily urbanised. The catchment the Irish Sea at Liverpool Bay. Ramsar site. The CFMP considers is largely low lying with a few The Mersey is tidally influenced environmental opportunities and steeper areas in the headwaters of downstream from Howley Weir constraints with regards to future Glaze Brook and Sankey Brook, and (Warrington). Sankey Brook, flood risk management. in parts of the Wirral. The response Ditton Brook and some smaller to rainfall is generally slow but watercourses have a tidal influence is much faster for some of the in their lower reaches. smaller tributaries flowing through urbanised areas. Over 19,000 properties are at 1% risk of fluvial flooding, these include locations in Warrington, Wallasey, Birkenhead, St Helens, Hindley and Leigh. Flood risk management is provided by channel maintenance, raised defences and other flood defence structures such as sluice gates and pumping stations, the Manchester Ship Canal and one flood storage basin. Much of the CFMP area is underlain by the Permo-Triassic Sandstone aquifer which supports groundwater abstractions and is moderately unresponsive to rainfall events. Carboniferous coal measures underly the northern parts of the catchment. Mining River Mersey at Howley Weir, Warrington related subsidence has formed © Copyright Getmapping plc, supplied by Bluesky International Ltd 4 Environment Agency Mersey Estuary Catchment Flood Management Plan Map 1 Mersey Estuary CFMP - Main features Environment Agency Mersey Estuary Catchment Flood Management Plan 5 Current and future flood risk Overview of the current flood risk Flood risk has two components: tributaries.