River Witham 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 Kingfisher House Goldhay Way, Orton Goldhay Peterborough PE2 5ZR 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. December 2009 Introduction I am pleased to introduce our summary of the River Witham Catchment Flood Management Plan (CFMP). This CFMP gives an overview of the flood risk in the River Witham catchment and sets out our preferred plan for sustainable flood risk management over the next 50 to 100 years. The River Witham CFMP is one of 77 CFMPs for England inundate large parts of Boston. Breaching/failure of and Wales. Through the CFMPs, we have assessed inland embankments that carry the main upland rivers across flood risk across all of England and Wales for the first the Fens pose a significant flood risk. Surface water and time. The CFMP considers all types of inland flooding, sewer flood ing can affect Lincoln, Horncastle, Grantham from rivers, groundwater, surface water and tidal and Boston. Parts of Sleaford and the surrounding area flooding, but not flooding directly from the sea (coastal could be susceptible to groundwater flood risk. flooding). This is covered by Shoreline Management We cannot reduce flood risk on our own. We will Plans (SMPs). Our coverage of surface and groundwater therefore work closely with all our partners to improve flooding is however limited due to a lack of available the co-ordination of flood risk activities. For example, information. in parts of the catchment Internal Drainage Boards The role of CFMPs is to establish flood risk management (IDBs) have an important role in managing flood risk. policies which will deliver sustainable flood risk We will work in partnership with the IDBs to agree management for the long term. This is essential if we are the most effective way to manage flood risk in the to make the right investment decisions for the future and future. We also work with many other organisations, to help prepare ourselves effectively for the impact of groups and individuals with an interest in how flood climate change. We will use CFMPs to help us target risk is managed. This includes local authorities, water our limited resources where the risks are greatest. companies, conservation bodies such as Natural England and the public. This CFMP identifies flood risk management policies to assist all key decision makers in the catchment. It was This is a summary of the main CFMP document. produced through a wide consultation and appraisal If you would like to see the full document an electronic process, however it is only the first step towards an version can be obtained by emailing enquiries@ integrated approach to flood risk management. As we environment-agency.gov.uk or telephoning 08708 506 all work together to achieve our objectives, we must 506. Alternatively, paper copies can be viewed at any monitor and listen to each others progress, discuss of our offices in Anglian Region. what has been achieved and consider where we may need to review parts of the CFMP. There are different sources of flood risk in the catchment. River flooding can occur from the River Witham, South Forty Foot Drain, Stonebridge Drain and their tributaries. This can affect Horncastle and Lincoln. Tidal flooding Paul Woodcock from the Haven overtopping the tidal defences could Regional Director Anglian Region Environment Agency River Witham 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 12 Sub-areas 1 Upper Witham, Barlings, Bain and Upper Till 14 2 Grantham, Sleaford and Ancaster 16 3 Outer Lincoln North, Outer Lincoln South and Outer Horncastle 18 4 Lincoln 20 5 Limestone Ridge 22 6 Horncastle 24 7 The Fens 26 8 Boston 28 Map of CFMP policies 30 Flat Bridge Willingham, Upper Till 2 Environment Agency River Witham Catchment Flood Management Plan The purpose of a CFMP in managing flood risk CFMPs help us to understand the • Internal Drainage Boards CFMPs aim to promote more scale and extent of flooding now (IDBs), water companies and sustainable approaches to managing and in the future, and set policies other utilities to help plan their flood risk. The policies identified in for managing flood risk within the activities in the wider context the CFMP will be delivered through a catchment. CFMPs should be used of the catchment; combination of different approaches. to inform planning and decision Together with our partners, we • transportation planners; making by key stakeholders such as: will implement these approaches • land owners, farmers and through a range of delivery plans, • the Environment Agency, who will land managers that manage projects and actions. use the plan to guide decisions and operate land for on investment in further plans, The relationship between the CFMP, agriculture, conservation projects or actions; delivery plans, strategies, projects and amenity purposes; and actions is shown in Figure 1. • regional planning bodies and • the public and businesses to local authorities who can use the enhance their understanding plan to inform spatial planning of flood risk and how it will activities and emergency be managed. 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 Witham Catchment Flood Management Plan 3 Catchment overview The catchment of the River Witham The entire CFMP area is The underlying geology of the is located in the east of England. approximately 3,000 km2 with a catchment is mudstones to the The River Witham rises south of population of around 375,000 west of Lincoln and clays to the Grantham and flows northwards, people. The catchment is east. There is a ridge of limestone through Lincoln, before turning predominantly rural. Approximately running north-south through southeast and discharging into the 90% of the CFMP area is used for Lincoln and chalk in the far Haven at Boston, and eventually arable farming and there is high north-east. Where the underlying The Wash. Map 1 shows the grade agricultural land in the Fens. rock is non-porous clay and location and extent of the River Only 3% of the CFMP area is urban mudstones, there are higher rates Witham CFMP catchment. The River and the main urban areas are of rainfall runoff, and runoff flows Witham catchment includes the Lincoln, Boston, Grantham, North directly into the watercourses. In River Brant, River Till, Fossdyke Hykeham, Sleaford and Horncastle. the areas where there is limestone Canal, Barlings Eau, River Bain and or chalk bedrock, runoff may Within the catchment there are two many other smaller watercourses. infiltrate the rock delaying the ridges of relatively high ground; The catchments of the South Forty response of rivers to rainfall and the Lincolnshire Limestone Ridge Foot Drain and Stonebridge Drain reducing peak flood flows. There roughly in the centre of the CFMP are also included in the CFMP area, is also a risk from groundwater area, north and south of Lincoln, both of which flow into Boston and flooding in these areas. Within the and the Lincolnshire Wolds in the into the tidally influenced Haven. River Witham catchment there are north-east, north of Horncastle. a number of sites designated for The downstream limit of the CFMP The remainder of the CFMP area, their environmental importance, catchment is located at Hobhole, downstream of Lincoln, is primarily including The Wolds Area of which is The Wash Shoreline low-lying, and a large number of Outstanding Natural Beauty (AONB) Management Plan (SMP) boundary. watercourses are heavily modified. and 41 Sites of Special Scientific The SMP deals with coastal flood In the low lying Fens (between Interest (SSSIs). The Wash, an management issues from The Wash. Lincoln and Boston) the rivers and internationally protected Ramsar The CFMP considers tidal flood their tributaries are embanked, with site, Special Protection Area (SPA) risk along the Haven upstream drainage influenced by a number and Special Area of Conservation of Hobhole to Black Sluice, Grand of pumping stations and the tidal (SAC) is located downstream of Sluice and Maud Foster Sluice, cycle. This means that when tide the CFMP area boundary, however which form the tidal limit on the levels are high, less water will be the River Witham and flood risk South Forty Foot Drain, River able to drain from the system. IDBs management activities can have Witham and Stonebridge have an important role in managing an effect on this area. Scheduled Drain respectively.