North Kent Rivers 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 North Kent Rivers Catchment Flood Management Plan (CFMP). This CFMP gives an overview of the flood risk in the North Kent Rivers catchment and sets out our preferred plan for sustainable flood risk management over the next 50 to 100 years. The North Kent Rivers CFMP is one of 77 CFMPs for urban areas including the Medway Towns, and some England and Wales. Through the CFMPs, we have villages on the Isle of Sheppey. assessed inland flood risk across all of England and We cannot reduce flood risk on our own, we will Wales for the first time. The CFMP considers all types of therefore work closely with all our partners to improve inland flooding, from rivers, groundwater, surface the co-ordination of flood risk activities and agree the water and tidal flooding, but not flooding directly from most effective way to management flood risk in the the sea (coastal flooding), which is covered by future. The key partners we have worked with are Kent Shoreline Management Plans (SMPs). Our coverage of County Council, Upper and Lower Medway IDB, surface and groundwater is however limited due to a Medway Unitary Authority, Maidstone District Council, lack of available information. Swale District Council, Tandridge District Council, The role of CFMPs is to establish flood risk management Sevenoaks District Council, London Borough of policies which will deliver sustainable flood risk Bromley, Gravesham District Council, Mid Kent Water, management for the long term. This is essential if we London Borough of Bexley, London Borough of are to make the right investment decisions for the Greenwich, Dartford Borough Council, Thames Water, future and to help prepare ourselves effectively for the Tonbridge & Malling Borough Council, Sutton & East impact of climate change. We will use CFMPs to help us Surrey Water, Natural England, South East Water, target our limited resources where the risks are greatest. Southern Water, Surrey County Council, Darent River Preservation Society and Canterbury City Council. 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, if you produced through a wide consultation and appraisal need to see the full document an electronic version process, however it is only the first step towards an can be obtained by emailing integrated approach to flood risk management. As we [email protected] or alternatively all work together to achieve our objectives, we must paper copies can be viewed at any of our offices in monitor and listen to each others progress, discuss Southern Region. what has been achieved and consider where we may need to review parts of the CFMP. The main sources of flood risk in the North Kent Rivers CFMP area are localised river flooding along the Toby Willison Darent, Shuttle and Cray and surface water flooding in Regional Director, Southern Region Environment Agency North Kent Rivers 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 Shuttle and Upper Cray 13 2 Upper Darent and tributaries 14 3 Dartford and Ebbsfleet 15 4 North Kent Marshes 16 5 North Kent Downs 17 6 Medway Tributaries 18 Map of CFMP policies 19 4 Environment Agency North Kent Rivers 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 North Kent Rivers Catchment Flood Management Plan 5 Catchment overview The main characteristics of the a ridge of high ground, the North (Chatham, Rochester and North Kent Rivers CFMP area are Downs, running east to west, Gillingham). These towns, as well as different topography and geology, separating the upper and lower many smaller towns and villages, with significant groundwater reaches of both the narrow, steep contribute to the regional economy components in the headwaters and River Darent and the low flat River and are focal points for many of the narrow valleys of the chalk block. Medway. visitors to the region every year. More dense river networks, broad Important issues are the availability The area is home to around valleys and active floodplains where of water resources, the urban 880,000 people and includes geology and soils are impermeable. development of Thames Gateway several important urban centres, The tidal influence has a major and the environmental designations which are mainly concentrated near bearing on the character of the of the Marshes and the North Downs. the estuaries. These include lower parts of the River Darent and Dartford, Gravesend, Sittingbourne, the marshes that border the Faversham, and the Medway Towns estuaries. The catchment is split by ➜ High flood waters at Church Street Bridge, Shoreham, Kent. 6 Environment Agency North Kent Rivers Catchment Flood Management Plan Map 1. Overview map of the North Kent Rivers catchment. © Crown Copyright. All rights reserved. Environment Agency, 100026380, (2008). ‘The North Kent Rivers catchment is split by a ridge of high ground, the North Downs, running east to west, separating the upper and lower reaches of both the narrow, steep River Darent and the low flat River Medway’ Environment Agency North Kent Rivers 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 scale computer modelling, though The map on page 10 illustrates the likelihood of a flood occurring and making best use of existing distribution of the flood risk from a the consequences when it does. The knowledge and models where one in 100 year river flooding event main sources of flood risk in the appropriate. Flood risk figures take and one in 200 year coastal North Kent Rivers area are from river into account current flood defences. inundation in the North Kent Rivers flooding along the Darent, CFMP area. Historical records show intense combinations of fluvial and surface storms have caused flooding since The areas with the highest water flooding in the Cray and 1897. The main river flooding occurs concentration of properties at risk Shuttle sub-area, localised flooding either along the Darent or in the from river flooding are tabulated due to the poor passage of water and Cray/Shuttle sub-area, this flooding on page 9. blockage of outfalls by high tide along is caused by high rainfall in the coast (tide-locking). Floods bring conjunction with an impervious consequences to people, properties catchment, for example it is already and the environment. The risk of How we currently saturated by rain. Intense non-tidal flooding in the CFMP area manage the risk thunderstorms are the main cause is small compared to the risk of tidal of flooding in the smaller, steeper There are considerable tidal defences flooding, however, all floods can and more urbanised Cray and in the North Kent Rivers catchment cause significant disruption and Shuttle catchment, and these tend but these are not discussed in this stress. We have assessed flood risk to happen in the summer.