Planning for the Future River Wey Flood Risk Management Draft Strategy 2010 Public Consultation Document We Are the Environment Agency
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planning for the future River Wey Flood Risk Management Draft Strategy 2010 Public consultation document 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 Swift House Frimley Business Park Frimley GU16 7SQ Tel: 08708 506506 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. The River Wey catchment This consultation document summarises the work carried out to investigate and manage strategic flood risk in the River Wey catchment. Our preferred option is to maintain the river system and structures to meet existing flood risk standards. These standards will decrease with time due to climate change. Flood risk is the combination of probability (likelihood) and consequence (impact). We will reduce the impacts of flooding by: enhancing our flood warning and forecasting ability, influencing development planning and promoting flood proofing measures in homes. In this document the River Wey catchment has been divided in to five areas known as ‘reaches’ these are shown on Map 1. Map 1 Wey Catchment Overall Map – 5 Reaches Reach 5 Reach 4 Reach 3 Reach 1 Reach 2 © Crown copyright. All rights reserved Environment Agency. 100026380. [2008]. Environment Agency River Wey Flood Risk Management Strategy Summary 2010 1 Contents Chapter 1 Introduction 3 Chapter 2 The River Wey 5 Chapter 3 Existing flood risk and strategic options 7 Chapter 4 Options considered and their effects 11 Reach 1: Alton/Haslemere to Tilford 12 Reach 2: Tilford to Shalford 14 Reach 3: Shalford to Send 16 Reach 4: Send to Wisley 18 Reach 5: Wisley to Weybridge 20 Chapter 5 The strategy plan 22 2 Environment Agency River Wey Flood Risk Management Strategy Summary 2010 1.0 We are developing a strategy for managing the risk of flooding from rivers within the River Wey catchment in response to past flooding in the urban centres of: Farnham, Godalming, Guildford, Old Woking, Weybridge and Byfleet. Introduction This draft strategy sets out our plan for sustainable The Wey and Godalming Navigations were created flood risk management to people, property and the under Acts of Parliament and make the River environment over the next 100 years. Wey navigable from the Thames at Weybridge to Town Wharf, Godalming. This involved creation of We are able to look at flood risk management in locks, weirs, and in places, shorter channels. The a comprehensive way, by considering associated navigations were donated to the National Trust and impacts and interests of other parties. are now owned and operated by the National Trust to This strategy looks at the key issues we need to maintain navigation and channel depths. address. It outlines the options explored and details the preferred options. We have done a lot of work to Between 1930 and 1935 Surrey County Council come up with our recommendations but these are carried out the River Wey Improvement Scheme not yet finalised. You can find out how to send us (RWIS) to increase the flood flow capacity of the your comments on page 25. river whilst maintaining navigation depth. This involved removal of meanders, increasing channel This strategy will help to put into practice the Thames capacity and 14 new weirs between Godalming Catchment Flood Management Plan, which sets and Weybridge. A statutory agreement with the the strategic policies for flood risk management navigation trustees was made to ensure that the in the region. As well as this strategy, other plans new weirs would not affect navigation by siltation and policies we have developed have identified at ten key sites. Sand is removed at these annually long-term environmental improvement partnership to enable boats to navigate without grounding. opportunities that may also help to reduce flood risk. The RWIS has been handed down through various With predicted global warming and the increased organisations and we now own and are responsible frequency and intensity of storms, our environment is for these structures. We have an agreement with the likely to change. The number of flood risk areas may National Trust to operate these. increase and water shortages and dry periods are The riverside owners of channels and structures have expected to extend. These are all issues that affect a legal duty to pass flood flows, maintain the water the River Wey. levels for navigation and repair structures on the In addition to the flood risks in the catchment area, River Wey. there are many river control structures (weirs and sluices). These are used to maintain minimum water depths for navigation and control flow between the natural river and the navigation channels. Environment Agency River Wey Flood Risk Management Strategy Summary 2010 3 We have permissive powers under the to reduce the likelihood and impacts of flooding at Water Resources Act 1991, to build flood the key flood risk areas on the River Wey. management structures to protect people and This is a public consultation document and we would property. Where these are economically viable and welcome your comments by Friday 14 May 2010. government funds are available. However, funding is Our contact details are on page 25. limited and competition from other areas in the UK for this money is high. We have investigated options 4 Environment Agency River Wey Flood Risk Management Strategy Summary 2010 2.0 The River Wey is one of the larger rivers that flow into the lower River Thames, draining an area or catchment of 900 square kilometres over a length of 34km (21 miles). The River Wey There are about 1050 commercial and residential as in central Guilford, Woking and Byfleet. But properties at risk of flooding in the urban centres for development also presents the opportunity to a one percent annual probability flood event (1 in introduce flood mitigation to reduce the impact. 100 chance of occurring in any year). We have a major role in influencing development to reduce flood risk, and we are working to achieve this. The River Wey begins its journey at Alton (the North Wey) and near Haslemere (the South Wey), these two The Wey is navigable from Godalming to the River rivers combine at Tilford to form the main River Wey. Thames. Water levels, flows and distribution The Wey flows through the main urban centres of: are controlled by weirs along the river. We have Godalming, Guildford, Old Woking, Byfleet and finally produced an investment and maintenance plan through Weybridge and into the River Thames. Other for the weirs installed as part of the River Wey local centres and lower risk flood areas are in: Alton, Improvements Scheme. Farnham, Cranleigh, Rowley, Bramley and Haslemere. This investment and maintenance plan will ensure The river channel in the areas of the Wey and it’s these weirs and channels maintain their target tributaries furthest from the Thames remains mainly condition for the next 100 years. As part of our unaltered with natural earth banks. The floodplain review into the ownership and maintenance of is mostly undeveloped in these areas, except the RWIS weirs, we discussed potential transfer for a few small towns. Within the undeveloped of these to the National Trust. But concluded that floodplain there are important habitats that we aim we remain best placed to continue ownership and to protect and enhance. During summer, low flows maintenance. affect the upper and middle sections, furthest from As part of our review into maintenance activities, the Thames, meaning less water for wildlife and we looked at the existing RWIS agreement and recreation. sediment removal. We concluded that this work is In flood, the river overflows into the extensive natural principally to enable navigation and not to reduce floodplain. The majority of river flooding is shallow, flood risk. We have discussed this with the National slow-moving and mostly affects property in urban Trust who indicated that they are interested in taking areas. There are existing flood defences at Farnham, on responsibility for sand removal legally required Parnell Gardens (Byfleet) and Send Marsh. on the River Wey, as it gives them full control over works affecting their navigation interests. We will Planned developments in urban areas run the exercise our powers to remove sand for flood risk risk of increasing vulnerability to flooding, such management. Environment Agency River Wey Flood Risk Management Strategy Summary 2010 5 Other structures on the river system are owned by The Wey also supports diverse and important the National Trust, private owners or a combination fisheries identified in our Wey Valley Fisheries Action of these. We work in partnership with them to Plan, from trout in the chalk-stream headwaters to maintain and operate these for navigation and high-quality course fisheries in the lower and middle to protect habitat areas sensitive to water level sections of the river. Improved fish passage through changes. Water level management plans have been weirs would help: migration and distribution of eel, developed with Natural England to protect these brown and sea trout, salmon, lamprey and barbel. nationally important habitats. In addition to the important ecological value, the Much of the habitat in the catchment has legal Wey provides a wealth of recreational opportunities. protection with nature conservation designations. There are many sites within the study area that are These include: important for both formal and informal recreation and tourism.