Restoring the Yorkshire Derwent
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Restoring the Yorkshire Derwent River Restoration Plan Final report June 2010 HASKONING UK LTD . ENVIRONM ENT 4 Dean's Yard Westminster London SW1P 3NL United Kingdom +44 (0)20 7222 2115 Telephone Fax [email protected] E-mail www.royalhaskoning.com Internet Document title Restoring the Yorkshire River Derwent Geomorphological Restoration Action Plan Document short title River Derwent Restoration Plan Status Final Report Date June 2010 Project name Favourable Condition for the Derwent Project number 9T5336 Client Environment Agency Reference 9T5336/R/303521/Lond Drafted by Dr Ian Dennis, Dr Joanna Girvan and Phil Williamson Checked by Dr Helen Dangerfield Date/initials check 01/06/10 Approved by Dr Helen Dangerfield Date/initials approval 01/06/10 River Derwent Restoration Action Plan CONTENTS Vision for the River Derwent SSSI............................................................................................ 1 1. Introduction........................................................................................................................... 3 The River Derwent Site of Special Scientific Interest ...........................................................................................3 Other interest features ..........................................................................................................................................5 Favourable condition and the need for restoration ...............................................................................................5 Aims and objectives of the River Restoration Plan...............................................................................................8 2. Key issues in the Derwent Catchment................................................................................ 9 Key issues.............................................................................................................................................................9 Fine sediment supply and deposition .................................................................................................................10 Channelisation and disconnection from the floodplain .......................................................................................13 Lack of bankside shelter and shading and overshading.....................................................................................16 In-channel structures ..........................................................................................................................................20 3. Potential solutions.............................................................................................................. 23 Potential solutions to the key issues...................................................................................................................23 Finding out more about the solutions..................................................................................................................24 Implementing solutions on the ground................................................................................................................24 Climate change implications for the Derwent .....................................................................................................24 A. Changing agricultural and land drainage management practices.................................................................25 A.1. Investigate and manage fine sediment input..................................................................................25 A.2. Selectively restrict livestock access to banks ...............................................................................27 B. Alter flood embankments...............................................................................................................................28 B.1. Remove, breach, lower or set back embankments........................................................................28 C. Enhance riparian, wetland and marginal habitats ..........................................................................................31 C.1. Tree, shrub and non-native invasive plant management ..............................................................31 C.2. Bank rehabilitation ............................................................................................................................33 D. Modify in-channel structures ..........................................................................................................................34 D.1 Remove structures .............................................................................................................................35 D.2. Modify structures...............................................................................................................................37 D.3. Alter operation of structures ............................................................................................................39 D.4. Provide a suitable fish pass .............................................................................................................40 E. Preserve existing habitats ..............................................................................................................................43 E.1. Preserve existing quality habitats....................................................................................................43 E.2. Preserve existing woody debris in the river channel ....................................................................44 4. Reach-based restoration solutions................................................................................... 46 5. Action plan .......................................................................................................................... 93 Further information sources..............................................................................................................................104 River Derwent Restoration Action Plan Royal Haskoning would like to thank the Environment Agency, Natural England and riparian landowners for their assistance in the production of this report. Figures 1.1, 2.1, 2.3, 2.4, 3.3 and 4.1 contain mapping reproduced from Ordnance Survey material with the permission of Ordnance Survey on behalf of the Her Majesty’s Stationery Office © Crown copyright. Unauthorised reproduction infringes Crown copyright and may lead to prosecution or civil proceedings. Environment Agency, 100026380, 2009. River Derwent Restoration Action Plan VISION FOR THE RIVER DERWENT SSSI The River Derwent from Ryemouth to Barmby Barrage is a lowland river unique in England and Wales. However, although designated as a Site of Special Scientific Interest (SSSI) the river and floodplain is suffering from a range of pressures resulting from both past and current management of the river and surrounding land. Our vision is to improve the ecological health of the river by restoring the mosaic of characteristic habitats needed for the wildlife to recover and thrive. The character of the restored River Derwent Our vision for the River Derwent SSSI is to work towards a river system which has: • Variable river depths and speeds along the length of the river providing areas of gravel and stony substrate and backwater for fish spawning and resting. • Shallow margins with river plants which can grow out into the river when flows are low and gently sloping river banks. • Reduced artificial impoundment (weirs, sluices. etc.) so that impacts on river function are reduced, and there is free passage for fish. • A mixture of tree cover of varied age structure providing shady spots for wildlife to shelter with a A reach of the River Derwent showing open areas for pre-dominance of open stretches for bird life in the bird communities on one bank, and more vegetation Lower Derwent valley. on the opposite bank providing shading for aquatic communities and shelter for riparian species • Floodplain used by the river at times of high flow to replenish land with sediments and reduce sediment loading within the river. An area of well-connected floodplain near Stamford An area of well-connected floodplain near Kirkham, Bridge, showing the development of floodplain showing the development of marginal habitats wetland habitats 1 River Derwent Restoration Action Plan How can we deliver restoration? • Continue positive management of reaches already in good ecological health. • Support and allow the river to recover where natural processes are already working well. • Assist natural recovery by changing management or undertaking selective river restoration works. • Remove manmade features where they damage the function and ecology of the river, whilst recognising the need to protect people and property from flooding, maintain regionally important water supplies and also the cultural, historic and landscape aspects. • Actively restore the river channel where the characteristic features of the river can only be achieved by habitat re-creation. • Reduce pressures from excessive sediment runoff. • Ensure the river is adaptable into the future to new pressures such as climate change. Keys to success • Learn from early actions and actions already implemented in other rivers under threat. • Working together as a community, with support from landowners, across the Derwent valley. • Accepting that sustainable recovery will be over longer timescales and will depend on funding. • Having a plan which is adaptable to new challenges and opportunities. •