CatchmentPartnerships Upper Piddle Valley Project —

Slowing the flow using Natural Flood Management techniques © Lorraine © Igar

What is Natural Flood Management? Natural Flood Management (NFM) involves working with nature to ‘slow the flow’ of water across a landscape. There are a variety of techniques that can be used, including; cross drains, earth bunds, leaky ponds, cover crops, hedges, trees, reducing compaction and grass buffers.

These techniques all work together to hold flood water upstream and allow water to release slowly back into the river, helping to reduce the frequency and magnitude of future floods in the Piddle Valley. It also helps to deliver a range of other benefits to the local environment, including improvements to water quality, biodiversity and climate change mitigation.

NFM projects can compliment the flood projects delivered by other organisations. For more information on successful projects using these methods please visit: www.stroud.gov.uk/ environment/flooding-and-drainage/stroud-rural-sustainable-drainage-rsuds-project

The Piddle Valley. Surface water and groundwater flooding

A combination of factors makes the Piddle Valley susceptible to flooding but also a good opportunity to use a sustainable approach to reducing this risk. The steep slopes fall sharply into a flat river valley. The river Piddle and the Plush Brook are fed by both groundwater and surface water. The historic modifications to the watercourses means that they are straighter, unconnected to the floodplain and so respond quickly to heavy rainfall. The combination of free draining soils of the upper valley and impeded drainage on the clays, steep slopes, climate change and the position of the villages contribute to flood events like that in February 2016.

© Environment Agency copyright and / or database rights 2017. All rights reserved; Contains public sector information licensed under the Open Government Licence Can we control groundwater flooding? What can you do to help this project?

Chalk catchments, like the Piddle Valley in are Land management practices can help to ‘slow the flow’ susceptible to groundwater flooding during wet winters or and store water; rich organic soils can hold four times following extreme rainfall events. In summer, rainfall is their weight in water. Healthy soils also retain nutrients absorbed by vegetation but in winter it recharges the aquifer and sediments are less likely to run-off fields. Land which, once full, becomes saturated leading to increased run managers across the valley can help deliver this project as off and spring activity. NFM can play an important role in wellWho as improve will theirdeliver yields and projects? productivity. managing flood risk during high groundwater conditions. Residents can attend events to discuss flood resilience The Environment Agency is helping people become aware of measures, sign up to the flood warning service and what they can do to prepared for flooding and supporting develop personal flood plans. Each parish has a flood local Flood Wardens who are working to produce a warden, they have been trained by the EA to give advice. community flood plan. The EA will be improving their understanding of how the river Piddle responds to rainfall Concreting over gardens and parking spaces reduces the with the aim of developing a more appropriate flood warning area available for rain to soak away. Avoiding this or using service. porous paving products can help infiltration and prevent Contact Lisa Milton, Environment Agency Flood Resilience surface water flooding. Team at: [email protected] For more information on catchment initiatives in Dorset please visit: www.dorsetcatchments.co.uk Lorraine Isgar Catchment Partnerships How is everyone working together to solve the problem of flood risk? Working together in the Harbour catchment will ensure that projects are co-ordinated to deliver the greatest number of benefits in the most cost effective way. Our projects aim to reduce nutrient pollution and help rivers to function more naturally for flood risk management, fish and other wildlife benefits. Some examples of projects that are already working to deliver improvements to the quality of the water environment and contributing to reducing flood risk are detailed below.

Catchment Sensitive Farming (CSF) Wessex Water Catchment Management projects

In Dorset, CSF has been working closely with farmers on all Wessex Water catchment aspects of their businesses that may have an impact on the advisers work with farmers to water environment. The Countryside Stewardship Scheme protect local drinking water provides water grants to help farmers to improve farm supplies and to improve the infrastructure such as yards and tracks that can be sources of environment. is a pollution and pathways for water flow. supply borehole for Wessex Water and they are already CSF, in partnership with the EA, has already helped farmers working with farmers to reduce © Wessex Water improve some of the tracks in the valley so that they do not nitrates in the drinking water act as pathways after heavy rain. supply.

Contact: [email protected] Many of the things advisers ask farmers to do will also be of benefit to reducing run off, erosion and soil loss. So, this Highways approach is beneficial to the farmers, the water company and the downstream communities at risk of flooding. Dorset County Council as the Lead Contact: [email protected] Local Flood Authority, has overall responsibility for flooding from What are the next steps? surface water, groundwater and ordinary watercourses and have  Farmers in the catchment will be invited to attend a produced a flood investigation meeting to discuss and develop ideas on how to report on the 2016 event. reduce the peak flows of water from their land.  Local organisations, residents and key partners will The LLFA will be project managing hold a community engagement event about flood this scheme. DCC Highways are responsible for maintaining resilience and to raise awareness of the project. the highway drainage systems to help reduce road flooding.  Catchment walkovers by volunteers will survey flows For more information please contact Becky Brookman; on roads and footpaths and landowners will check [email protected] dominant flow pathway on land.  Farm visits will take place, farmers will be given advice Wessex Water Sewerage network and funded to implement measures on their land. The infiltration of groundwater into the sewerage network is  Highways will be scheduling maintenance of the a problem for the capacity of the system. Preventing highway drainage network. groundwater getting into the network requires on-going  Wessex Water will continue to seal their sewerage work. This includes; sealing manholes, lining the pipework network to prevent infiltration into the network. and providing a safety overflow so that properties do not experience sewer flooding. Working with NFM projects, the For more information on this project, please contact: water company will protect properties, reduce customer bills and reduce emergency discharges to the natural Becky Brookman—DCC Flood Risk Engineer environment. Tim Stephens—Wessex Water Senior Adviser Contact: [email protected] Charlotte Woodford— Catchment Sensitive Farming For more information on catchment initiatives in Dorset please visit; www.dorsetcatchments.co.uk