A scientific approach to the effect of upland restoration on flooding
02 June 2014
Three football-pitch sized plots high on the uplands of Kinder Scout could hold the key to reducing the kind of flooding that wreaked havoc in parts of England last winter.
The areas are test-beds for a six-year, £1m Making Space for Water multi-objective demonstration project in the Peak District National Park to find out whether planting heavily-eroded moorland with new vegetation can slow the flow of torrential rainfall into streams and rivers.
Facing increasingly frequent severe weather events, Defra commissioned three flood management demonstration projects in 2009 in different parts of the country to test the theory that restoring natural resilience could be an economically effective way to reduce flooding in communities downstream.
Making Space for Water in the upper Derwent Catchment, Derbyshire was one of them – its purpose being to supply essential scientific evidence for the effects of moorland restoration on which the Government can make decisions on future flood management. The need was given added urgency after 1,700 UK homes were flooded last winter, causing much human misery and economic damage.
Making Space for Water researchers, co-ordinated by the Moors for the Future Partnership and Environment Agency, presented their evidence publicly for the first time in a Symposium at the University of Manchester on May 14-15.
With the re-vegetation maturing into its third year, researchers from the University of Manchester have produced figures demonstrating that moorland planting does significantly slow the run-off following downpours.
Professors Martin Evans and Tim Allott compared the storm flow from three football-pitch sized sample areas on Kinder Scout, the highest plateau in the Peak District, now owned and managed by the National Trust.
Over the past 200 years, Peak District moorlands have been the most severely damaged landscape in the UK due to acid rain caused by pollution from nearby industrial cities, the effects of over-grazing and wildfires. The result was black, bare, eroding soil where the water ran off quickly through deep gullies.
Starting in 2009, one area of damaged moorland was left bare, one was re-vegetated with moorland plants such as heather, cotton grass, bilberry and cloudberry, and one was re-vegetated and the deep erosion gullies-blocked with small dams. What the researchers found was that re-vegetation was the key – it produced the greatest delay in water flowing off the moors after a heavy storm, although there was a smaller additional benefit from gully-blocking.
They are now conducting mathematical modelling to predict what effect this will have on rivers flowing through communities downstream.
The symposium also discussed five years of evidence from the two other Defra-funded flood management demonstration projects which have been running at the same time: the Source to Sea Project in Exmoor National Park, and the Slowing the Flow Project in Pickering, North Yorkshire.
Unlike the Peak District project, which is focused on gathering scientific evidence right at the source of the problem, the Exmoor and Yorkshire schemes are looking at large-scale practical land management – working with land managers, farmers and woodland owners to install log dams, plant trees, build earth mounds and enable farmland flood-plains.
The symposium also discussed other benefits from the schemes including purer water running into our reservoirs, increased carbon absorption to mitigate climate change and more varied wildlife.
The symposium included a field trip to Kinder Scout where the delegates saw for themselves the demonstration plots as well as some of the other Moors for the Future restoration sites and 2,000 gully blocks installed in this area.