Reducing the risk of flooding
It rains a lot on the moors of the Peak District and South Pennines. The unique plants that grow on healthy blanket bogs slow the flow of rain from the moors to the towns and cities below. Mollie from Moors for the Future Partnership carries out an experiment on Bleaklow in the Peak District to show us how these landscapes can reduce the risk and severity of flooding.
Blanket bogs are worth protecting because they can help reduce the risk and severity of flooding.
Watch Blanket Bogs are Worth Protecting – Reducing the Risk of Flooding on Youtube
Blanket bogs need protecting to reduce risk of flooding
When blanket bogs are in poor condition, particularly where peat is exposed, rain water flows quickly off the moors. Bare peat is very poor at absorbing water and water runs easily over its smooth surface. Furthermore, due to extensive erosion of the soil over time, drainage gullies have developed on many of our moors, providing perfect conditions for water to be funnelled into streams and rivers – in other words, creating perfect conditions for flooding.
Re-vegetating areas of bare peat and blocking erosion gullies and drainage channels (known locally as grips) helps to reduce the rate and amount of water flowing downstream during high rainfall events. Replanting the uplands with moorland species including sphagnum mosses provides that essential surface roughness to lower the rate at which water leaves the moors. Blocking gullies and ditches with a series of mini dams holds water back.
Sphagnum moss can absorb up to 20 times its weight in water. So during the summer, when it rains heavily following dry weather, healthy blanket bogs can absorb some of the water. This keeps water on the hill at source for longer, reducing the likelihood and impact of flooding in the watercourses below.
Useful Resources: www.moorsforthefuture.org.uk