Planting trees could cut flood risk

#Benefits of green #trees #urban green

Natural defences, including planting more trees, could be a solution to the country’s flooding problems, according to new research. In a study led by the Universities of Birmingham and Southampton, scientists found that planting trees could reduce the height of flooding in towns by up to 20 per cent.

They found strategic planting on flood plains could help towns downstream reduce the “peak height” of floods. But the scientists warned that natural flood defences would need to be combined with conventional prevention techniques.

The researchers studied a 100km river catchment in the New Forest, upstream of the town of Brockenhurst. In a bid to better understand natural flood defences such as tree planting, river restoration and logjams – man-made dams – the researchers used a digital model of the terrain.

Planting trees on the flood plain and increasing the number of logjams, across just 10 to 15 per cent of the total river length was found to be able to reduce the peak height of a potential flood in the town by 6 per cent once the trees had grown for 25 years. More extensive river restoration, for example in 20 to 25 per cent of the total river length, resulted in a reduction in flood peak height of up to 20 per cent.

Dr Simon Dixon, the study’s lead author from the University of Birmingham’s Institute of Forest Research, said: “We believe that tree planting can make a big contribution to reducing flood risk, and should be part of a wider flood risk management approach, including conventional flood defences.

“Tree planting would represent an extra element that helps to slow down the arrival of rain water to vulnerable locations”. The research, funded by the Environment Agency, is published in the journal Earth Surface Processes and Landforms.