A flood occurs when a river bursts its banks and the water spills onto the floodplain. Flooding tends to be caused by heavy rain: the faster the rainwater reaches the river channel, the more likely it is to flood.
Here’s a new study to reduce floods ie., to plant trees around rivers that could reduce the height of flooding in towns by up to 20 percent, BBC reported.
A study for the Environment Agency concludes that trees round a feeder stream can slow the rush of rainwater and save properties from flooding. But it warns that natural flood prevention methods do not always work.
The report from the universities of Birmingham and Southampton says that, with the increasing building on flood plains and climate change increase the risk of heavy rain.There has been a rush of interest in natural methods – planting trees and creating leaky dams which attempt to delay the flow of water by creating mini-floods upstream.
The authors advised a strategic approach by taking a tributary stream to a main river then foresting the area round it, allowing the stream to make its own meanders, and letting dead wood from the forest to block the stream where it will.
A drop of up to 20 percent in flood maximum can be achieved by doing this over 25-40% of the main catchment as advised. That is because the forested area will release its water to the main stream later than water running off pastureland.
Proponents of “re-wilding” suggest turning a whole catchment to forests. But the authors say this would not work because all the water would be released at the same time. They say the strategic approach will be challenging because of the numbers of landowners involved in tackling the catchment of a whole tributary stream. The author said that foresting even 10-15% of a catchment could prevent some flooding.
Ben Lukey, a flood risk manager for the Environment Agency, said there were insufficient funds to attempt the scale of works proposed in this report, although recent changes in grants might help.
“What’s identified is opportunity for bigger impact with more strategic catchment but we have to be mindful of the possibility that if it’s not done well it could make matters worse.
“To make the scale of changes to help a big city like Leeds for Manchester – that’s a scale of ambition that would take sometime to come to pass.” The environment select committee will produce a report on flood management soon. Floods minister Rory Stewart said the government was spending more than ever to protect communities and tree planting had a role to play along with improved defences and dredging.