From: Robin Blackstone, ENN
Published January 29, 2014 10:41 AM

Slowing down the floodwaters

Putting something called "Natural Engineering" to work in a five-year research project, Newcastle University in cooperation with the Environment Agency are discovering the benefits utilizing the land’s natural defenses to slow river flow downstream and prevent flooding. Slowing down water in anticipation of flooding events is being tested all over the world. Strategies include use of retention basins; wetlands development; levee systems and flood-walls but Newcastle University researchers directed by Dr. Mark Wilkinson are employing additional water retention strategies further up the catchment system. The Belford Burn is a small catchment system located in Northumberland, a community just south of the Scottish border. It traverses through a town called Belford flooding it regularly.

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To slow flooding waters, the team changed the natural flow pathways of the small catchment system to hinder its natural flow, manage the land's run-off and reduce flooding risks in low-lying areas. The changes also controlled some pollution by preventing phosphorous and nitrates from being washed off the land.

According to Wilkinson, "What we have shown at Belford is that by employing so-called 'soft engineering solutions' to restrict the progress of water through a catchment — disconnecting fast-flow pathways and adding storage — we have been able to reduce the risk of flooding in the lower areas and, most importantly, in the town.

"Belford is not unique and there are many other areas around the UK where these solutions could make a significant impact and potentially protect peoples' homes from some of the more severe flooding we are seeing at the moment."

The UK's Natural Flood Management program aims to reduce downstream maximum water height of a flood or peak by delaying the arrival of flooding waters downstream thus increasing preparation time downstream or natural absorbtion.

These more sustainable delay tactics include restricting the progress of water through a catchment by relying any one of the following environmental mechanisms or any combination thereof:

-Holding and storing water in ponds, ditches and field attenuation bund or embankment.

-Increasing soil infiltration through the creation of 'infiltration zones' to help water get into the soil at certain locations, such as tree belts.

-Slowing water by increasing resistance to its flow, such as planting within the floodplain or planting a riverside woodland.

-Redirecting water by channeling it away from the main flow into temporary water storage areas or buffer zones thus holding waters back until the flood peak drops.  This increases the length of the river decreasing its slope, and slowing down its flow.

Read more at Newcastle University.

Natural Engineering schematic image via Crew Centre of Expertise for Waters.

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