Minor floods can be prevented

Multiple simple measures can be combined with great effect. Planting trees along the banks of a river can help to slow rising water, and the trees’ roots also hold the soil in place. Another option is to introduce grass-lined channels, either in the form of ditches with grass growing in them or grassy areas on a piece of cultivated land. The goal is to slow runoff and ideally channel the water to a dam where it can be stored during periods of heavy rain.

The biggest challenge is containing the water and taking pressure off the sewerage system. Several municipalities have urged their residents to disconnect their gutters from the sewerage system and reroute the water into their own yards where it can be used, for example, to water flowers. In cities, vegetation on buildings with green roofs can also help to relieve pressure from the sewerage system by storing water. Water can also be stored in small dams in forests and parks, buying time before it flows into farms and inhabited areas.

Another way to reduce the risk of flooding would be to reopen streams that have been laid with pipes. Many pipes are old and were not built to withstand current rainfall volumes. In addition to managing ever-increasing quantities of water, open streams contribute to biodiversity and create recreational spaces, particularly around the dams the streams flow into and out of.

The biggest challenge is designing a customized approach for each and every drainage basin.

“We can’t make a generic plan. Some places have high mountains and steep narrow valleys, other places are flat. This affects the bodies of water and requires different approaches.”

So says Jannes Stolte, head of NIBIO’s Division of Environment and Natural Resources. Stolte has been working in flood prevention for many years, in projects such as ExFlood, RECARE, and STIMflom