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Sponges as a nature-based solution for flood prevention

Sponges as a nature-based solution for flood prevention

By Els Otterman, Els Otterman consultancy & project management

Natural water retention by restoring wetland ‘sponges’ in the upstream sections of the river basin can contribute to flood prevention in the Rhine basin. A sponge, in this context, means water retention in floodplains, marshes and peatland areas with sponge-like soils. Relatively small interventions in small areas can make a big difference in slowing down the discharge of an entire river basin if both land use and drainage are taken into account.

This nature-based solution has the added value of providing benefits to different stakeholders in different regions, and even in different countries, along the course of the river. Apart from flood prevention, this approach restores habitats and biodiversity, provides a buffer against droughts, captures carbon, improves recreation, etc. Such a river basin, transboundary approach has proven to attract the interest of national and supra-national authorities such as the European institutions. Recently the Dutch Minister of Infrastructure and Environment has expressed her special interest in this.

The Rhine Corridor consortium of WWF, Wetlands International and a number of Dutch and German consultancies including Eurosite members Natuurmonumenten and Staatsbosbeheer (State Forest Service) is researching the feasibility of implementing this approach and hopes to start a pilot project soon. The most suitable location for this pilot would be the upstream part of the Rhine basin: the middle mountains in Germany, France, Luxemburg or Switzerland. The consortium is presently searching for funding of the pilot project.

Image: The role of drainage at the foot of the slope. On the right hand side the valley is drained by means of channels, on the left hand side the undrained situation.