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NEWS: Deadwood fulfils many important functions in watercourses. It serves as a habitat and food source for a variety of organisms, it leads to a reduction in the flow velocity and differentiation of the current in the watercourse and thus to the formation of near-natural structures in and around the watercourse. Studies have shown that deadwood generally leads to an improvement in structural quality and ecological status, regardless of the type of watercourse.
Nevertheless, deadwood is still removed from many watercourses as part of maintenance. The aim is to maintain the proper flow of the watercourse and prevent damage to structures or neighbouring areas. As a result, many watercourses have a low level of naturalness and biodiversity. In addition, the organisms in the watercourse are disturbed by the maintenance measures.
If deadwood is deliberately introduced or left in watercourses, it can have many advantages. For example, the maintenance effort required for pruning and clearing the watercourse is reduced in the long term. At the same time, the quality of the watercourses is improved and near-natural development is promoted. However, watercourses must be monitored more frequently, especially in autumn, to prevent undesirable developments from occurring. This is particularly important in areas where there is little space available for the watercourse or where structures need to be protected.
As a result of the Water Framework Directive and the resulting increased requirements for the quality of watercourses, a change is now taking place so that in many places more deadwood is being introduced into watercourses or left in them.
When introducing deadwood in a targeted manner, care should be taken to ensure that the material is sourced from the local area wherever possible and, if this is not possible, that wood from species typical of the area is used. The problem is that there are hardly any natural sources of deadwood left in most watercourses, meaning that non-local material has to be transported in. In addition, the elements should be fixed where space is limited in order to prevent undesirable developments. To protect narrow points in the watercourse and reduce the maintenance effort, so-called deadwood rakes can be erected in the watercourse. These usually consist of posts that are inserted into the watercourse bed. The flotsam then collects at these points and can then be fixed or reintroduced below bottlenecks, for example.
To summarise, it can be said that deadwood must still be removed from watercourses in the course of watercourse maintenance, but this should be limited to the bare minimum. The wood should not be disposed of as a whole, but rather reintroduced elsewhere. This is a very cost-effective way of improving the quality of watercourses.
Do you have further questions on this topic or need advice on the professional implementation of watercourse restoration? Our competent "Flood protection and hydraulic engineering" team from the "Water management" department will be happy to advise you.
Engineering for a better tomorrow.
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