Rivers and streams in Switzerland are put to a great deal of use and have thus become increasingly damaged. Inadequate structural diversity, a changed flow regime and fragmentation caused by obstacles along river courses make life difficult for both flora and fauna. River restoration projects are therefore urgently necessary. They provide protection against flooding, serve as recreational spaces and have a positive effect on biodiversity.
Watercourses are among the ecosystems that are most intensively used and damaged by people worldwide. Switzerland’s streams and rivers, too, are badly affected by this. The pressure exerted by utilisation, however, differs distinctly from region to region: in the Midlands, waters are primarily interfered with by residential areas, transport routes and agriculture, whereas in the Alps, intensive hydroelectric power generation is prevalent.
An obstacle every 750 metres
Fragmentation of watercourses, i.e. their artificial break-up into short sections through barriers such as structures, is extremely high in Switzerland. Worldwide, only a few countries have a similarly high degree of fragmentation: 88,000 artificial obstacles higher than 0.5m hamper the interlinkage of waters and thus their ecological function. On average, an obstacle-free run in our rivers and streams no longer amounts to more than 750m. In some rivers, the situation is even more precarious: a count of all the obstacles along the River Töss, for instance, revealed that along a reach of 60 kilometres, there are 568 artificial obstacles. Conversely, the number of natural barriers amounts to a mere 35. This has a strong adverse impact on fish, particularly small fish such as the bullhead, but also invertebrates. The distance they can move without obstacles in the River Töss is only about 100 metres.
Great need for restoration
Besides fragmentation, the lives of creatures in our watercourses are also made difficult by intensive hydroelectric power generation with its residual flow stretches and the surge regime below power stations. A majority of Switzerland’s watercourses also have an inadequate structural diversity: below 600 metres above sea level, this concerns 60 per cent of them, in residential areas even 85 per cent. However, water is all the more valuable a habitat for animals and plants, the more diverse and varied it and its immediate surroundings are.
More living space, less flooding
Restoration returns watercourses to a state that is closer to nature again. The flowing water is provided with more space, which also factors in the concerns of flood protection. Rivers and streams with sufficient space and dynamism serve as recreational areas and possess diverse structures and habitats for plants and animals. Also, bed-load discharge is guaranteed, and a minimum degree of interlinkage with the riverbank area becomes possible. In extensively used areas, space requirements must be dimensioned more generously than in more intensively used regions.
Successful restoration has a positive impact on biodiversity. As a rule, living creatures do not react to restoration immediately. However, sufficient interlinkage between rivers and streams will accelerate the recovery process.
