Thirty years of river restoration in Switzerland: implemented measures and lessons learned

摘要

In the age of climate change and ecosystem degradation, governments realise more and more that it is crucial to protect ecosystem health, to preserve water resources and to maintain flood protection. Therefore, several countries, among those Switzerland, have implemented laws to make the restoration of riverine ecosystems a legal obligation. In Switzerland, restoration projects were implemented as early as 1979, prior to these laws coming into force. For this article, 848 Swiss restoration projects, implemented between 1979 and 2012, were investigated, spanning a total of 307 river kilometres. No correlation was found between the geographical distribution of total restored lengths in a way that larger cantons performed more restorations. Neither was there a correlation between the total restored length and the canton's population density or financial status. Restoration activities increased steadily after 1992, with most restorations being reported for the years 2004, 2005 and 2009. The average restoration rate was 9.8 km per year, ranging between 0.5 km in 1979 and 23.9 km in 2004. Restoration measures were very diverse, ranging from measures that directly affected the wildlife, e.g. by providing habitats, to measures which indirectly enhanced conditions for the ecosystem, such as water quality ameliorations. Data regarding success evaluation was only available for 232 of the 848 projects, making it difficult to state whether the implemented restoration projects reached the intended objectives. Over the next 80 years, a further 4,000 km of Swiss rivers will be restored, requiring a restoration rate of 50 km per year, which, according to the data, is an achievable goal.