Auen in der Schweiz: Von der Zustandsanalyse zum umfassenden Schutz
[Swiss flood plains: From present analysis to comprehensive protection]
Switzerland has a major responsibility for the protection of flood plains as such important European rivers as Rhine and Rhône characteristics of head- and middlewaters. The typical vegetation belongs to the following plant communities: Epilobion fleischeri,Salicion elaeagni,Salicion albae,Alnetum incanae,Ulmo-Fraxinetum. Many of the flood plains are affected by human activities (Table 1). Thereby hydroelectric production plants and gravel extraction endanger in the long run the ecosystem of the flood plains, because the rivers are lacking water and sediment. The Swiss inventory of the flood plains of national importance includes 169 objects (Fig. 1). Only 1/5 of these flood plains have preserved active dynamics. The minimal surface of a flood plain of national importance on a natural river has been defined at 20 000 m3. If the alluvial site is separated from the river by dams the minimal surface must be 50 000 m3. The 169 flood plains of national importance represent 0.26% of the surface of Switzerland. In order to preserve the flood plains of national importance, the Swiss government issued a decree which has to be implemented by 1995. This decree contains the aims of protection, restrictions in use and further measures. There are five flood plains of national importance along the High-Rhine between Bodensee and Basel. On behalf of the international commission for the protection of the river Rhine against pollution, a concept was established, how to connect these remaining ecologically important surfaces (Fig. 2). The river Rhône in the Wallis is separated by dams from its flood plain. Several times the dams broke during exceptional floods. This alluvial site is ideal for revitalization. Efforts not to repair the broken dams but to restore "life" in the floodplain, have not been successful so far.