River Typology for Switzerland

The typology of rivers groups the diversity of Swiss rivers according to abiotic, physiographic criteria, not considering anthropogenic impacts. They are a basis for assessment of the ecological state of rivers and represent a useful guidance for rehabilitation measures.

A great variety of surface waters with different characteristics can be found in Switzerland. The Waters Protection Ordinance covers this aspect in Annex 1 and refers to the water type in the wording of the ecological objectives for surface waters:

"The communities of plants, animals and micro-organisms in surface waters [...] shall show a diversity and frequency of species that are specific to unpolluted or slightly polluted waters of the type in question".

Accordingly, there is a need to define surface water types and to characterise the associated habitats and communities.

The revised Waters Protection Act which entered into force in 2011 requires the cantons to rehabilitate surface waters. In the coming years many rivers will be returned to a more natural state. To undertake the relevant rehabilitation measures, it is necessary to know the type of each river section and have an idea of the natural or near natural features specific to this type, as a guideline for river development.

Methodology

The river typology associates each section of the river network with a river type according to five criteria, each with two to five classes each.

Biogeographical region (Jura, Central Plateau, Northern Alps, Central Alps, Southern Alps)
Elevation (colline, montane, alpine)
Mean annual discharge (small, medium, large)
Slope (flat, semi-steep, steep)
Geology (calcareous, siliceous)

Results

In total 54 river types were defined. The main rivers of Switzerland are shown separately; special types with particular features are treated separately.

The methodology and results are described in more detail in the publication (only available in German and French, with English summary).