Starting with the origin of Switzerland's abundant water resources, the high amount of precipitation in the Alps, the web portal explains relevant hydrological, water management, social and environmental aspects of water.more

Image: thomasfuer, photocase.demore


The great unknown

Although at least 80% of drinking water comes from groundwater (see Water Use and Consumption), the renewal of this resource is not well understood. An unknown portion of the effluent from the water balance feeds the groundwater, while the same amount of groundwater feeds back into watercourses (the total water balance doesn’t change). It is assumed (Sinreich et al. 2012) that only about 10% of the theoretically usable groundwater in Swiss reservoirs can be sustainably replaced (equivalent to about a third of the annual rainfall, or 18 km3). The natural replacement of the groundwater depends on the aquifer type (see Glossary). Water can linger for a long time in different aquifers. This time is determined by the underlying geology (how well can the (rain)water seep into the aquifer?), by the size of the groundwater resources, and by the presence of watercourses. The residence time of groundwater can be between a few months (along rivers such as the Aare) to over 10 years (limestone areas like those found in parts of the Alps and Jura mountains). In the case of heavy precipitation in karst areas, the rivers react quickly, although the majority of the water flows away underground before emerging at a source. Thus, all groundwater is not well mixed. Imagine a wet sponge: if more water is introduced, some of the water already in the sponge is pressed out.

Events, News, Publications

beech stream forest water
Erste nationale Analyse zum Zustand der Gewässer zeigt Fortschritte und Defizite auf

Eine Vielzahl von Seen, Bächen und Flüssen sowie das Grundwasser bilden zusammen das Gewässersystem der Schweiz. Zum ersten Mal ist dieses System nun in seiner Gesamtheit beurteilt worden. Das Bundesamt

Image: M. Bolliger
maple stream
Bäche, Flüsse, Seen und Grundwasser unter der Lupe

Unsere Gewässer erfüllen verschiedenste Zwecken: Sie liefern gutes Trinkwasser in genügender Menge, bieten vielfältigen Lebensraum für Tiere und Pflanzen, ermöglichen die nachhaltige Produktion von Strom aus Wasserkraft oder laden ein

Image: M. Bolliger