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

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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

Mensch (Symbolbild)

World Groundwater Congress IAH 2024

Der «World Groundwater Congress» ist die wichtigste internationale Veranstaltung zu Grundwasser unter der Schirmherrschaft der «International Association of Hydrogeologists (IAH)». Zum ersten Mal seit 30 Jahren findet der Kongress wieder

Image: Robert_Kneschke,

Aussergewöhnliche Hochwasser im November und Dezember 2023

Gleich zweimal innerhalb weniger Wochen waren die West- und Nordschweiz im November und Dezember 2023 von Hochwasser betroffen. Schneefälle, gefolgt von intensivem Regen und Schneeschmelze führten vielerorts zu starken Anstiegen

Image: Pxhere, CC0