Around 80 per cent of drinking water comes from groundwater. Groundwater is also indispensable for agriculture, industry and many ecosystems. Groundwater can act as a buffer during droughts: depending on the type and season, it accounts for 30 to 80 per cent of the total flow in Swiss watercourses.

Groundwater levels are falling and springs are drying up

As droughts become more frequent, groundwater levels are falling and springs are drying up, particularly in the Jura and the Alps. The consequences for ecosystems such as moors and watercourses can be severe. There may also be significant shortages in agriculture, industry and for households. These shortages may be exacerbated by the fact that groundwater is increasingly contaminated with pollutants, the concentrations of which can rise during dry periods.

Groundwater protection helps during droughts

‘Drought is no longer an exception, but a recurring challenge. We must actively build resilience before acute crises arise,’ states the new fact sheet from the Swiss Society for Hydrogeology of the Swiss Academy of Sciences (SCNAT), which includes experts from the water research institute Eawag. The experts propose several measures to better protect groundwater:

• Monitor, track and optimise usage: Switzerland has a good groundwater monitoring network in populated and agricultural regions. This should be expanded in outlying regions. Measurements, satellite data and models help to better track and plan irrigation and water abstraction.
• Promoting groundwater recharge: Through soil unsealing, the restoration of watercourses and peatlands, near-natural retention measures and soil-conserving agriculture, more rainwater can seep into the groundwater. These measures should be systematically integrated into spatial and land-use planning.
• Ensuring quality: Wherever possible, nutrients and pollutants should not be applied in catchment areas of groundwater abstraction points. It is also crucial to consistently enforce the existing protection zones around drinking water abstraction points.
• Joint management: The federal government, cantons, municipalities and user groups should manage water in an integrated manner on a catchment area basis, based on cantonal and national water strategies. Contingency plans are required for acute situations.

Switzerland: A groundwater treasure trove

Switzerland is rich in groundwater. This comprises a volume of 150 cubic kilometres, roughly three times the volume of Lake Constance. Just over 10 per cent is replenished annually. How drought affects groundwater depends heavily on the type of aquifer. In the Swiss Plateau, large aquifers in unconsolidated rock predominate. These respond only slowly to changes: they can buffer the effects of dry spells for a long time. Conversely, pollutants are only slowly leached out. In the Jura and the Alps, on the other hand, groundwater reserves and springs can decline rapidly and dry up during periods of drought. The filtering effect of the subsoil is also poorer. Depending on the region and the type of groundwater body, different measures are therefore required.

Cover picture: Photo: Adrian Auckenthaler