Groundwater quantity

The quantity of groundwater in Switzerland fluctuates during the year, but is stable in the long term.

Groundwater quantity is the total amount of water available underground in Switzerland. This groundwater is used for a variety of purposes, including water supply, agriculture, industry, geothermal energy, as well as for ecosystems. Groundwater quantity is monitored by continuous measurement of groundwater levels and spring discharges. Data are collected at around 100 NAQUA National Groundwater Monitoring sites. The monitoring sites reflect the different geological and hydrological conditions in Switzerland.

Current status reflects precipitation trends of previous months

Groundwater levels and spring discharges reflect the weather conditions at the surface, though in an attenuated form and with a time lag. Spatial and geological factors influence the intensity and speed of aquifer fluctuations.

Long periods of rainfall – especially in winter – increase groundwater recharge. In contrast, prolonged periods of drought – particularly in summer and autumn – can result in low groundwater levels and spring discharges. The groundwater quantity observed at any given time therefore reflects the weather conditions of the last few weeks or months.

Long-term trend is stable

Long-term weather patterns (temperature and precipitation) in Switzerland are often correlated with periodic, multi-year fluctuations in groundwater levels, as well as regular low- and high-level water situations that can persist over weeks and months. Within this general pattern, significant regional differences are the norm.

Recently, the dry years of 2003, 2011, 2015, 2018, 2019, 2020, 2022 and 2023 in particular have led to low groundwater levels and spring discharges. In contrast, years with above-average precipitation (e.g. 1999–2002, 2021) generally resulted in high groundwater levels and spring discharges.

The intensity of high- and low-level situations varies depending on the aquifer's location and the properties of the subsurface. For example, groundwater reserves connected to watercourses react quickly to heavy rainfall, whereas deeper groundwater reserves generally do not react to individual rainfall events and only show a small level change after a few months of prolonged rainfall or drought.