Topic | Core indicator | DPSIR | Main topic |
---|---|---|---|
Water | State |
Groundwater levels and spring discharge rates
The indicator provides a national overview of the frequency of low, normal and high groundwater conditions year on year. If the groundwater level falls more than average due to prolonged dry periods, this can cause bottlenecks in the water supply and be detrimental to ecosystems reliant on groundwater. If the groundwater level becomes extremely high due to above-average precipitation, substantial damage can be caused to landscapes and buildings. Moreover, this can trigger near-surface landslips and mudslides on sloping ground.
The dry years of 2003, 2011, 2018/2019, 2022 and 2023 resulted in an unusually high number of monitoring stations with low groundwater conditions.
Conversely, in 2001/2002, 2006/2007, 2016 and 2021, approximately one in four monitoring stations recorded above-average days with high groundwater levels and/or spring discharge rates. The floods of 2021 resulted in a unusually high number of monitoring stations with high groundwater conditions.
Based on the CH2018 climate scenarios, it must be assumed that the frequency and duration of dry periods as well as precipitation intensity and strength will tend to increase over the long term and therefore that low and high groundwater levels and spring discharge rates as defined in the indicator may occur more frequently. A long-term trend cannot yet be detected for either lower or high groundwater levels and spring discharge rates. Years with high and low groundwater levels and spring discharge rates succeed each other regularly. For this reason the indicator is not evaluated.
- Related indicators
- Flood events
At present there is no standardised indicator in international indicator systems such as the EEA. IGRAC, the International Groundwater Resources Assessment Centre, and various countries (e.g. Belgium, France, Austria) are pursuing similar approaches.
Groundwater levels and spring discharge rates are continuously recorded at the monitoring stations in the National Groundwater Monitoring NAQUA, QUANT module (some 50 FOEN monitoring stations and 50 cantonal stations). The indicator includes calculation of the annual number of monitoring stations with an above-average number of days with low, normal and high groundwater levels and spring discharge rates. The daily averages are determined at each individual monitoring station and compared with the corresponding 10th and 90th percentiles over the standard period 2001-2020. If the number of days on which the groundwater level and spring discharge rate are below the 10th percentile from the standard period 2001-2020 exceeds the average number of days over the standard period, the groundwater conditions at the monitoring station are described as ‘low’. If the number of days on which the groundwater level and spring discharge rate are above the 90th percentile from the standard period 2001-2020 exceeds the average number of days over the standard period, the groundwater conditions at the monitoring station are described as ‘high’. Normal groundwater conditions exist if the number of days below the 10th percentile and/or the number of days above the 90th percentile are below the respective average number of days over the stanadrd period 2001-2020, and/or the daily averages are between the 10th and 90th percentile.
The indicator defines the percentage of these monitoring stations with low, normal and high groundwater conditions in the relevant year.
Further information