Switzerland is rich in groundwater. Groundwater resources occur almost everywhere, both in unconsolidated sediments and fissured or karstified bedrock. They represent an important natural and economic resource.
Groundwater is generally plentiful in Switzerland. It fills the voids in the subsurface, is recharged from precipitation and river water and is a component of the water cycle. The subsurface in Switzerland contains some 150 km3 (150 billion m3) of water, making groundwater the largest water reservoir in the country, together with the lakes. Over 10% of this, some 18 km3, is renewable annually and could theoretically be extracted sustainably, i.e. without a permanent impact on the environment. However, the amount of groundwater that is actually usable is much smaller due to the intensive land use in large parts of Switzerland and associated conflicts of use.
Important resource for people and nature
Groundwater is used for various purposes, the main one being as the resource for our most essential requirement, drinking water. Switzerland relies on groundwater for 80% of its public water supplies. About half of this requirement is extracted from wells and the other half from springs.
Groundwater is now also increasingly used for heating and cooling in the energy sector; it is the basis for conservation of ecologically important wetlands and is a distinctive feature of the landscape in the form of countless springs, cave streams and watercourse feeders.
Different types of aquifer
The subsurface is both a reservoir and a filter for water. Depending on the geology, different types of aquifer occur, termed unconsolidated, fissured or karst, with specific water yield, storage capacity and flow rate characteristics. These and the soil cover influence both the quality and the quantity of the groundwater, such as its natural protection against pollutants or its availability in periods of drought.
The Swiss groundwater resources which are most important for water supply management are located in the unconsolidated sediments of the river valleys on the Central Plateau and along the large alpine valleys. The karst regions of the Jura and the Alps, with their large springs, are also important groundwater resources. The porous and fissured molasse rocks on the Central Plateau and the fissured crystalline rocks of the Alps form locally important shallow groundwater reserves. Deep groundwater flow systems also occur in the bedrock and can feed thermal and mineral springs.
Resource under pressure
Although the requirement for drinking and service water in Switzerland currently represents only about 7% (1.3 km3) of the groundwater yield available annually for sustainable use, such is the pressure on the resource that this potential cannot be anywhere near fully exploited. Some groundwater resources fall short of the required quality levels, particularly in urban areas and regions of intensive agricultural use, and increasing urbanisation is making it much harder to protect groundwater wells. In addition, local supply shortages can occur in some groundwater resources during periods of drought. Groundwater must therefore be sustainably managed and be protected to guarantee its availability and multiple functions. To achieve this, the FOEN records and evaluates the status and trend of groundwater quantity and quality nationally as part of the NAQUA National Groundwater Monitoring.
Last modification 09.07.2019