Impacts on the water balance and water management
Climate change affects Switzerland’s entire water cycle. Surface and underground waters are equally exposed to changes in water quantity and water quality. The average annual runoff only changes slightly due to climate change. The greatest reduction occurs in regions which are currently still glaciated. But seasonal runoff will change significantly, with devastating consequences for water use.
Impact on the water balance
Watercourses in a changing climate
The average annual runoff only changes slightly due to climate change. But seasonal runoff distribution has already changed in recent decades. Runoff has decreased in summer and increased in winter. Climate change ensures this trend will continue.
Lakes in a changing climate
Natural lakes are important stores of water for Switzerland. Water inflow is altering due to climate change. The way in which this affects the level of surface waters depends on whether a lake is regulated.
Groundwater in a changing climate
Switzerland has very large groundwater resources but with a heterogeneous spatial distribution. This is why more local, temporary deficits in groundwater availability are already occurring during drought. This trend will increase due to climate change. Groundwater recharge will increase in winter and spring and decrease in summer and autumn.
Snow and glaciers in a changing climate
In Switzerland, melting of the glaciers, a shift of the zero-degree isotherm to higher elevations and thawing of the permafrost have been observed for some time. These developments will be exacerbated in future due to climate change.
Soil moisture and evaporation in a changing climate
The land surface forms the link between the atmosphere and water bodies and has fundamental importance in the hydrological system. As air temperatures rise, evaporation increases and the soil moisture reduces.
Water temperature in a changing climate
Climate change increases the water temperatures in watercourses, lakes and groundwater. This warming is already clearly measurable in surface waters, though the rise in groundwater temperatures is less distinctive. Higher water temperatures, especially in summer, have negative impacts on water quality and ecology.
Water ecology in a changing climate
Aquatic organisms are adapted to specific habitat conditions including water temperature, flow rate, depth, structure, chemistry etc. Specialist species can only tolerate small variations in the habitat conditions and live in ecological niches. Generalists are less discriminating and can survive in a broad spectrum of habitats.
Impact on water management
Water use in a changing climate
Water is among the most vital resources for life and the economy. We need it as drinking water, for irrigation, for energy production and in industry. Water availability and the water demand for various uses will change.
Climate change and flood protection
More frequent and intensive heavy precipitation, the climate-related increase in sediment transport and the continuing urban development in hazardous areas all intensify the risks from flood and surface runoff. Allowance is already being made for this in flood protection and urban drainage.
Water protection in a changing climate
Ecologically intact water bodies will be better able to cope with climate change and meet the diverse demands of society. It is therefore important to protect water resources from excessive abstraction and from contamination by pollutants and fertilisers. In addition, streams, rivers, lakes and groundwater must be kept in, or restored to, a state that is as natural as possible.