- A water exploitation index of 20 % or above indicates the threshold of water stress.
- Water stress means an increasing risk of environmental problems and economic difficulties.
- Since 2007 the water exploitation index has been below the critical level of 20 %; in 2022 it was at 10,1 %.
- Germany is causing water exploitation in other parts of the world by importing goods. In some regions this can contribute to water stress.
The water exploitation index shows the level of water abstraction measured against the renewable water resources. The renewable water resources or the renewable water supply are presented as long-term potential water supply. The renewable water resources in Germany comprise 176 billion m³ determined for the period 1991 -2020. A use of 20 % or more of the renewable water resources is considered as water stress in international terms. Using too much water can lead to environmental problems and hinder economic development (Raskin et al. 1997). For instance, falling groundwater levels can lead to the drying out and loss of marshes and wetlands or forests can be damaged. Groundwater resources near the coast can become saline due to the penetration of seawater. Although there is no water stress in Germany on average, there are regional and seasonal differences. Precipitation is very unevenly distributed in Germany.
The indicator should have a regional and seasonal reference added in future. Illustrating the water exploitation index specifically on a regional basis (e.g. for river basins) as well as for seasons would enable to better identify potential regional or seasonal water stress.
In its Roadmap to a Resource Efficient Europe the European Commission has set a target of not exceeding the 20 % threshold value for the water exploitation index (EC 2011). In Germany the index fell from 26.3 % to 10.1 % between 1991 and 2022. The reason for this development is a continuous decline in water abstraction. In 1991 it was still 46.3 billion cubic metres (m³) while in 2022 with17.9 billion m³ it was significantly lower.
Large amounts of the water volume are being used for cooling and are then returned into lakes or rivers. If this is included in the calculation, then the water exploitation index would be considerably below 10 %. The abstractions for the energy supply are clearly declining since 2013. From 2019 to 2022 the abstractions were reduced by nearly 2 billion m³ from 8.8 to 6.9 billion m³. This clear decline is largely due to the lower use of cooling water in conventional coal and nuclear power plants. However, other water usages (e.g. cooling of data centres, hydrogen production) could lead to a renewed increase of water abstractions. Irrigation demand in agriculture is expected to increase with global warming.
In Germany itself, there is no water stress on average. However, the German economy contributes to water usage in other countries through the import of water-intensive goods. This can cause water stress in some places, depending on the local conditions (Bunsen et al. 2022, in German only).
The water exploitation index compares water abstraction with potential water resources. Calculating the water resources includes inflow from other countries and the difference between precipitation and evaporation from soils and plants. The mean of the period from 1991 to 2020 (176 billion m³) is used for calculating the index. To allow comparison with the previous climate period, the water exploitation index is additionally calculated and presented using the renewable water supply for the period 1961 to 1990 (188 billion m³). Water abstractions include those for public water supply, energy supply, manufacturing industry and mining as well as agriculture. The data is recorded and published by the Federal Statistical Office of Germany every three years (in German only). Potential water resources are determined via the water balance by the Federal Institute of Hydrology (BfG).
More detailed information: 'Wasserressourcen und ihre Nutzung' (in German only).
