Climate change has arrived in Germany and poses new challenges for water suppliers. WatDEMAND analysed which impacts climate change will have on water demand in Germany and where new regions of water shortage might emerge.
WatDEMAND stands for Multi-sectoral Water Demand Scenarios for Germany and Estimation of Future Regions with Increasing Water Scarcity and is, like for example Vertikal and ResilJetzt!, part of the DVGW research program "Zukunft Wasser".
In WatDEMAND a top-down-approach was used to forecastwater demand in Germany until the end of the 21st century. For that, water demand was divided into the sectors households (IWW), industry (TZW) and agriculture (UHOH) to increase the detail of the results. For all sectors, the status quo was mapped first, before future scenarios were calculated using various methods. The applied methodology had to be adjusted to data availability for the different sectors, resulting in the following three approaches:
- For municipal water demand, a broad data base exists and its influencing factors are well researched. The largest influence is population size, for which forecasts have been published, which served as one of the key factors in determining future municipal water demand.
- Industrial water demand, on the other hand, does not follow any clear patterns. It is influenced by a variety of unpredictable factors and decisions made by individual enterprises have a big impact on local industrial water demands. This is why the prognoses in this sector are especially insecure. Since cooling water demand makes up for the biggest part of the industrial water demand, we based our prognoses on the development of the cooling water demands. As a second influencing factor, the development of the H2-industry was considered.
- Agricultural water demand is particularly shaped by the irrigation needs of crops. UHOH has developed a model to calculate this for two exemplary crops. The results were used to approximate the total agricultural water demand.
The determined water demand data was finally intersected with data on groundwater recharge. The ratio of local water demand to local groundwater recharge embodies the water balance of the regions under consideration. The change in this water balance from its present state to a future projection was defined as the "water balance" risk index. This index provides an estimation of whether the water balance of the studies regions will improve or deteriorate.
Finally, with the WatDEMAND+ project, the applied top-down-approach was validated using a number of control regions. To do so, we compared local and regional forecasts of water demand or water balances with our results, The identification of not only differences in the results but in the methodology as well allowed us to estimate the reliability of the results and to make recommendations for their interpretation.
It became clear that the top-down approach that we used in the project introduces significant uncertainties, as it fails to account for local intricacies, thereby rendering the results as indicative rather than precise future predictions. They are intended to serve as guidance for water suppliers in Germany, aiding them in preparing for risks associated with climate change and socio-technological shifts.
Publications
DVGW (Hrsg.); Zaun, F., aus der Beek, T., Sturm, S., Vollmer, T., Müller, B. M., Streck, T., Weber, T. (2024): WatDEMAND: Multi-sektorale Wasserbedarfsszenarien für Deutschland und Abschätzung zukünftiger Regionen mit steigender Wasserknappheit. Abschlussbericht, April 2024, DVGW-Förderkennzeichen W 202124 und W 202307 (Link to the final report WatDEMAND, in German)
DVGW (Hrsg.); Niehues, B. (2024): Szenarien der zukünftigen Wassergewinnung aus den natürlichen Süßwasserressourcen für Deutschland Überblick aus aktuellen DVGW-Studien und statistischen Daten (Factsheet on water demand in Germany by DVGW, pdf-file in German)
