Climate projections for the waterworks Lindau in Saxony-Anhalt as planning basis for proactive and sustainable catchment management

The waterworks Lindau (Zerbst) are an important part of the interconnected system of drinking water supply in the region of Magdeburg, Saxony-Anhalt, Germany. The pumped water is exclusively fed by groundwater recharge. Measured groundwater heads show a continuous climate-induced decline of more than 3 meters for the last 50 years independent of waterworks management.

As basis for strategic planning of future waterworks management and optimization of the monitoring network, groundwater model based studies with climate projections were carried out. For this purpose, an approx. 1,200 km² transient groundwater flow model was set up. The present recoverable groundwater resources and their development in the catchment area until the year 2100 were modelled under changing climatic conditions. The underlying climate scenarios (RCP 2.6, RCP 4.5 and RCP 8.5) are based on the current state of global and regional climate research.

Available climate projections were statistically evaluated for the model domain. A bias correction for precipitation and evapotranspiration was applied and groundwater recharge was calculated transiently for each projection up to the year 2100 using a soil water balance model. This revealed a wide range of potential changes in groundwater recharge. The change ranges from about -35% to +50% by 2100 compared to the 1975-2020 period. The wide range results from high uncertainties of projected precipitation and spatial as well as temporal distribution patterns of precipitation.

The investigations show that in the long term further considerable changes in groundwater resources and hydrodynamics in the catchment are to be expected.