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Quantifying the response of karst discharge to long-term climate variations at Blautopf spring

As the second-largest and most legendary karst spring in Germany, the Blautopf spring exhibits high economic and environmental values for protection. It is crucial to understand how this karst water resource has and will be impacted by the ongoing climate change. In this study, we aim to contribute to this understanding by quantifying the response of the karst discharge to climate variations in the past 70 years at the Blautopf spring.

The historical long-term records show that the daily discharge rate at the Blautopf spring varies between 0.1 m3/s to 32.6 m3/s, with a mean of 2.3 m3/s. Due to the groundwater memory, the aquifer responds to the precipitation events with time lags. It hence leads to the difficulty to predict the timing and intensity of the peak flow of the karst spring which is often required for water management and supply. This task becomes even more challenging under climate change during which the precipitation patterns become more variable and the increasing temperature influences not only evapotranspiration but also the timing of snowmelt.

Together with the IMPART project with a focus on the water quality at the Blautopf spring, this study aims to provide a deeper understanding of how the water quantity has and will fluctuate at this site by using statistical analysis and time-series modelling approach. The research findings may help to calibrate the karst aquifer protection measures for adapting to the future climate.

Daily observed karst discharge rate (green), precipitation (blue), and evapotranspiration (pink) at Blautopf in 1954-1955