Identification of glacial meltwater runoff in a karstic environment and its implication for present and future water availability

摘要

Glaciers all over the world are expected to continue to retreat due to theglobal warming throughout the 21st century. Consequently, future seasonalwater availability might become scarce once glacier areas have declinedbelow a certain threshold affecting future water management strategies.Particular attention should be paid to glaciers located in a karsticenvironment, as parts of the meltwater can be drained by underlying karstsystems, making it difficult to assess water availability. In this studytracer experiments, karst modeling and glacier melt modeling are combined inorder to identify flow paths in a high alpine, glacierized, karsticenvironment (Glacier de la Plaine Morte, Switzerland) and to investigatecurrent and predict future downstream water availability. Flow paths throughthe karst underground were determined with natural and fluorescent tracers.Subsequently, geologic information and the findings from tracer experimentswere assembled in a karst model. Finally, glacier melt projections drivenwith a climate scenario were performed to discuss future water availabilityin the area surrounding the glacier. The results suggest that during latesummer glacier meltwater is rapidly drained through well-developed channelsat the glacier bottom to the north of the glacier, while during low flowseason meltwater enters into the karst and is drained to the south. Climatechange projections with the glacier melt model reveal that by the end of thecentury glacier melt will be significantly reduced in the summer,jeopardizing water availability in glacier-fed karst springs.