Global Assessment of Water Stress in Karst Regions in a Changing World

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Karst develops due to the weathering of carbonate rock and results in significant surface and subsurface heterogeneity of hydrological flow and storage processes. About 7% to 12% of the Earths continental are is covered by karst regions, and approximately one quarter of the global population is completely or partially dependent on drinking water from karst aquifers. For the next decades, climate models predict a strong increase in temperature and a decrease of precipitation in many karst regions in the world. Despite these predictions, only few studies have been performed to quantify the impact of climate change on karst water resources. This is mainly due to a lack of data and inadequate representation of karst processes in existing large scale simulation approaches. The aim of the proposed junior research group is provide the necessary data and approaches to, for the very first time, assess present and future karst water resources availability at a global scale. To tackle this challenge, new research in (1) understanding and including karstic heterogeneity in hydrological models, (2) upscaling catchment based observations and simulation approaches to the global scale, and (3) comparing present and future water resources availability with water demand across the globe is necessary. The project will apply novel monitoring and analysis schemes at five test sites distributed in 5 climate regions over the world (AU, D, ES, MX, UK) to understand the effects of karstic heterogeneity of shallow surface processes in different climate regions. A newly established data base of catchment scale karst system observations will be used to apply a karst specific recession analysis to infer about the heterogeneity of groundwater storage and discharge processes in different regions in the world. From the same database and the global runoff database (GRDC), a new approach to integrate the hereby gained understanding into a large scale karst water resources simulation model will be developed. The new model will finally be used (1) to explore present and, coupled with climate simulation models, future karst water resources availability and (2) to relate it to water demands to identify present and future threats on peoples water supply.