Global groundwater recharge modeling in karst with explicit consideration of land cover and snow and glacier storage

Estimating karst water resources at a global scale represents a key step towards enhancing groundwater management. Although recharge estimations at global scale exist, the special karst features leading to different recharge processes, in particular the preferential flow path, have not been adequately accounted for. Representing these special recharge processes is crucial for realistically quantifying recharge in karst regions. In this study, we present a new version of a global karst recharge model and the estimation of its model parameters using multiple observations. The updated model includes a new routine to consider eight land cover types for calculating evapotranspiration, interception and infiltration, as well as a new routine to account for snow and glacier melt. To prepare parameter estimation, six karst landscapes are defined based on the properties of karst grids (spatial resolution of 0.25°). For each of these landscapes, model parameters are found separately using a Monte Carlo uncertainty estimation framework and observations from the international soil moisture network (ISMN) and actual evapotranspiration observations from FLUXNET. With the new calibration, the updated model provides more precise estimates of groundwater recharge in athe karst regions of the world. It will therefore serve as a too  to improve water management in karst regions and identify areas potentially suffering from water shortage.