Cryosphere–groundwater connectivity is a missing link in the mountain water cycle

Abstract

The mountain cryosphere and groundwater play pivotal roles in shaping the hydrological cycle, yet their connectivity remains incompletely understood. Current knowledge on meltwater recharge and consequent groundwater discharge processes is more developed for snow- than glacier-groundwater connectivity. Estimates of meltwater recharge vary considerably, which is likely not only a function of inherent catchment characteristics but also of the different spatiotemporal scales involved and the uncertainties in the methods used. This hinders a comprehensive understanding of the mountain water cycle. As glaciers retreat and snowpack diminishes, the relative importance of groundwater for mountain catchment storage is expected to increase. However, shifting and declining recharge from the cryosphere may decrease absolute groundwater-related stores and fluxes, with as-yet unknown effects on catchment-scale hydrological processes. We therefore stress the need to better quantify mountain cryosphere-groundwater connectivity to predict climate change impacts on mountain water supply, supporting sustainable water resource management of dependent social-ecological systems.