Manuscript on water ages in the critical zone currently in discussion for Hydrology and Earth System Sciences

A study on water ages and travel times in the critical zone is now out in Hydrology and Earth System Sciences Discussion. We used in this study the SWIS model that was tested at different sites in the northern latitudes in a previous investigation. We tracked the infiltrated water through the soil profiles and in the evaporation, transpiration and recharge fluxes. This way, we could derive travel times (which show how long the water takes to leave the soil via evaporation, transpiration or recharge), and median water ages (to estimate the median age of water in soil storage or the evaporation, transpiration and recharge fluxes). Our results showed for each study site, that water ages of soil storage, evaporation, transpiration and recharge were inversely related to the storage volume of the critical zone: water ages generally decreased exponentially with increasing soil water storage. These findings on the 1-D soil profile support the "inverse storage effect" as recently discussed for the catchment and hillslope scales. You can download the manuscript here.