The final version on the manuscript on "Measuring and Modeling Stable Isotopes of Mobile and Bulk Soil Water" is now online available and can be downloaded here.

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.

We compare in our latest study soil water isotope data from suction cup lysimeter, that are limited to sample the mobile water (MW), with soil water isotope data sampled with the direct water-vapor analysis, that samples the bulk soil water (BW). We present for six landscape units at three VeWa sites that the BW isotopic compositions shows a kinetic fractionation, which is indicative for soil evaporation, but MW does not. We suggest that the relative volume of MW to BW is relevant for explaining these isotopic differences, since MW volumes are usually relatively low during periods of high evaporation. We additionally use the numerical 1-D flow model SWIS (Soil Water Isotope Simulator) to simulate the hydrometric and isotopic dynamics at the studied sites. The simulations accounting for a fast and slow flow supported the conceptualization of two soil pore domains (MW and BW) with isotopic exchange via vapor exchange. Please see the manuscript here.

Our study on the influence of forest and shrub canopies on precipitation partitioning and isotopic signatures is out in Hydrological Processes and available on Researchgate.