The vadose zone provides numerous functions within the Critical Zone, sustaining terrestrial and freshwater ecosystems and allowing various critically important environmental and hydrological processes to occur, such as aquifer recharge, evapotranspiration, solute and colloidal transport, or reaction processes that impact biogeochemical cycles. However, the spatiotemporal dynamics of these processes are still poorly understood due to multiscale heterogeneities in time and space, non-linearities within and between (coupled) processes, and difficulties in monitoring the various (a)biotic processes at play. We solicit abstracts that address these challenges. Topics of interest include, but are not limited to unsaturated, multiphase and preferential flow, solute transport, soil-water interfacial processes, novel modeling approaches, climate change-induced processes, impact of seasonal changes in vertical water content profiles, coupling between unsaturated flow and biological activity, bioremediation and biomineralization as applicable to the vadose zone. Studies based on field measurements, lab experiments and modeling approaches are equally welcome.