The vadose zone is the unsaturated soil layer which lies between the earth surface and the groundwater table. It plays an important role within the Earth Critical Zone as a medium of transport, storage of the solutes and transfer of microorganisms to the groundwater. Within the vadose zone, the water content and the solutes concentration continuously fluctuate as a consequence of a number of processes, such as infiltration, leakage, evaporation, root water uptake and water redistribution, triggered both by natural and anthropic actions.

Due to the complexity of the environment, the variability and heterogeneity of the soil, and the non—linearity of the processes, the assessment of the fluxes through the vadose zone is still a major challenge for soil hydrologists, soil scientists, agronomists and groundwater modellers. Most of the processes remains inherently a multi—disciplinary field where experts with different background need to work together.

The purpose of this session is to bring these different groups together and to discuss cases and recent advances in monitoring and modelling approaches that aim at quantifying water and solute transport through the vadose zone, at spatial scales ranging from the local scale to the farm or small catchment ones.

Experimental, theoretical and modelling contributions on cases both from irrigated or humid climate conditions and from dryland conditions are welcomed. A focus on irrigation efficiency, leakage, groundwater contribution and water and solute fluxes modification in different agricultural stress conditions, is encouraged.