Understanding hydrological processes in drylands, from hyperarid to semi-arid regions, is a major research challenge, particularly under increasing pressure from climate change, land-use change, and water scarcity. These regions, which span over 40% of the Earth’s land surface and support more than two billion people, face complex hydrological challenges due to their high climatic variability. Their limited water resources are characterized by strong climatic variability, intermittent flows, and complex interactions between rainfall, soils, vegetation, surface runoff, and groundwater.

This session welcomes contributions that improve our understanding of key hydrological processes in drylands (such as semi-arid zones in the Mediterranean or hyperarid ones in the Sahara and other desertic areas), including rainfall variability, infiltration and runoff generation mechanisms, antecedent soil moisture controls, hydrological connectivity, transmission losses, evapotranspiration, and groundwater recharge. We particularly encourage studies addressing the episodic and threshold-driven nature of hydrological responses, surface–groundwater interactions, and the challenges of monitoring and modeling water fluxes across scales.

Given the scarcity of long-term observations in many dryland regions, notably in the Global South, we also welcome approaches combining field observations, remote sensing, novel monitoring techniques, citizen science, and modeling. Studies examining how climate and land-use changes may alter hydrological processes and water availability are especially encouraged.

By bringing together observational, experimental, and modeling perspectives, this session aims to improve process-based understanding of dryland hydrology and identify pathways towards more resilient water systems in dryland regions.