Previous Sessions at the EGU have showed that there were many active researchers in dryland hydrology, world-wide. There is a great deal of empirical work, but it is clear that many aspects of hydrological response are less well understood than for humid areas. This knowledge gap results partly from the relatively sparse measurement networks, the higher complexity of the hydrological processes, and the common assumption (e.g. in the EU Water framework Directive) that arid and semi-arid rivers contribute little to continental or marine water quality. There is, moreover, a lack of simple conceptual and/or operational models for dryland areas, and much forecasting is based on inherently unsuitable adaptations of humid-zone models.
We would like to encourage contributions on all aspects of the dryland hydrological cycle, including the spatial and temporal distribution of precipitation, evapotranspiration, runoff and groundwater recharge; the response of ephemeral streams to storm events including seasonal variations in dominant flow pathways and surface/subsurface connectivity. We would also welcome analyses of experimental catchment data, particularly if this addresses some of the outstanding theoretical and practical issues; and approaches to modelling hydrological behaviour in dryland areas.