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Information - HS39 Dryland hydrology (co-listed in GM)
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Event Information |
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Water, Sediment and Solute transfer in ephemeral streams is constrained by the seasonal absence of surface flow, so that all material carried is deposited on the bed or held in slow-moving subsurface waters, where it may undergo chemical and/or biological transformations. The first floods of the wet season are a challenge for quantity and quality modelling because of the non-linearity of processes imposed by the drought period. These floods carry freshly eroded and dissolved material in hillslope runoff, may also re-mobilise bed material, together providing a strong immediate flush of sediment and associated nutrients, and a slower seasonal rise in dissolved material derived from subsurface waters. Although there is a continuous transition from perennially flowing humid catchments to arid areas with no flow except immediately after storms, the response of dryland catchments deserves more attention from the hydrological community and is sufficiently distinctive to justify a dedicated EGU session.
Topics which would be welcomed for this session include modelling dryland processes at a range of time and space scales, from long term water balance to flood, sediment and solute dynamics, together with field and laboratory experimental data coupled to models for intra-bed transformation processes and first flush responses. These issues are seen as important in developing understanding that is needed to support the implementation of EU water and nitrate directives for semi-arid areas, and will help to highlight the relative scarcity of instrumental records from the many dryland catchments which flow into the Mediterranean as well as in other semi-arid to arid areas.
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