Motivation and objectives: The evaluation of different options for water management in semi-arid and arid regions requires profound knowledge of hydrological processes of regional relevance (e.g. occurrence of surface runoff, dynamics of wetland areas, hydrological connectivity, evaporation characteristics) as well as the mechanisms and effects of the water management (e.g. water retention and sedimentation in reservoirs, water demand of irrigation systems, efficiency of water transfer schemes, control of multi-functional systems). These areas are characterized by a strong seasonality of the discharge regime and thus particularly dependent on the storage of water in reservoirs to bridge periods of low or zero discharge and to secure water supply throughout the year. However, erosion of over-exploited land surfaces and sediment input into reservoirs greatly reduce the safety of the water supply. The aim of WP3 is the transfer of the seasonal meteorological forecasts (WP1) to the key variables in regional water management in semi-arid areas: discharge, reservoir capacity, soil moisture and sedimentation in rivers and reservoirs.
Methods: These aspects should be specifically adapted to semi-arid and data -scarce regions in a multi-scale hydraulic modelling system. Moreover, the system should be easily applicable for seasonal forecasts. As a basis, the large-scale hydrological model mHM will be utilized. To specify and further analyze this information, the regional water distribution and sediment transports for hydro- and sedimentological process approaches are implemented in the model system WASA-SED for semi-arid conditions. These are used by the information supplied by the model mHM to process and prepare it for subsequent aspects as sediment transport and deposition of sediments in reservoirs. Additionally, approaches for the above-mentioned water management schemes will be implemented to obtain results relevant for water management and ecosystem issues. The quantification of sediment transport in rivers and the sedimentation in reservoirs (remote sensing-based and model-based) provide a basis for both, the anticipatory seasonal reservoir management as well as a medium to long -term assessment of ways to achieve a sustainable reservoir use. The utilization of the hydrological modelling system is based on innovative and globally available data-sets, such as satellite-based information on water levels of major rivers and reservoirs (WP1: Jason 2&3, SARAL/ALTIKA, Sentinel3), soil moisture (ESA CCA, SMAP, SMOS), as well as anomalies of the total water storage for very large areas (GRACE).
This project was financed by the German Federal Ministry of Education and Research under the financial assistance agreement No 02WGR1421.