Browsing by Author "Wagner, Sven"

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    Water balance in a poorly gauged basin in West Africa using atmospheric modelling and remote sensing information
    (2008) Wagner, Sven; Bárdossy, András (Prof. Dr. rer. nat. Dr.-Ing. habil.)
    Sustainable water resources management under increasing water demands and changing climate conditions is a central, socio-political challenge, in particular in climate sensitive regions. Decisions in sustainable water resources management require scientifically sound information of the current water resources and fluxes and future water availability. The first objective of this work is to provide estimations of the current water resources and fluxes in a poorly gauged basin, the White Volta basin in West Africa. This is a central task to support water management authorities and stakeholders in operational irrigation, water supply and running hydro-power strategies. To allow investigations in ungauged or poorly gauges basins, these instruments and methods should be applicable world wide, cost-effective and preferably public domain. In poorly gauged basins without automatic data recorders and online transmission other meteorological data sources for near real time estimations of the terrestrial water balance have to be used to overcome the temporal delay and/or the insufficient spatial resolution. Therefore, a joint atmospheric-hydrological modelling system with MM5 and WaSiM is developed which is able to provide near real time water balance estimations within 48 h. Additionally to meteorological modelling results and observation data, a TRMM product, which is available with approximately one month delay, is applied as precipitation data source. Besides meteorological driving data, land surface properties are essential input data for distributed hydrological modelling. Land surface properties information is usually taken from standard literature values and incorporated into hydrological modelling through tables depending on the land use. The second objective of this work is to increase the level of detail in the spatial and temporal dimension of land surface properties in hydrological modelling using satellite derived land surface properties and to investigate the impact on hydrological modelling results. In this study, products of the MODerate resolution Imaging Spectroradiometer (MODIS) remote sensing system for albedo and leaf area index LAI are imported into the hydrological model and investigated. For sustainable decisions in water resources management, additionally to the modelling result itself, the reliability or uncertainty of the result has to be quantified. Due to the fact that the spatial variability of rainfall is often termed as the major source of error in investigations of rainfall-runoff processes and modelling, the propagation of uncertainties, resulting from the calculation of areal precipitation from point measurements in water balance estimations, are investigated as third objective. Therefore, different spatial interpolation methods, including external drift kriging, for areal precipitation are applied, and their impact on water balance estimates is analysed. Furthermore, geostatistical simulations using the turning band method for areal precipitation are performed in order to investigate the propagation of uncertainties in water balance estimations. These results provide ranges of the temporal and spatial distribution of water balance variables as consequence of uncertainties from the calculation of areal precipitation from station data.