GIS-hydrological modelling in arid lands : a geographical synthesis of surface waters for the African Red Sea region in the Sudan
Sammanfattning: The magnitude and availability of surface waters in the arid/semi-arid Sudanese Red Sea region has been examined. In conjunction with the research objective, opinions and methodologies applied by previous researchers have been assessed. The study applied a geographical hydrological synthesis within a GIS framework. As a system with advanced geo-modelling capabilities, GIS is used to integrate spatial analysis with hydrological modelling. Broadly speaking, several levels of spatial hydrological modelling such as parameterisation, spatial integration, regionalisation and hydrologic problems synthesis and assessment have been considered. Briefly speaking, the study generated and applied four physical and stochastic models at both the catchment and regional levels. Firstly, the models and the results are evaluated using the general error term to compute the differences between the estimated areal runoff and the observed runoff in the Khor Gwob catchment. Secondly, a stochastically explained model (STD) has been selected (out of four deterministic and stochastic models) and regionalised. The validity of the catchment and regional runoff estimates in the Sudanese Red Sea region is evaluated in relation to errors inherent in spatial databases, GIS analysis, and hydrological models (e.g., the Rational Formula). Furthermore, the spatial scaling of the applied model (e.g., from catchment to a region) is also considered. Finally, it is concluded that the study area and the Sudanese Red Sea region at large, contributes an annual surface runoff that exceeds the human and animal requirements with a considerable surplus that can be used for agriculture (i.e., the region is water sufficient). Conversely, this sufficiency may be faced with the problem of spatial distribution and related storage difficulties (i.e., evaporation). With regard to human, animal and agricultural water supply, only few catchments can support the proposition of water sufficiency in the region.
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