Runoff Prediction for Great Dar Fur using Statistical Methods and GIS

Abstract

The quantification of runoff and need to estimate surface water resources in wadis systems is a major field of research. Multiple regression formula for annual stream flow was established using discharge gauged stations and catchment characteristics to calculate the flows in wadis within the homogeneous region for Dar Fur States.Using Geographic Information Systems (GIS) techniques produced digital-hydrological maps and formulated a useful tool for rainfall-runoff prediction equations. Produced maps were based on elevation data provided by Shuttle Radar Topography Mission, SRTM. Hydrological mapping was done through several sub-software toolssuch as Arc hydro, 3D analysis, and ArcScence in (GIS) program. For data analysis, the XLSTAT tools in Excel program was used. The aim was to determine the best distribution of rainfall data that was used as one of the parameters in the model. After distribution in layers by using Kringing Method, together with XLSTAT tools multiple regression equations were evaluated. Three multiple regression equations were developed for the three states West, North, and South Dar Fur. They were conducted in order to relate stream flow in the hydrometric stations and independent characteristics of the catchments upstream of the stations. These characteristics were mean areal precipitation, catchment area, catchment mean slope, and stream length. These relations were summarized for three water resource regions in Dar Fur. They produced (correlation coefficient) values ranging from 0.995 to 0.999.Some stations were chosen to verify accuracy of relationship. Finally, the total annual flow was calculated for the three states based on major wadis flow. in the west Dar Fur State the available measured annual discharge forwadi Azum was(487 M.cm) but the calculateddone for two wadis Azum and Kaja were (2348 M.cm), and the measured and calculated annual discharge for two wadis Alku and Howar in North Dar Fur were (103.03 M.cm),(110.9 M.cm) respectively.and the measured and calculated annual discharge for five wadis were Nyala, Negeida, Ibra, Bulbul, and Kaya in South Dar Fur statewere(1141 M.cm),(462.801 M.cm)respectively. These calculated results were compared and discussed with previous studies in Dar Fur, and found more accurate. The study highly recommended using XLSTAT tools in Excel with High resolutions DEMs, and other method of flow estimation in catchment should be used.