Flood Modeling Water Appraisal and Land Reclamation: A Case Study of Gash River

Abstract

With the objective to solve Kassala Town flooding on one hand and appraise and utilize the surface and ground water potential on the other, a Correlation Model applied at El Gira, station with Kassala indicated that Kassala is continuously subjected to high floods risks. Gumbel Distribution Model and digitized map of the Gash River catchment area gave the same degree of risk. A four to five years flood return period was found to be about 600 m3/sec at Kassala Station with a discharge at El Gira about 750 m3/sec. Only 5 % of the surface water passing Kassala Town is consumed for irrigating an area of 20 000 feddans per year. It was found that the agricultural area can be reclaimed through a by pass upstream Kassala Town, making Kassala safe on one hand and using the excess water in cultivation on the other. Using HEC-HMS Model at the confluence of Khor Abu Alaga with the Gash River a hydrograph was obtained which indicated that the base flow has a maximum of 400 m3/sec. with a maximum observed surface flow of 900m3/sec. Hence the HEC-HMS Model besides indicating ground water base verified the results of the surface flow upstream Kassala gauging station obtained by both Empirical and Gumbel Distribution Models. The observed surface flow being 900 m3/sec is logical and consistent with the corresponding result obtained at Kassala which was found to be a maximum of only 750 m3/sec. Using G.I.S. available facilities contour maps were plotted, and ground water potential being both quantitatively and qualitatively excellent were found to be 3897.6 Mm3. The study recommended cooperation between Sudan, and Gash River Basin countries, as well as establishing an early warning system to reduce the risk hazards.