Simulation modeling for integration of hydropower, irrigation water and water supply potentials of Lweya a river basin in Malawi

The dissertation was an attempt to get valuable information for development and management of surface water resources at river basin level in Nkhata Bay district, Malawi. The basin has 2.7 % growth rate raising the demands for water supply; irrigation and electricity. There is no valuable information to help in deciding as to how much water projects should tap from the basin without adversely affecting the environment. Lweya River basin is the district's main bank of surface waters. The basin has four meteorological stations of Mzuzu, Nkhata Bay, Chikangawa and Chintheche. The stream flows data available are for basin outlet gauge station 16F2, that ran up to 1994. Soil and Water Assessment Tool model in QGIS interface was used to simulate flows at un-gauged and targeted sites for hydrological assessment of hydropower, irrigation and water supply developments. The environmental demand was estimated using the Tennant method. The study indicated that the basin has river flow with potential to generate 2.45 megawatt hydropower. It also showed that the water can be used to irrigate 14631 ha of rice during rainy season and during dry season, 13607 ha of rice and 1024 ha of maize. The basin can also supply water for domestic and institutional usage of 0.73 m3/s for 337099 people of the catchment. Integration of potential use of the flow of the basin for the three water uses provided a framework for basin level management, planning and development of water resources projects of the district. The basin level approach is in line with the Tent decentralization program in Malawi that empowers the local district assemblies.