Moges, Semu Ayalew2019-10-092020-01-072019-10-092020-01-071998Moges, S. A. (1998). GIS-based distributed water balance model for lake Victoria basin. Master dissertation, University of Dar es Salaam. Available at (http://41.86.178.3/internetserver3.1.2/search.aspx?formtype=advanced)http://localhost:8080/xmlui/handle/123456789/563Available in print formA GIS-based distributed hydrological model that operates at a regional scale is developed for Lake Victoria basin. It operates on monthly time scale and at a spatial resolution of 10 by 10 minutes grid cells that represent the basin. The model enables, one to estimate the complex hydrologic regimes of the basin, simulate discharge from the various catchments that drain into Lake Victoria, and eventually to estimate the inflow and net basin supply of Lake Victoria. The model consists of two coupled components; a Grid-based Water Balance Model (GWBM) and a Flow Accumulation & Routing Model (FARM). The water balance model, GWBM, is developed based on the Thornthwaite and Mather monthly moisture accounting technique, and it has been used to create GIS based high resolution data sets of the major hydrological regimes of soil moisture, actual evapotranspiration and the runoff at each grid cell in the region. The GWBM uses soil-water retention properties, like the field capacity, the wilting point and the available water content that are derived from the soils & vegetation cover of the region using GIS. The flow routing model. FARM, is a multigrid, dynamic model that computes discharge through each cell within the region. It combines runoff produced by GWBM with information on network topology of the Lake Victoria, flood plain inundation & transfer rates. It is a linear routing technique applied through each grid with the assumption that the excess runoff generated by GWBM creates a subsurface storage pool over each grid cell. The coupled model has been applied to Lake Victoria basin and calibrated using measured discharges of 15 catchments for the period 1970-75. The performance of the model has been found to be reasonably good as judged by low annual & monthly percentage volumetric errors. Furthermore, long-term hydroclimatological data sets over the region have been used to represent the hydrologic regimes of the region in terms of variation of soil moisture, actual evapotranspiration and runoff. The net basin supply (NBS) has been finally computed.enMathematical modelsWater balance (hydrology)Lake VictoriaTanzaniaThesis