University of Twente Student Theses


Water Balance Assessment in Unguja Island, Zanzibar, Tanzania

Shaaban Haji, Haji (2010) Water Balance Assessment in Unguja Island, Zanzibar, Tanzania.

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Abstract:For sustainable development of water resource management, there is much need of conducting frequent studies; this is due to the fast growing socio-economic activities, which has impact to this precious resource. However, this is not the case in Zanzibar whereby the last extensive water resource assessment studies was done in 1994. Water balance serves to be important tool for any further hydrological study. The aim of this study is estimate the water balance components of Unguja island, Zanzibar. In fulfilling this target SWAT model was used for the first time in the island in water resource study. The 30-m resolution topography data set from ASTER GDEM was used as a basis for the construction of the model application. The DEM, soil map, land cover map and weather data were supplied to Map Window GIS interface for analytical standard technique of watershed delineation. As a result of this, 30 sub watersheds were defined. Calibrated model simulated fairly well daily stream flow s in one of these sub watersheds for six years of simulation. The daily Nash- Sutcliffe coefficients were 0.60. The results of model show fairly good fit between SWAT and previous study done by Halcrow. Model predicts surface runoff of 31.76%, 44% evapotranspiration and 24% total groundwater recharge for study area of 941 km². Although model show satisfactory results, much effort are needed in collecting monitoring data, especially for discharge data for streams.
Item Type:Essay (Master)
Faculty:ITC: Faculty of Geo-information Science and Earth Observation
Programme:Geoinformation Science and Earth Observation MSc (75014)
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