Abstract:
Given Uganda's per capita water availability (1004 m') as of2014, basin hydrologic modelling
can sustainably help in: planning for the anthropogenic actions and changing climate effect on
scarce water resources and reviving ecologically sensitive areas. The competing water uses within
the Lake Kochobo Sub-Catchment (LKSC) has resulted into increased water demand on River
Awoja. Previous studies within the Lake Kochobo Sub-Catchment focused on the precipitation
trend and climate change scenarios analysis, impact of land use and climate change on soil fertility
among other studies. There are no hydrologic studies evaluating the combined impacts of land use
and other human activities within the Sub-Catchment and thus affecting water allocation among
competing users. This research aimed at investigating and evaluating optimum Water Allocation
Planning in the LKSC (974 km") where unsustainable water abstractions have impacted, using
Water Evaluation and Allocation Planning (WEAP21) system. In a bid to assess the impact of
possible mitigation measures for future, the research study considered quantifying catchment water
uses in regards to their current uses and demands. This aimed at establishing a baseline for future
forecasts. The Parameter Estimation Tool (PESn was used in system calibration. Calibration
focused on reproducing daily-observed runoffhydrographs for the 2007-2017 period. To evaluate
the model performance for calibration, the Coefficient of determination (R2), Nash-Sutcliffe
efficiency (NSE), Root Mean Square Error (RSR) and Percent Bias (PBIAS) criteria were
exploited. The year 2007 was used as a base year for scenario simulations due to minimal data
gaps in the available data. The projections of the current study stretch up to the year 2050. The
study aimed at estimating the water demand within the catchment under the reference, current and
future scenarios through scenario building and analysis. As a result, sustainable management
strategies were recommended to the decision makers for implementation. It was concluded that
the basin's hydrologic behavior basing on the current and proposed future demand sites is
significant to both positive and negative scenarios. The results give an insight into the water
demand and supply implications and can guide in developing ecologically sound Sub-Catcbment
management and development strategies.
Keywords: Lake Kochobo Sub-catchment, WEAP, Water Resources Allocation, Water Demand, Uganda
