Sustainable water use in Lake Edward-George Basin: A case study of River Mubuku-Sebwe sub catchments

Abstract

The need to make major decisions on sustainable water allocation in environmentally sensitive catchments in the face of high system complexity and uncertainty has aggravated water management problems across the globe. The goal of this study was to assess management options to support decision making on sustainable water use amidst the ever-increasing demands and pressures on the resource. This study was conducted in the Mubuku-Sebwe sub catchments of Lake Edward-George Basin in western Uganda. Hydro-meteorological data analysis techniques (including Rainfall-Runoff modeling) were employed to quantify the available water in the sub catchments. The Mike Hydro model was applied to allocate the water resource to developments based on different scenarios of the current (2015) and future (2040) water demand. Water use was simulated for six different uses (domestic, livestock, irrigation, hydropower, industry and ecosystem functions). The NBDSS was used to assess sustainability of the different water management scenarios/options. Sustainability was based on reliable water allocation, minimum deficits and meeting ecosystem demand/environmental flow with 2040 as the planning horizon. The analysis revealed that in 2015, the available water was 60MCM in Sebwe and 365MCM in Mubuku sub catchments. It is expected to reduce by 11% (q = 33.08 – 0.02t, R2 = 0.32) and 15% (q = 157.08 – 0.07t, R2 = 0.32) by 2040 with Q75 of 1.0m3/s and 6.6m3/s (p < 0.05) for Sebwe and Mubuku respectively and that there are seasonal water surpluses that could be put to productive use. Domestic water demand is expected to increase by 64%, livestock by 44%, hydro power by 45%, industry by 400% and irrigation by 66% by 2040. The study recommends that allocation of water should be based on the management option which prioritizes domestic and environmental water demand and allocates 90% to industry, 70% to irrigation and 60% to livestock demand. In addition, mechanisms to store surplus water at the different nodes where and when it occurs should be explored to further reduce deficits.