Present and future surface water resources availability evaluation in the middle kafue river basin, Zambia. a Scenario Analysis Approach Using WEAP Model

The middle Kafue River basin is an important economic powerhouse of the country as it supports important economic activities such as hydropower generation, extensive irrigated agriculture, industry, mining and tourism. The sub-basin is progressively faced with an inevitable situation of increasing water demand among competing users while the quantity and quality of water is diminishing. The focus of this study was to assess the present and future (up to 2020) surface water resource availability in the middle Kafue River basin, Zambia using the WEAP model. Historical hydro-meteorological data from 1999 to 2010 were used to model water supply. Water abstraction records based on water rights, were then overlaid on the modeled hydrology. Model calibration was based on Itezhi-tezhi and Kafue Gorge reservoir storages. Future climatic conditions were modeled using the Stochastic Climate Library Suite of climate variability models. Future water utilization scenarios considered were; Up-scaling hydropower generation at KGU and installation of KGL project; population growth rate averaging 4.5%; increment in irrigation of up to 25%, 5% water savings due to demand-side management practices and 5% water reuse. Model results indicated that the Kafue River has the capacity to service a 34% increase in hydropower generation at KGU, installation of a 480 MW KGL hydropower plant and all domestic water needs. However water rights based irrigation demands registers a 16% shortage under worst case scenario. 9.75% reduction in supply requirement was observed due to demand-side management and water reuse. Incorporation of water demand management strategies and basing issuance of irrigation water rights on crop water requirements can greatly improve water availability.