The Impacts of Sediment Yield Estimates on a Small Reservoir in Mutoko, Zimbabwe

Water scarcity is becoming a more widespread issue due to human modification of local and global hydrologic cycles. In developing countries, land degradation, soil erosion, and its impacts on water resources are significant issues due to ever increasing water resource demands attributable to growing human populations within these areas. Small, multiple-use reservoirs are an important source of water in rural Zimbabwe. It is imperative to develop further insights into, and an understanding of, the linkage between hydrology, land use, and water resource needs in order to develop resilient water supplies for populations living in these areas. Here, a hydrologic and sediment budget was developed to inform the management of the 265,000 m3 (215 acre feet) Katoto Reservoir located near Mutoko, Zimbabwe (155 km northeast of Harare, Zimbabwe). Assuming present hydrologic and land use conditions remain the same, the entire reservoir may be completely infilled with sediment within 160 - 940 years. However, taking into account a potential 10% decrease in precipitation totals, Katoto Reservoir could become unusable within 120-160 years. Considering other factors such as population growth resulting in increased extraction values, increased evaporation due to climate change, and higher sediment yield values due to shifting land use, the useful life of Katoto Reservoir could potentially be reduced to far below the estimated lifespan of 120-160 years