Impact of Sedimentation and Bathymetry of Selected Small Reservoirs on the Priority Water-Linked Sectors in the Zambezi River Basin

Abstract

This study was conducted within the Zambezi River Basin to ascertain the bathymetry and sedimentation of selected reservoirs, evaluate their seasonal hydrological regimes, pinpoint the causes of reservoir siltation, and determine how the bathymetry and siltation impacted water-related industries and policy choices. Hydrological field measurements using a hydrographic survey boat, document studies, and interviews were used to collect the data. The 3D spatial analyst tools in ArcGIS 10.3 and hypsometric curves were used to analyze bathymetric data. Thematic analysis was used to analyze qualitative interview data. Findings indicated that sedimentation was a problematic phenomenon spatial-temporally and, it triggered a significant decrease in the storage capacities of the reservoirs. The study noted that catchments with small reservoirs were vulnerable to severe water stress, particularly from July through the beginning of the next rainy season in December. Over 90% of the local population and water-related industries were facing substantial risks of economic water shortages and may continue to face more water challenges amidst escalating climatic changes. The problem could be addressed by coping mechanisms such as alternative livelihoods, water harvesting, and water shedding. This study proposes an Integrated Water Resources Management Framework, which may help incorporate water education to bring about behavioural change against drivers of sedimentation. The proposed sediment and water resources management model serves as a multidisciplinary and transdisciplinary tool that could be used to address siltation concerns. This work has also shown the significance of bathymetric surveys of small reservoirs as a basis for policy context and regulations on managing water resources.