Sedimentation impacts on reservoir as a result of land use on a selected catchment in Zimbabwe
2011
Mavima Godwin. A | Soropa Gabriel | Makurira Hodson | Dzvairo Wellington
A study was conducted to investigate sedimentation impacts on a reservoir as a result of land use during the 2009-10 rainfall season using hydrographic surveys and grab sampling methods at Chesa Causeway Dam in the Upper Ruya sub-catchment of Zimbabwe. Sedimentation analysis showed that the sediment specific yields at thedam were 774 t km-2yr-1 using the grab sampling method and 503 t km-2yr-1 obtained from hydrographic survey. The storage ratio for Chesa Causeway suggests that the dam has a very low storage ratio which implies that, at design stage, a substantial amount of available runoff has not been utilized. Projections based on currentsediment loading indicate that dam will be silted up in the next 11 years, with a useful lifespan of 30 years. This could be due to alluvial gold panning activities taking place on the upstream of the dam. The study has established that both hydrographic surveys and the grab sampling methods can be used for estimating sedimentation rates in reservoirs and, hence, facilitate informed decisions for Integrated Water Resources Management (IWRM). The study concluded that the lifespan of reservoirs is strongly linked to upstream landuses.
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