Soil Loss In A Catchment And Change Of Storage Volume In A Hydropower Reservoir Case Study: Lom Pangar Hydroelectric Dam, East Region Cameroon
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For many purposes such as water supply, irrigation flood control and hydropower production, many reservoirs are built throughout the planet. However, because of the processes of erosion and sedimentation, these infrastructures are facing a big problem of progressive reduction of their storage capacity. Consequently, a good knowledge of the change of storage for proper planning and management is very important. The wellknown Universal Soil Loss Equation (USLE) was used to evaluate the gross erosion in Lom Pangar catchment and the sediment delivery ratio relation used to evaluate the quantity of sediment that effectively reach the outlet of the catchment. To evaluate the soil loss from the watershed using USLE model, the topographic map of 30 m x30m resolution was used in ArcGIS software to generate the LS factor which average was 3.64. To determine the erodibility factor, the FAO map was used to generate different soil type, present in the catchment and come up with different mineral component. The average erodibility was evaluated to be 0.024 t. ha.h (ha MJ mm). The roose (1980) equation and the average annual rainfall were used to generate the erosivity factor which average for the watershed was 14 509.55 MJ?mm?ha?1 h?1 yr?1. Concerning the cover factor, the MODIS table and the classified map were used to come up with an average C factor of 0.08. In order to avoid underestimating the soil loss, the practice factor was considered to be one. Following the determination of different factors, the gross erosion was developed to be 202.8 million ton of soil per year with an average of 28.392 million ton per year that effectively reach the outlet. On the quantity that reach the outlet, the Brune (1953) Sediment trap efficiency was applied and 50.7% of the storage volume is filled after 140 years. The impact of land use change on erosion was studied too. That for the year 2015 and 2017, and main result was 101.4 t/ha/year of soil lost in 2017 instead of 28.4 t/ha/year in 2015. Based on the construction design parameter, the useful life of reservoir is generally 100 years; per consequent, it can be retained from our result that the sediment is not a major problem in Lom Pangar reservoir.