Assessment of reservoir trapping efficiency and hydropower production under future projections of sedimentation in Lancang-Mekong River Basin

Sedimentation poses a significant threat to the long-term sustainability of hydropower generation. However, there is a lack of studies examining the relationship between sediment trapping efficiency and electricity generation on a basin-wide scale over time. This study aims to assess the efficiency of hydropower production in terms of reservoir sediment trapping. Modified Brune's method examined the relationship between trapped sediments in reservoirs and hydropower production, considering sediment projections for the near future. We divided the cases of existing and planned reservoirs in the mainstream river and subbasins to assess cumulative sediment trapping. Using the Lancang-Mekong River Basin as a case study, the following main findings were observed. Firstly, the existing reservoirs, under baseline conditions (2018), had the potential to trap approximately 60.9% or 82 Mt/yr of the total sediment load. Secondly, around 69% or 110 Mt/yr of the total sediments could be significantly trapped when considering the existing reservoirs and those planned according to the development plan of riparian countries. Thirdly, the hydropower production efficiency of most reservoirs in 2030 and 2040 experienced a significant decline of approximately 10%-20% and more than 30%, respectively. Therefore, sediment management is crucial for maintaining efficient hydropower production and achieving sustainable hydropower development through effective planning strategies.