jinghong reservoir, lancang river, manwan reservoir, reservoir sedimentation, Water supply for domestic and industrial purposes, TD201-500, River, lake, and water-supply engineering (General), TC401-506

The Lancang reservoirs play an essential role in China's national economy and life, and the study of reservoir siltation is of great significance to ensure its sustainable service for the nation and people. In this paper, reservoir sedimentation is quantified in stages by empirical models and theoretical methods using reservoir information and sediment data to reveal the latest status of siltation in the Lancang reservoirs. Results show that the storage capacity loss of the Manwan and Jinghong reservoirs reached 51.4% and 1.54% by 2019, which illustrates that the situation of siltation is serious. The theoretical trapping efficiency of Manwan reservoir was about 69% and the estimation result of the Brune method performed best with a value of 67.5% among the empirical methods. The Brune method was then modified with a correction coefficient and the revised Brune method can be used for the estimation of trapping efficiency in other reservoirs. Overall, this paper presents relatively accurate information for managers to understand the current state of siltation in the Lancang reservoirs, and can provide scientific guidance and data support for them to take measures to reduce sedimentation and ensure the sustainability of reservoirs. HIGHLIGHTS Phased calculation of sedimentation in the Manwan and Jinghong reservoirs is presented.; A detailed update on the sedimentation of Lancang reservoir is shown to support its sustainable service.; The Brune method performed best for estimating trapping efficiency and could be applied to other Lancang reservoirs for reference.;