Impact of Sediment Accumulation in the Operation on Hydro Plant: A Case Study of the Nam Sana Hydropower Plant Lao PDR

The annual electricity production in Laos amounts to $1.98 billion, representing 12.8% of the country's GDP, with hydropower accounting for 80% of the total production. However, the run-of-river hydroelectric power facility has been facing issues with sediment accumulation in its reservoir. This accumulation leads to system inefficiency and corrosion of turbine components. This paper examines the impact of sediment accumulation on electricity productivity, turbine efficiency, and sediment management within the reservoir. The Nam Sana Hydropower Plant (NSN HPP) in Lao PDR serves as the case study, with data collected from 2015 to 2023. The average annual sedimentation volume is 6,459 cubic meters, which is 28.3% of the total reservoir volume, and has been removed using heavy machinery. The proposed method in the study compares monthly production before and after sediment removal, showing a 12.1% increase in production over a 30-day period. As a long-term solution to mitigate sediment accumulation, the construction of a sediment trap is suggested. This trap, with a volume of 4,000 cubic meters, can be installed by NSN HPP before the reservoir, capturing 62% of the average annual sediment accumulation.