In The efficiency, dependability, and longevity of hydropower plants are seriously threatened by high silt loads in Himalayan Rivers, which result in severe turbine abrasion and frequent operational shutdowns. The Bieri Vertical Sand Flushing System (BVFS) at the Middle Marsyangdi Hydropower Project (MMHPP) and Conventional Sediment Flushing Systems (CSFS) at the Upper Trishuli 3A Hydropower Project (UT3A) are compared in this study.

The primary objective was to test the performance of the two systems on cost, sediment removal, and the functioning of the system under the conditions within the Gandaki Basin of Nepal. The quantitative case study design was applied in the study where three years of operating data, site visit, and primary data was used to trace the downtime, energy loss and maintenance cost. The outcomes are clear that BVFS is more effective in its operation. It suffered zero forced outages in the flushing process but the CSFS experienced approximately 273.69 hours of unavailability in the same period. The water consumed by BVFS was also approximately half as much and its energy loss was almost 85 percent less than that of the routine horizontal flushing technique. With a higher initial cost of about the NPR 400 million, BVFS proved to be financially sustainable, with payback of 18.21 years the main reason being in savings on energy and maintenance annually. Generally, the results indicate that BVFS is a good alternative in the control of sediment in high-head projects in heavy sediment zones. It enables power production to be maintained even on peak months of monsoon. According to this, BVFS should be given priority during new projects having high sediment loads and old plants experiencing frequent silt related shutdowns should seriously consider retrofit.