The problem of sedimentation is extremely serious for the dams positioned on Himalayan Rivers as-they carry huge sediment load. More than 80% of annual sediment inflow comes during the monsoon. Efficient sediment management is therefore required in monsoon season to protect the economic life of the reservoirs. NHPC Limited, a Government of India Enterprise in India is maintaining 20 power stations in Himalayan region and has been successful in maintaining gross/live capacity of reservoirs of these power-stations satisfactorily by adopting different site/project specific techniques of sediment management. Drawdown flushing in small reservoirs along-with sluicing in large/medium size reservoirs, are most-adopted techniques in NHPC for sediment management in reservoir. Desilting basins/chambers have-been provided in most of the power stations to allow settlement and removal of significant portion of the-coarse sediment entering into the intake, thereby reducing the impact of big size sediments into turbine and other parts. Silt excluders/silt ejectors have also been provided in some of the projects of NHPC. Site-specific reservoir operation and flushing guidelines, prepared for every power station, have been proven-to be very helpful in preserving the reservoir capacity and ensuring smooth running of power plant.
