Design of energy dissipator for spillways in Himalayan region

Dissipation of kinetic energy generated at the toe of spillway is essential for bringing the flow velocity of the river back to normal in shortest possible distance. This is necessary to protect the river bed, banks downstream from erosion and to protect important structures from undermining. Large amount of sediments entering the reservoir is a serious problem in Himalayan region which reduces the capacity of the reservoir and damages the hydropower plants. Hence, orifice spillways are designed to pass the flood as well as flush the sediment. The energy dissipators are designed giving special consideration to sediment flushed through the spillway. Although no design procedures are readily available for designing the energy dissipators for orifice spillways, experience from the hydraulic model studies and prototype provides useful guidelines.