CHUKHA HYDRO POWER CORPORATION TSIMALAKHA. P.O. CHIMAKOTHI, BHUTAN
In the Himalayan region the rivers have a very steep bed gradient and the catchment area lies in the slopes of the hills. These give rise to flash flood, in the rivers and due to the high velocity generated as a result of steep bed gradients of the rivers, large-size boulders roll down the river beds. These rolling boulders cause considerable damage to the spillways concrete. The glaring examples were the agee-type spillways of Trisuli and landaka damaged in the first two monsoon discharges. The spillway surface along with the top reinforcement was found damaged due to rolling boulders every year, soon after the monsoon.
The Chukha Hydel Project (CHP), one of the projects in the Hinalayan range in Bhutan, has successfully tackled this problem by providing rails over the spillway glacis surface and stilling basin to protect the surface from damage by rolling boulders during monsoon. The protective measures designed by Central Water Commission and adopted in CHP are found very effective.
