ESTIMATION OF DESIGN FLOOD AND GLOF FOR A HYDROPOWER PROJECT IN THE HIMALAYAS

Abstract

In Indian Himalayas, many hydroelectric projects are now under construction due to the availability of a perennial water source and a natural head for hydropower generation. Hydropower plants often require significant investments, design lifetimes, and lengthy amortization. These plans recognize GLOFs as a significant climate change-related flood to be considered for the safety of River Valley Projects. The snow-fed catchment area of these projects has many glacial lakes, and there is a high likelihood of breaching for lakes located at the glacier's snout. In general, potentially dangerous lakes are located near the end of a glacier in the lower part of the ablation area. A large mother glacier can create potentially hazardous lakes. These moraine dams could likely breach due to piping or overtopping due to their porous soil content inside dam body. A sudden discharge of significant magnitude could endanger the safety of the downstream HE hydroelectric project. It is suggested, the glacial lake outburst flood (GLOF) and the inflow design flood be simultaneously considered while assessing the spillway capacity of new hydropower projects to ensure that they are hydrologically secure. Bajoli-Holi Hydroelectric Project, located on River Ravi is studied to analyze its spillway capacity considering both GLOF and Inflow Design flood. BIS published the guidelines for fixing spillway capacity of dams based on its gross storage capacity and hydraulic head. The hydrology of a particular basin or project undergoes certain changes due to factors such as climate change, urbanization, deforestation, soil erosion, a heavy spell of short-duration rainfall, etc. With the aid of the most recent methods, including hydrodynamic modeling and a hydro meteorological approach, the design flood and GLOF for the dam have been evaluated in this study. Arc-GIS have been used for catchment delineation using ASTER DEM. Different breaching parameters for conducting a sensitivity analysis have been employed in the GLOF study using the MIKE 11 model.