Climate change implication for Hydropower development in Nepal Himalayan region

Abstract

The effects of Climate change on precipitation pattern and hydrological regime are the most critical to hydropower generation. The trends on changes, though not exactly quantified, are visualized to be heterogeneous over different ecological zones of Nepal. Certain areas especially higher Himalayas of Nepal are becoming increasingly susceptible to hydrological transformations caused by climate change. Changing pattern of temperature is more visible and clear than precipitation. Changes in evaporation rates, annual river discharge, seasonal and temporal offsets of hydrological patterns, extreme precipitation events, and increased glacial melt are the most pertinent climate change effect that has impacted hydroelectric generation. Erosion and transport pattern of sediment is directly influenced by the pattern of changes in precipitation and runoff. Warming affected glaciers not only to contribute more water but also to the development of GLOF hazards. Rivers from Himalaya are enriched by snow and glaciers melt. Snow melt contribution varies monthly with temperature and solar radiation over the ablation part of the snow and glacier areas in the catchment. Assessment river basin indicated that the snow melt contribution could reach up to 40 % in basin upper Kaligandaki and 20% in Kosi basin. The worst scenarios as per the present projection are that future flow characteristics of snow fed rivers could appear to be like that of present pattern of non-snow fed rivers. The methodology of the study was based on research output made available as published literatures, various scientific studies results and information from multiple sources that are focused on climate change vulnerability to water resources, especial focus on hydropower, are synthesized and integrated.