Hydropower and Climate Resilience of Nepal Himalaya: A bottom-up Hydrological Approach

We modelled the hydrological response of a central Himalayan country Nepal in HEC-HMS hydrological model, disaggregating the country into three large basins (Eastern, Central and Western) and 94 sub-basins, using daily precipitation and temperature data from 176 and 106 observation stations, respectively. The models were calibrated and validated at 24 stream flow gauging stations over a 20-years period (1991–2010) and simulated for a baseline (1981–2015) and future 35 years. Six future climate scenarios were generated through a bottom-up weather generator using the Autoregressive Moving Average Method (ARMA) method which were analyzed using the hydrological models. We compared the likely impacts of changed climate in future on energy generation of 30 large run-of-river hydropower projects with respect to the Baseline. This is the first study in Nepal which has used the bottom-up method of climate change analysis at the national scale focusing on hydropower. Results indicate regional differences in hydrological responses; the Eastern Basin hydropower projects are expected to face larger variabilities in energy generation compared to the Central and Western Basin projects. However, many projects in the Central and Western basins are likely to meet only 70% of their energy targets in future. Large spatial and temporal heterogeneity in climate can be attributed to the atmospheric interaction with complex topography of the Himalayan region. This research emphasizes the need for a project evaluation framework that incorporates climate resilience into project prioritization. Moreover, this study contributes to multiple aspects by providing comprehensive insights into Nepal’s energy sector through hydroelectricity generation; and advancing assessment methodologies for sustainable energy planning and climate resilience targeted at the Himalayan region in general.