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Presentation on climate change impacts on the Kali Gandaki River basin

by Ajay Bajracharya, HI-AWARE Consultant

The critical nature of water resources in the HKH, is a crucial aspect of communities dependent on fresh water. The Himalayan region of Nepal is one of the most fresh water dominant regions for these resources. However, it remains the most vulnerable and affected, due to larger climate change impacts on water resources and the hydrological regime in the region.

A paper focusing on these interlinked issues, has been written by a team of three HI-AWARE researchers- Ajay Ratna Bajracharya, Sagar Ratna Bajracharya, Arun Bhakta Shrestha. The paper titled “Climate change impact assessment on hydrological regime of Kali Gandaki basin in Nepal using RCP scenarios” was presented at the 8th Nepal Geological Congress: “Geoscience in National Development and Disaster Management” held from November 27-29, 2016 in Kathmandu, Nepal.

The presentation focused on the findings of the impact of climate change on the hydrological regime and water balance components of the Kali Gandaki basin in Nepal. The Soil and Water Assessment Tool (SWAT) was used for future projections of the hydrological regime of the Kali Gandaki basin. This was done by running the model with an ensemble of downscaled CMIP5 General Circulation Model outputs. Both the temperature and precipitation of Kali Gandaki basin is projected to increase affecting the water balance components and hydrology of the basin significantly. Rise in average annual temperature by more than 4 °C, and increase in average annual precipitation by more than 25% during the late century under RCP 8.5 scenario is expected to increase the discharge and water yield by more than 50% at the outlet of the basin. Snowmelt contribution is expected to be largely affected by climate change as it is projected to increase as much as 80% during 2090s.

The research also concludes that the water balance components such as snowmelt, evapotranspiration and water yield at higher elevations of upper and middle sub-basins of Kali Gandaki basin are mostly affected due to rise in temperature and increase in precipitation.

The output from this research could be very beneficial in analyzing the effect of climate change on water availability and demand of Kali Gandaki basin. Several hydropower projects under operation and prospective hydropower plants could also benefit from this research. A copy of the presentation can be accessed at the HI-AWARE slideshare account, here.