A bias-corrected CMIP6-SWAT assessment of Nepal's Gandaki Basin found that under an SSP5-8.5 warm-wet scenario, rainfall increased from 1,961 to 4,068 mm and surface runoff from 556 to 1,838 mm, while snowfall fell from 392 to 231 mm. These are scenario-model outputs, not certain forecasts.
Key findings
- In the severe warm-wet scenario, rainfall and runoff rose sharply, snowfall declined and reported groundwater flow increased from 309 to 600 mm. The pattern suggests a shift from snow storage toward rainfall and faster flow, although groundwater direction may vary by location and scenario.
Why this matters globally
Himalayan basins support large populations and hydropower systems. Multi-site calibration helps dam operation, flood warning, irrigation and dry-season planning account for upstream-downstream heterogeneity rather than a single basin average.
Thai researcher contribution
Five authors are affiliated with the Thailand-based Asian Institute of Technology, collaborating with Nepalese and international partners on a data-scarce mountain basin.
Limitations to consider
Historical fit does not validate future climate. Results depend on climate models, bias correction, emissions pathways, SWAT parameters and sparse snow or groundwater observations; the warm-wet output should not be presented as the single expected future.