Evaluation of Temperature and Precipitation Changes under Climate Change Scenarios in Budhi Gandaki River Basin (BGRB), Nepal

Abstract

Climate change has posed a solemn threat to the hydrological firmness of mountainous river basins, with broad impressions on ecological systems, water resources, and hydropower development. This study evaluates the future effects of climate change over the Budhi Gandaki River Basin (BGRB) in Nepal using a collaboration of CMIP6 General Circulation Models (GCMs) under Shared Socioeconomic Pathways 2-4.5 and 5-8.5. Quantile mapping, as an advanced bias correction technique, was applied to enhance the models' accuracy in reproducing the past climate pattern, thereby improving the robustness of the future projection. Conferring to the verdicts, significant warming with maximum temperature increases by the end of the 21st century can be expected over a range of 1.18 to 5.08°C. Some other key seasonal changes noticed in precipitation regimes include increased seasonality, increased winter rainfall, and variable monsoon activity. The consequences highlight the urgent need to integrate bias-corrected climate projections into regional progress and climate adaptation plans. It calls for community-based adaptation approaches coupled with strong infrastructure and sustainable water management regulations so that the emerging risks could be reduced. Our work delivers essential new knowledge linked to the regional effects of climate change in high-altitude basins, confirming the urgent necessity for prompt, evidence-based decision-making to foster climate resilience and sustainable development in Nepal's Himalayan region.