It's unequivocal that the global climate is changing, including the rise in atmospheric temperature and variability in amount and pattern of precipitation, and the rate of temperature change in the Himalayan region is higher than the global average. Since precipitation and temperature are the major driving factors of water resources in the Himalayas both upstream and downstream regions, it is important to understand theimpacts of climate change in water resource availability in the future. In this study, we analyzed the historical hydro-climate data and developed a suitable ensemble of the Coordinated Regional Downscaling Experiment (CORDEX) climate models for the Karnali River Basin (KRB) in western Nepal and assessed the future water availability in different climate scenarios using a semi-distributed catchment scale hydrological model the Soil and Water Assessment Tool (SWAT). The climate data analysis shows that the atmospheric temperature is rising throughout the basin but there is high spatial variability in precipitation trend. The historical river discharge data analysis do not show any significant trend, however, there is some inter-annual variability. Future projection shows that the annual precipitation amount will increase compared to the baseline so does the river discharge. However, this increase is not uniform for all seasons. The post-monsoon season having the lowest observed precipitation will get lesser amount of precipitation in the future and the river discharge also follows the same trend. These anomalies play a crucial role in determining the future water availability for agriculture, hydropower, ecosystem functioning and its services availability to the people living in the KRB as well as in the downstream region.

中文翻译：

---

模拟尼泊尔喜马拉雅山卡纳利河流域的气候变化对可用水量的未来影响。

毫无疑问，全球气候正在发生变化，包括大气温度的上升以及降水量和降水模式的变化，喜马拉雅地区的温度变化率高于全球平均水平。由于降水和温度是喜马拉雅上游和下游地区水资源的主要驱动因素，因此了解气候变化对未来水资源可用性的影响非常重要。在这个研究中，我们分析了历史水文气候数据，并为尼泊尔西部的卡纳利河流域（KRB）开发了一个适合的区域协调降尺度实验（CORDEX）气候模型，并使用半分布式方法评估了不同气候情景下的未来可用水量流域尺度水文模型土壤和水评估工具（SWAT）。气候数据分析表明，整个盆地的大气温度都在升高，但降水趋势的空间变化很大。历史河流流量数据分析没有显示任何明显的趋势，但是，存在一些年际变化。未来的预测表明，与基线相比，年降水量将增加，河流流量也将增加。但是，这种增长并非在所有季节都统一。季风后季节观测到的降水量最低，将来将减少降水量，河流流量也遵循相同的趋势。这些异常在确定未来农业，水力发电，生态系统功能的水供应以及其对KRB以及下游地区居民的服务可用性方面起着至关重要的作用。