Assessing variability of historical and projected future precipitation extremes is of high value in managing water resources effectively. The Himalayan environment of Nepal is comprised of both hills and mountains. The hills are the most susceptible to precipitation extremes and related natural hazards, which hinder the socio-economic development of the country. This study investigated the variability of extreme precipitation events over the 22 weather stations distributed across the mid hills of Nepal to identify its driving potential of extreme events. Firstly, trends and spatial distribution of different precipitation indices were computed on annual and seasonal scales for the baseline (historical) period of 1986–2015. We found that the annual maximum precipitation amount (1-day, consecutive 3-day, and 5-day) and heavy precipitation days with daily precipitation exceeding 10, 20, and 50 mm (i.e., R10, R20, and R50 respectively) show dominantly falling trends during the historical period. Noticeably, while analyzing at a seasonal scale, we found that the precipitation amount exhibited a statistically significant decreasing pattern during the monsoon season. This study then assessed possible changes of those indices under future climatic conditions using the latest set of scenarios from ten CMIP6 (Coupled Model Inter-comparison Project phase 6) models dataset for the near future period (2021–2050) under two shared socio-economic pathways (SSP245 and SSP585). The projection showed a wider range of deviation with respect to the baseline, predominantly increasing heavy precipitation. Overall, the increasing pattern of the intensity, duration, and frequency of extreme events indicates the region would possess more risks of natural hazards such as floods, landslides, and soil erosion in the future. Furthermore, most of the climate models showed that consecutive dry days (CDDs) are projected to increase, which could significantly impact agriculture facilities, food security, and water scarcity and ultimately could increase the vulnerability of hill communities. Our findings are expected to help understand the extremities of precipitation variability and have strong policy implications indicating that adaptation measures that can reduce risks make society less vulnerable and more resilient to extremes.

评估历史和预测未来极端降水的可变性对于有效管理水资源具有很高的价值。尼泊尔的喜马拉雅环境由丘陵和山脉组成。丘陵最容易受到极端降水和相关自然灾害的影响，阻碍了该国的社会经济发展。本研究调查了分布在尼泊尔中部山区的 22 个气象站的极端降水事件的变异性，以确定其驱动极端事件的潜力。首先，计算了 1986-2015 年基线（历史）期间的年和季节尺度上不同降水指数的趋势和空间分布。我们发现年最大降水量（1天，连续3天，和 5 天）和日降水量超过 10、20 和 50 毫米（即分别为 R10、R20 和 R50）的强降水日数在历史时期呈下降趋势。值得注意的是，在季节性尺度分析时，我们发现降水量在季风季节表现出统计上显着的减少模式。然后，本研究使用来自 10 个 CMIP6（耦合模型比对项目第 6 阶段）模型数据集的近期情景（2021-2050 年）在两个共享的社会经济条件下评估这些指数在未来气候条件下的可能变化。通路（SSP245 和 SSP585）。预测显示相对于基线的偏差范围更广，主要是强降水增加。总体而言，强度、持续时间、极端事件频发，预示着该地区未来面临更大的洪水、滑坡、水土流失等自然灾害风险。此外，大多数气候模型显示，连续干旱日 (CDD) 预计会增加，这可能会显着影响农业设施、粮食安全和水资源短缺，最终可能会增加山区社区的脆弱性。我们的研究结果预计将有助于了解降水变异的极端情况，并具有很强的政策意义，表明可以降低风险的适应措施可以使社会不那么脆弱，对极端情况更具弹性。大多数气候模型显示，连续干旱日 (CDD) 预计会增加，这可能会显着影响农业设施、粮食安全和水资源短缺，最终可能会增加山区社区的脆弱性。我们的研究结果预计将有助于了解降水变异的极端情况，并具有很强的政策含义，表明可以降低风险的适应措施可以使社会不那么脆弱，对极端情况更具弹性。大多数气候模型显示，连续干旱日 (CDD) 预计会增加，这可能会显着影响农业设施、粮食安全和水资源短缺，最终可能会增加山区社区的脆弱性。我们的研究结果预计将有助于了解降水变异的极端情况，并具有很强的政策含义，表明可以降低风险的适应措施可以使社会不那么脆弱，对极端情况更具弹性。