In the present research, we used bias corrected output of regional climate model (RegCM4.3) to generate streamflow for future climate change projections in the Northwestern Upper Indus Basin (NUIB) under RCP4.5 and RCP8.5 scenarios. The average annual runoff was found to be continuously increasing by the end of 21st century. The increase in precipitation as well as the streamflow for summer and winter in the NUIB indicated that RegCM4.3 simulated climate change projections were realistically transferred to HEC-HMS hydrological model. Maximum streamflow peaks, both in frequency and magnitude, were observed in July and August over three streamflow gauges (i.e. Besham, Nowshera and Khairabad) posing possible threats of flood risks during the monsoon season in Pakistan. Significant streamflow changes were projected for winter and spring seasons. The analysis of flow duration curve for three hydrometric stations indicates that the flow occurrence probability could be greater under both scenarios relative to the reference period. The increase in streamflow was projected under high (Q₅) and medium (Q₅₀) flow, which could possibly be related with the increase in monsoon precipitation events in the NUIB. Overall it is to be expected that the NUIB will confront more floods as a result of projected increase in medium and high flow, which demands better policies and management towards the water resources of the NUIB. This study is expected to contribute considerably to climate change impact assessment studies over the NUIB, Pakistan.

在本研究中，我们使用偏向校正的区域气候模型（RegCM4.3）输出在RCP4.5和RCP8.5情景下为西北印度河上游盆地（NUIB）的未来气候变化预测生成流量。据发现，到21世纪末，年均径流量将持续增加。NUIB夏季和冬季降水的增加和流量的增加表明，RegCM4.3模拟的气候变化预测已实际地转移到了HEC-HMS水文模型中。在7月和8月，在三个流量表（即Besham，Nowshera和Khairabad）上观察到了最大的流量峰值，频率和幅度最高，这可能在巴基斯坦的季风季节造成洪水威胁。预计冬季和春季会出现明显的流量变化。对三个水文站的水流持续时间曲线的分析表明，相对于参考周期，两种情况下的水流发生概率都可能更大。预计流量增加将在₅）和中等（Q ₅₀）流量，这可能与NUIB中的季风降水事件增加有关。总体上，由于预计中，高流量的增加，预计NUIB将面临更多的洪水，这需要对NUIB水资源进行更好的政策和管理。预计该研究将为巴基斯坦国家生物多样性研究所的气候变化影响评估研究做出重要贡献。