Due to the impact of climate change and human activities, part of the Yongding River has stopped flowing, and the hydrological environment is damaged. The hydrological condition can be used to assess the ecological environment of the watershed, and analyzing the driving factors affecting the hydrological condition is essential for the environmental restoration of the watershed, but it is particularly challenging on a daily scale. This paper used the Indicators of Hydrologic Alteration and the Range of Variability Approach (IHA-RVA) method to screen out the sensitive indicators in different periods that are representative of each river; determined the hydrological variation periods of the upper Yongding River and the two subbasins, the Yang River and the Sanggan River; and quantitatively identified the contribution of climate change and different human activities (water withdrawals and reservoir storage) to the basin's runoff by constructing a daily-scale model named the Water and Energy Transfer between Soil, Plants, and Atmosphere (WetSpa) model. The results showed that the upper Yongding River, the Yang River, and the Sanggan River had a high degree of variation (87.2%), a low degree of variation (20%), and a moderate degree of variation (37.5%) in 1975-1988, 1980-1986, and 1978-1993, respectively. Human activities were the main driving factors, but their contributions varied across different basins. The Yang River is mostly affected by water withdrawals, with a contribution rate of 125.90%. The Sanggan River was affected mostly by reservoir storage, with a contribution rate of 153.47%. The upper Yongding River was affected mostly by climate change. A stricter management system can reduce the impact of human activities on runoff changes and provide a guarantee for the restoration of the ecological environment of the upper Yongding River.

柴达木盆地北部是柴达木循环经济试验区“一区四园”中三个园区的分布区，水资源匮乏，近20年气候变化又使径流发生了显著改变，对水资源评价、河流生态和非地带性植被产生一定影响。为了全方位评价区域径流特征，本文采用WEP 模型对盆地北部6条河流进行长系列径流模拟，并采用实测与模拟结合的数据，结合PCA法筛选出的8个代表性IHA指标，从产汇流时空规律与环境特征流量不同角度进行分析，结果表明：（1）2001年后，山区径流深增加8%～28%，平原区不产流面积缩小58%；（2）1981到2020年径流系列于本世纪初发生突变，突变后径流量均值增幅8%～25%，近10年的增加分两种情况：有冰川补给的河流增加14%～41%，无冰川补给的河流增加26%～28%；考虑径流系列的不一致性，采用短周期和典型周期系列分别评价冰川融雪型和降水补给型河流的多年平均径流量，计算盆地北部区地表水资源总量为10.52亿m3；（3）小洪水因刺激鱼类产卵成为最典型的环境特征流量，研究发现小洪水次数与历时均增加，洪峰流量增加13%～37%。