分析汾河流域 1981—2015 年气候、植被和人类取用水的演变特征。结果表明，流域年降水和净辐射分别呈 不显著（p>0.05）增加和减少趋势，叶面积指数显著（p<0.05）增加，人为取用水量波动增加，实测年径流显著（p<0.05） 减少。基于分布式水文模型和因素去趋势方法定量解析降水、净辐射、温度、叶面积指数以及取用水对汾河年径 流减少的贡献。结果表明，取用水的增加是导致汾河径流减少的主要原因，其次为温度、叶面积指数和净辐射的 变化。在上述 4 个因素无趋势情景下，实测年平均径流将分别增加 27.4%、14.4%，13.7% 和 2.1%。降水增加缓解 了年径流的减少。在年降水无趋势的情景下，实测年平均径流将减少 5.3%。上述研究结果可为汾河流域的水资 源管理和规划提供参考。

Under the combined effect of climate change and human activities, there is a sharp decline in the Fenhe River runoff, which aggravates the shortage of water resources in the middle and lower Yellow River. To quantify the contribution of climatic factors, vegetation, and human water use to runoff reduction, the evolution above characteristics is carried out from 1981 to 2015 in the Fenhe River basin. A distributed hydrological model and a factor detrending method were used to quantitatively analyze the contribution of the changes in precipitation, net radiation, temperature, leaf area index, and human water use to the runoff reduction. The results revealed that annual precipitation and net radiation showed an insignificant ( p>0.05) increasing and decreasing trend during the study period. The annual temperature and leaf area index (LAI) showed a significant ( p<0.05) increasing trend and human water use showed a significant ( p<0.05) increasing trend. These factors jointly led to a significant ( p<0.05) decrease in annual runoff in the Fenhe river basin. The increase in human water use was the primary factor leading to the reduction of annual runoff. The observed mean annual runoff increased by 27.4% under the trend-free scenario of human water use. Warming and vegetation greening were the main natural factors causing runoff reduction, while the effect of net radiation was limited. Under the trend-free scenarios of the above three factors, the mean annual observed runoff increased by 14.4%, 13.7%, and 2.1%, respectively. The increase in annual precipitation partly alleviated the decrease in the annual runoff. The observed mean annual runoff decreased by 5.3% under the trend-free scenario of annual precipitation. The findings of this research may provide guidelines for water resources management and plan in the Fenhe River basin.