过去几十年，全球大部分河流径流在气候变化与人类活动共同作用下发生显著变化，窟野河与无定河位于陕北榆林地区，独特的自然地理条件使得研究区生态环境脆弱，对水资源的依赖性强，并且煤炭开采等人类活动的干扰更是加剧了水资源的短缺。本文基于研究区水文气象数据，以及水保面积、煤炭开采量等资料全面分析了两条河流径流基本特征，径流序列的演变特征，以及定量计算了气候因素与人类活动分别对河流径流变化的影响程度。主要成果如下：

（1）窟野河径流年内分配极其不均匀，径流主要集中于7~9月，径流不均匀系数C_v多年平均值为0.83，完全调配系数C_r为0.33；无定河分别为0.35与0.14，无定河径流年内分配相对窟野河表现均匀，随着河道径流的减少，两条河流径流年内分配趋于均匀。从20世纪50年代开始，径流量相对多年平均总体呈现丰水-平水-枯水的变化趋势。

（2）窟野河1958~2020年径流量呈显著下降趋势，未来河道径流量总体将继续呈下降趋势；研究时段的突变点为1979、1996年，则可分为三个径流序列，即基准期：1958~1979年，人类活动影响期：1980~1996、1997~2020年；研究时段内主要存在4个主周期，分别为4a、9a、15a、29a。无定河1958~2020年径流量同样呈显著下降趋势，未来河道径流量依然将呈下降趋势；研究时段的突变点为1971、1988年，依次分为三个径流序列，基准期：1958~1971年、人类活动影响期：1972~1988、1989~2020年；研究时段内主要存在5a、16a、32 a三个主周期。两条河流的径流与降水均呈正相关，与年平均气温均呈负相关。径流与降水、气温在某些时间段均存在时间尺度不等的显著共振周期，例如1964~1972在高能量区窟野河径流量与流域降水量存在2~4a的显著共振周期，1988~1998年在高能量区无定河径流与气温存在2~5a的显著共振周期。

（3）利用逐步回归模型得到两条河流各个时期径流显著影响因素及相应减水量，其中1960~2015年窟野河径流显著影响因素为降水、气温、水保面积与煤炭开采量。基于基准期（1960~1979年）人类活动影响期1980~1996、1997~2015年煤炭开采造成径流减水量分别是115.2×10⁴m³、7821.2×10⁴m³。无定河1960~2015年窟野河径流显著影响因素为降水、气温、水保面积，基于基准期（1960~1971年）人类活动影响期1972~1988、1989~2015年水保措施造成的径流减水量分别是23644.9×10⁴m³、46599.1×10⁴m³。

In the past few decades, most of the global river runoff has been significantly altered by climate change and human activities. The Kuye and Wuding rivers are located in the Yulin region of northern Shaanxi, where the unique natural geographical conditions make the study area ecologically fragile and highly dependent on water resources. This paper presents a comprehensive analysis of the basic characteristics of runoff from the two rivers based on hydro-meteorological data, as well as information on water conservation areas and coal mining, the evolution of runoff sequences, and the quantitative calculation of the degree of influence of climatic factors and human activities on the changes in river runoff. The main results are as follows.

(1) The intra-annual distribution of runoff in the Kuye River is extremely uneven, with runoff mainly concentrated from July to September, with a multi-year average runoff unevenness coefficient Cv of 0.83 and a complete deployment coefficient Cr of 0.33; the Wuding River is 0.35 and 0.14 respectively, with the Wuding River showing a more even intra-annual distribution of runoff compared to the Kuye River, and with the reduction of runoff in the river, the intra-annual distribution of runoff in the two rivers tends to be more even. From the 1950s onwards, the overall trend of runoff volume relative to the multi-year average is abundant - flat - dry.

(2) The runoff of the Kuye River from 1958 to 2020 shows a significant decreasing trend, and the future runoff of the river will continue to show a decreasing trend in general; the abrupt change points of the study period are 1979 and 1996, then it can be divided into three runoff sequences, i.e. the base period: 1958 to 1979, the period influenced by human activities: 1980 to 1996, 1997 to 2020; there are mainly four main cycles in the study period, 4a, 9a, 15a and 29a respectively.The runoff of the Wuding River also showed a significant decline from 1958 to 2020, and will continue to show a declining trend in the future; the abrupt change point of the study period is 1971 and 1988, which can be divided into three runoff sequences in turn, namely, the base period: 1958 to 1971, the anthropogenic influence period: 1972 to 1988, 1989 to 2020; the study period is divided into three runoff sequences, namely, the base period: 1958 to 1971, the anthropogenic influence period: 1972 to 1988, and the anthropogenic influence period: 1989 to 2020. The main periods of the study are 5a, 16a and 32a. The runoff of both rivers is positively correlated with precipitation and negatively correlated with mean annual temperature. For example, from 1964 to 1972, there were significant resonance cycles of 2-4a between runoff and precipitation in the high energy area of the Cuyuno River, and from 1988 to 1998, there were significant resonance cycles of 2-5a between runoff and temperature in the high energy area of the Wuding River.

(3) A stepwise regression model was used to obtain the significant factors influencing the runoff and the corresponding water reduction in each period of the two rivers, in which the significant factors influencing the runoff of the Kuye River from 1960 to 2015 were precipitation, temperature, the area of soil and water conservation measures and the amount of coal mining. Based on the baseline period (1960-1979), the water loss due to coal mining in 1980-1996 and 1997-2015 was 115.2×10⁴m³, and 7821.2×10⁴m³ respectively. The significant influencing factors of runoff from 1960 to 2015 in the Wuding River are precipitation, temperature and the area of soil and water conservation measures. Based on the base period (1960 to 1971) the runoff reduction caused by water conservation measures in the anthropogenic influence periods 1972 to 1988 and 1989 to 2015 are 23644.9×10⁴m³ and 46599.1×10⁴m³ respectively.