利用乌云河东风水文站月流量、月降水量和蒸发量资料，通过计算水文和气象要素的变差系数、峰型度和丰枯率及气候倾向率等参数，分析了乌云河径流的主要补给来源及降水和蒸发量等气候因子对径流的影响。研究结果表明：（1）乌云河年径流的变差系数为0.32，其主要由融雪和夏季的降雨来补给，径流年际呈逐渐降低的趋势发展，春、夏、秋、冬四季、汛期及非汛期的流量均呈递减趋势，而且汛期流量减少的最为明显；（2）乌云河的降水量和蒸发量的年际变化也呈递减趋势，蒸发量的减少趋势较为明显，其气候倾向率达到－175.0 mm/10 a。分析认为，降水量的逐渐减少可能是影响该流域流量逐渐降低的原因之一。

Based on the data of monthly flow, monthly precipitation, and monthly evaporation at the Dongfeng Station in the Wuyun River Basin, we analyzed the main water supply source to the runoff of Wuyun River and the effects of precipitation and evaporation on the runoff of Wuyun River through the calculations of variation coefficient, , peak-pattern degree，high and low runoff ratio, and the climate tendency rate of the hydro-meteorological elements. The results showed that（1）the variation coefficient of annual runoff is 0.32 in the Wuyun River, and the runoff is mainly supplied by snowmelt and precipitation in summer. The annual runoff decreases gradually in four seasons, flood season, and non-flood season, and the decreasing of runoff is more significant during the flood season; and (2)the precipitation and evaporation in the Wuyun River decrease annually and the climate tendency rate of evaporation is -175 mm/10 a. The analysis indicated that the gradual reduction of precipitation may be one of the reasons to cause the decreasing of runoff in the Wuyun River Basin.

水沙科学与水利水电工程国家重点实验室开放研究基金资助（sklhse-2013-A-03）