中文摘要：

根据洮河干流4个水文站1956-2009年的逐月径流量资料,从不均匀性和集中程度等方面分析了径流量年内分配的变化特征,并采用Mann-Kendall非参数检验方法分析了流域月、年径流量变化的趋势性.结果表明：洮河干流径流量在枯水季节和丰水季节相差较大,年内分配极不均匀.从时间上来看,1980年以后各水文站径流量的不均匀性和集中程度有所缓解,径流量的集中期有提前的趋势.从空间上来看,洮河流域下游比上游具有更高的不均匀性和集中度,说明越向下游径流量年内分配越不均匀.另外,不均匀性和集中度的相对变化幅度整体有升高趋势.1980年以后洮河干流各月径流量普遍减小,汛期减少尤为明显,且上游枯水期减少趋势大于下游,下游汛期减少趋势大于上游,春、夏季减少趋势大于秋、冬季.洮河干流径流量的年际变化较为剧烈,1980年以后洮河干流年径流量明显减小,且下游减少趋势大于上游.其中,下巴沟、岷县、李家村、红旗站年径流量分别以每年0.14×10^8,0.28×10^8,0.35×10^8,0.37×10^8m^3的速率递减,递减量分别占多年平均径流量的0.91%,0.84%,0.88%,0.81%.

英文摘要：

Based on the observed runoff data of the past 54 years（1956-2009） about the main stream of Taohe River, an analysis was made of the uneven coefficient of seasonal distribution, concentration rate, concentration period and the variation ranges of the runoff by using mathematics statistics. Meanwhile, the Mann-Kendall test method was employed to detect the variation trends of monthly and annual runoff and the results indicated that the annual variability of the runoff was intense, and the intra-annual distribution was extremely uneven. Since 1980, the runoff＇s concentration rate had been lowered and the concentration rate delayed. The downstream area presented a more uneven coefficient and a higher concentration rate than the upstream area. Moreover, the uneven coefficient and the concentration rate showed an increasing trend. The monthly runoff had decreased especially in the flood season after 1980, and the downstream area decreased more than the upstream area, while there had been a contrary trend in the dry season. However, the decreasing trend in spring and summer was more obvious than in autumn and winter. A significant decreasing trend had been found in the annual runoff in Taohe River during the past 50 years at all the observed stations and the downstream area showed a more significant trend than the upstream area. The decrement of the annual runoff is 0.14, 0.28, 0.35, 0.37 hundred million cubic meters, which is 0.91%, 0.84%, 0.88% and 0.81% of the whole year, respectively.