Hydrological Response of Runoff to Climate Variation in Kaidu Catchment
开都河流域径流对气候变化的响应研究

With recent comprehensive investigation of TaLimu river, the response of runoff to climate variation of KaiDu river, an important source of TaLimu river, has been a research focus for many scientists. Because a few human activities happened in KaiDu catchment, the variation of runoff is mainly caused by climate change, especially in yearly and seasonal temporal scale. KaiDu catchment is located in the middle of TianShan mountain in XinJiang municipality and has only one meteorological station and one hydrological station within the range of 19012km2. On the large spatial-temporal scale or in the case of data absence, researchers often divide runoff, precipitation and temperature series per ten years into several periods, then acquire the rule of runoff response to climate though comparing the changes of natural elements between difference periods. Obviously, it is impossible for natural elements to take substaintial changes every ten years, it is reasonable to partition the periods of series according to the varition feature of natural elements. In this paper, Mann-Kendall test and Mann-Whitney test is applied to detection the monotonic trends and step trends of yearly and seasonal runoff, precipitation and temperature series from 1958 to 2000 and take the changes point of trends feature as the boundary of periods.The analysis result show that spring runoff is stable in past 45a, other seasonal runoff and yearly runoff are much smaller during 1974 and 1986 than other periods and show significant monotonic increasing trends after 1987. Yearly average temperature during 1975 and 1988 is lower than other periods and average temperature in summer take step increase after 1977. Precipitation show great spatial differences: upstream area has more precipitation than middle-stream area, yearly precipitation decreased after 1973 and aestival precipitation during 1977 and 1988 is fewer than other periods in upstream area, both yearly and aestival precipitation of middle-stream area increased after 1987. By comparing the variation of runoff, precipitation and temperature on the base of runoff periods partition, it is found that climate variation in summer is key reason for runoff change in summer, autumn and winter, precipitation directly influences the runoff but temperature does it through glacier wastage, precipitation has more weight than temperature in influencing runoff change. The reduction of glacier wastage during 1974 and 1986 make the decrease percentage of runoff greater than precipitation, and the augment of glacier wastage during 1986 and 2000 make the increase percentage of runoff greater than precipitation.