塔里木河流域径流变化特征及其对气候变化的响应

The Hydrological Characteristics of Runoff and Its Response to Climatic Change in Tarim

塔里木河是典型的干旱区内陆河，自身不产流，干流水量主要依靠源区河流的补给，本文以塔里木河流域的源流区（出山口以上区域）为研究对象，基于实测水文气象数据运用Mann-Kendall非参数检验、小波分析法和EOF分析法研究历史水文过程的特征与规律，以及区域气候的时空变化特征，分析气候变化对水循环和径流变化的影响。研究结果表明冰川积雪融水是径流的主要补给来源；EOF分析表明源流区内的气温、降水量和蒸发量呈现增加趋势；受冰川调节和区域气温升高的双重影响，年平均径流量多年保持稳定并在近年来有所增加，小波分析表明1990年后在大于15年的时间尺度上进入丰水期；多变量非参数检验表明径流随气温和蒸发量变化较为敏感，月径流量随着气温升高而呈现指数增加的变化趋势，1991年-2002年源区径流量比1956年-1990年增加了6．5％。由于塔里木河流域特殊的地理位置与流域结构，具有河川径流以冰川积雪融水补给比重大的特征，当气温升高1℃径流量相应增加10％-16％，随着气温升高和冰川消融量的增加，径流量也将进一步地增加。

The Tarim River is the typical continental river in China, which runoff-feeding regions are located on upper mountain reaches. The Tarim River Basin covers the entire southern part of Xinjiang in western China that is characterized by both rich natural resources and fragile environments. This paper makes an insight into the change of streamflow and the impact of climatic variability conditions in regional hydrological cycle in the headwater of the Tarim River Basin. The debate on climate variability and climate change relies highly on the detection of trends （or lack thereof） in instrumental records of hydroclimatic variables such as air temperature, precipitation and streamflow. This paper investigates possible causes of observed trends in streamflow in an environment which is highly variable in terms of atmospheric conditions where the thawing snow and ice play an important role in the natural hydrological regime. The discharge trends of three head streams have a significant increase trend from 1957 to 2002 with the MannKendall test. The annual mean discharges totally are observed increasing from 186.17 × 108m^3 （ 1957 - 1970） to 203.7 × 108m^3 （1991 - 2002）. It has an increase of 6.5percent during 1990s compared with the mean discharge from 1956 to 2002. Complex time-frequency distributions in the streamflow regime are demonstrated especially by Morlet wavelet analysis over the past 40 years. The annual runoff time frequency distribution shows a significantly uprising trend of all of mean discharge series signal since 1990s at the time scale of 15 - 20 years. The purpose is to ascertain the nature of climatic factors that EOF （Empirical Orthogonal Function） is used to compare the dominant temperature, precipitation and evaporation patterns from normally climatic rainfall records over the Tarim＇s headwater basin. It shows that the first principal component was dominated since 1990s for temperature and precipitation, which identifies the significant ascending trend of spatial and temporal pattern characteristics under the condition of the global warming. An exponential correlation is highlighted between surface air temperature and mean river discharge monthly, so the regional runoff increases by 10 - 16percent when surface air temperature rises by 1 ℃. This relationship suggest that the environment in the basin is very vulnerable under the point view of climate change because of their watershed properties that promote runoff feeding by glacier and snow thawing water and owing to their fundamental vulnerability to temperature changes that affect rainfall, snowfall, and glacier and ice thawing.