Characterizing Hydrologic Response at Multiple Time Scales for Tarim River Basin Headstreams

The long-term hydrologic response for the headstreams of the Tarim River basin was analyzed on the basis of major hydroclimatic data collected at 10 weather stations and seven gauge stations between 1962 and 2007. A nonparametric trend test at the basin scale for annual data showed an increasing trend of air temperature and precipitation since 1984 for this region. A quantitative assessment revealed that since 1972, local human activity has led to a decrease in the water volume diverted into the main stream of the river basin, a trend that intensified in 1992. A scale-based decomposition method, the empirical mode decomposition, was also applied to the total natural runoff and total runoff time series. The correlation between the intrinsic mode functions (IMF) from the runoff time series demonstrated a strong correlation among the larger-scale IMF modes, which indicated that both runoff series are controlled by the same climate events. Scaling range and intermittent fluctuations of IMF modes and phenomena over the range of scales were found to be less than 12 years and were likely caused by local anthropogenic activities. The results obtained in this study can provide information for planning and managing the limited water resources in the study area.