Assessment of the large-scale pattern of precipitation in the Yangtze River basin and its possible impact on streamflow

In recent years, the Yangtze River basin is in a prolonged drought and the ongoing drought in the upper and middle reaches has placed immense pressure on the water resource of upper and mid-lower reaches (see Fig.1). Meanwhile, the Three Gorges Dam (TGD) was raised from 66m to 175m (above sea level) which lead to the situation of water resource becoming more complicated. Therefore, the continuous drought and the TGD have arisen many debates and concerns. Although there are many works about the climate change of Yangtze River and its possible relation to the streamflow, however, more attention has been focused on the floods in the river basin. Only a few studies has been conducted on the subject of streamflow responses to the extremely drought event. Based on the CRU and observed streamflow and precipitation data over 100 years, we analyzed the long-term changes of precipitation pattern in the Yangtze River basin and its impact on steamflow. The patters of precipitation in the upper and mid-lower Yangtze are different and the major differences are as fellows. 1) the maximum monthly precipitation of the lower reaches is detected in June, while that occurs in July in the upper reaches; 2) the precipitation anomalies of the upper and mid-lower reaches always show opposite distribution. But if the precipitation anomalies both in the upper and mid-lower reaches appear similar patterns (both in drought/flood conditions) at the same time, the droughts/floods might make more greatly destroy. Currently continuous drought in the Yangtze River is under the latter condition. Thus, the purpose of this study was focus on the changes of precipitation pattern and its possible impact on the streamflow in the Yangtze River basin. The result will be helpful in improving water resource management in the Yangtze River basin.