Spatiotemporal Variations of Hydrologic Extremes and Response to Extreme Precipitation in Xiang River Basin

Trends of streamflow and water level extremes are significant indicators reflecting the risk of floods and droughts. The study on trends of hydrologic extremes can provide references for water resource management and flood risk analysis. Based on Mann-Kendall test, this article detected existing trends in extreme streamflow and water level in the Xiang River basin that are most afflicted by frequent and severe floods. Subsequently, continuous wavelet transform method was employed to identify the consistency of changes in extreme precipitation and streamflow. The results show that no significant trends can be detected in annual discharge extremes in Xiang River basin, but the summer high flows show positive trends in the most area of upper and middle river basin. The results of wavelet transform analysis illustrate that highly similar patterns of signal changes can be seen between extreme precipitation and streamflow in upper and middle section of the basin, while the changes in extreme precipitation for the lower reaches do not always coincide with the extreme streamflow.