Trend and abrupt analysis of Dongting Lake water level and its driving forces using Mann-Kendall approach

Abstract

In order to quantitatively describe the evolution trend of Dongting Lake water level and its driving forces, the Mann-Kendall approach is used to determine the lake water level and its driving forces, including the discharge of the Yangtze River at Yichang hydrological station, three outlets, and four rivers. The results show that the annual runoff and the runoff from September to October of the Yangtze River, the annual runoff of the three outlets have a significant downward trend, especially after the impoundment of the large reservoirs on the middle and upper reaches of Yangtze River. The Yangtze River discharge has a sudden change during the impoundment period, while the annual runoff and the runoff from September to October of the four rivers showed an insignificant decrease trend. The lake water level at Chenglingji decreased during the impoundment period of the large reservoirs slowed down, especially in September and October, so we can see that the reservoir impoundment is an important factor that decreasing the water level of Dongting Lake.