Stable isotope characteristics in the Poyang Lake region at Jiujiang section of the Yangtze River in different seasons

Abstract

In order to find out the relationship between the Poyang lake and the Yangtze River and other inflowing rivers, and to objectively discuss the influence of the Three Gorges Reservoir's operation on the lake, samples of river water and lake water in the Poyang Lake region at Jiujiang section of the Yangtze River were taken and analyzed for stable isotopic composition. The isotopic composition of rivers and lakes shows a great temporal and spatial variation, which can be used to reveal the relationship between the lake and rivers. The water-supply dispatch effectively reduces the water loss of the lake in spring. In April, the lake greatly recharges the Yangtze River because of the considerable flow volume of inflowing rivers which have just entered rainy season. During the flood storage dispatching period, the high water level of the Yangtze River restrains the discharge of lake water. The lower water level of the Yangtze River caused by the impoundment dispatch greatly accelerates the water discharge of the Poyang Lake during its dry season. Thus, the water regime of the Poyang Lake basin should be taken into consideration during the dispatches of the Three Gorges Reservoir, alleviating possible floods in wet season and droughts in dry season.