High and Low Water and Sediment Flows in the Five Tributaries of Poyang Lake

Abstract

【Objective】 Located in Jiangxi province, Poyang Lake is the largest freshwater lake in China. It has five tributaries, and this paper analyzes the change in water and sediment flows at their confluences with the lake. 【Method】 The study was based on runoffs and sediments measured from hydrological stations in the five tributaries. Temporal evolutions of water flow and sediment transport were analyzed using the sliding correlation coefficient method, double cumulative curve method, and copula function. We also calculated the probability of occurrence of flooding and droughts during different periods in the basin. 【Result】 The analysis showed an overall increase in total runoff in all five tributaries, with the most significant increase observed in the Xiu River. In contrast, the total sediment flow exhibited a significant decrease, except the Rao River which showed a significant increase in sediment flow. Abrupt changes in water-sediment relationship were identified for all tributaries, except the Fuhe River. Following the abrupt changes, the Xinjiang River experienced a maximum increase in runoff (15.9%), whereas Ganjiang River had a maximum decrease (67.3%). Compared with the 1956—1971 period, the runoff in the Raohe River in the 2004—2018 period increased by 100.3%. Asynchrony between high and low levels of water and sediments in the five tributaries was less probable compared to synchronous high and low levels, with the highest probability observed for the same level of high and low levels. 【Conclusion】 Extreme precipitation, soil and water conservation projects, reservoir construction, and sand mining in the tributaries and lake are the factors that have significantly influenced water and sediment changes in the basin.

Keywords

• copula function
• water-sediment relationship
• poyang lake basin
• climate change
• human activities