376 / 2024-02-29 23:37:09

Prediction of the evolution of the relationship between rivers and lakes in the middle reaches of the Yangtze River

the middle reaches of the Yangtze River; the Dongting Lake; river-lake relation; mathematical model; river scouring and silting

ABSTRACT: Since the operation of large reservoirs in the upper reaches, the relationship between the rivers and lakes in the middle of the Yangtze River has undergone profound changes, which has changed the hydroponic situation in the middle reaches of the Yangtze River. In order to demonstrate the trend of future changes in the relationship between the rivers and lakes in the middle reaches of the Yangtze River, the 1991-2000 water and sediment series, which considering the sediment interception by upstream reservoirs, was adopted, and a one-dimensional mathematical model was used to predict the trend of erosion and sedimentation evolution in the middle reaches of the Yangtze River over the next 20 years. The results show that: 1) After the impoundment of the three Gorges Reservoir in 2003, the middle reaches of the Yangtze River are generally in a state of erosion, and the cumulative amount of the suspension quality of the Yichang to the Datong Reach is 26.87×10⁸m³ from 2021 to 2040; Except for the Yizhi Reach, which has basically reached a balanced state of erosion and sedimentation, other reach will continue to be in a trend of erosion. 2) The three distributary flood channels in the Dongting Lake area are generally showing a trend of erosion, and that the cumulative erosion amount was 0.899×10⁸m³ from 2021 to 2040; The erosion amount of Songzi River is relatively the largest, while the Ouchi River and Songhu Hongdao are basically equivalent, and the Hudu River is the least. 3) The main lake area of the Dongting Lake is still in the state of sedimentation, but the amount of sedimentation has significantly decreased and the sedimentation rate of sediment has decreased; The section of the four river tails gradually changed from siltation to erosion, resulting in the total amount of accumulation gradually decreased; the accumulated sedimentation in the Dongting Lake area was 1.641×10⁸m³ from 2021 to 2040, with an average annual sedimentation of 821×10⁴m³.