reducing the contribution of the lakes to foods and reducing the pressure on food-control measures along the main stream. Flow rates at the entrances to the river control the infuence of the lakes on fooding in the main stream and determine whether fooding in the middle and lower reaches of the river is comprised of upstream food water or a combination of lake water and upstream food water. However, the fow rate is not the main determinant of fxed fow-rate food water levels.Sedimentation in Dongting Lake and Poyang Lake can be expressed as follows: