Mathematical model calculations40 s

Mathematical model calculations40 show the following: in the pebble and gravel Yichang–Dabujie reach of the river, afer coarsening of the river bed, the water levels corresponding to Yichang fow rates of 5,000 m3/s, 10,000 m3/s, 23,000 m3/s, and 35,000 m3/s increased by an average of 1.57m, 2.04m, 2.7m, and 3.3m, respectively. Tese values are higher than the actual drop in the water level due to the increased channel depth corresponding to each fow rate increase. Tis explains how coarsening of the river bed efectively mitigated low water-level drops in this pebble and gravel section of the river. In the sandy reaches downstream from Dabujie, the average increases in the water level corresponding to Yichang fow rates of 5,000 m3/s, 10,000 m3/s, 23,000 m3/s, and 35,000 m3/s were 0.13m, 0.11m, 0.16m, and 0.16m, respectively. Tese increases were limited relative to the efects of undercutting.