A rougher river bed increases a river’s hydraulic resistance, and raises water levels. Afer water was stored in the TGR, the river bed downstream became rougher. Te median grain size (D50) of the surface of the river bed between Yichang and Zhicheng increased by a factor of 48, i.e., from 0.638mm in December 2003 to 30.4 mm in October 2010. Between Zhicheng and Dabujie, the D50 value increased by a factor of 20. Te roughness increased by 91%, 65%, 3%, and 2% in reaches below the TGD from Yichang to Zhicheng (distance to Yichang is approximately 61 km), from Zhicheng to Dabujie (61 km to 116.4 km), in the upper Jingjiang reach (116.4 km to 319 km), and from Chenglingji to Hukou (319 km), respectively (Table 5).