Remarkable channel adjustments have occurred in the Jingjiang Reach of the Middle Yangtze River, since the operation of the Three Gorges Project. Because of longitudinal variability in channel adjustments, an integrated approach to calculating reach-scale bankfull channel dimensions was used. Calculated reach-scale bankfull variables indicate that: (i) the adjustment in the reach-scale bankfull channel geometry occurred mainly in the component of bankfull depth, owing to the construction of large-scale bank-revetment works; (ii) the reach-scale bankfull dimensions responded to the previous five-year average fluvial erosion intensity during flood seasons at Zhicheng, with higher correlations for the depth and area being obtained; and (iii) the flood discharge capacity of the reach was controlled by both the upstream and downstream boundary conditions, and the reach-scale bankfull discharge was expressed by an empirical function of the average fluvial erosion intensity at Zhicheng, and the difference between the flood-average water levels at Zhicheng (upstream) and Lianhuatang (downstream).