Relationship between Waterway Depth and Low-Flow Water Levels in Reaches below the Three Gorges Dam

Abstract

This study analyzes low-flow water levels and expansion of waterway depths in the Yangtze River. It focuses on waterways in the middle and lower reaches of the Yangtze River, known as the Golden Waterway, which are key components of the Yangtze River Economic Zone. Data from 2003 to 2016 indicate that long-distance sedimentation and scour occurs in the downstream channel of the Three Gorges Dam (TGD). High scouring leads to increased waterway depths and greatly reduces the low-flow water level, causing a corresponding decrease in the lowest navigable water level despite increases in both minimum discharge and water level. Waterway depths and widths have increased under the combined actions of river scour and waterway engineering projects, achieving the goals set for 2020, 5 years in advance. Moreover, this study found that the dimensions of the waterways downstream of the dam can be further increased. These findings could be a useful reference for assessing the impacts of reservoir impoundment on downstream water levels and depth, and could assist water resource managers with decision-making processes.