Journal Article

Monitoring Discharge and Suspended Sediments in the Yangtze River Tidal Reach Using Coastal Acoustic Tomography

Ding, Yuan Feng, Ma, Yun Long, Zhu, Xiao‐Hua, Liu, Zhao‐Jun, Xiao, Cong, Zhu, Ze‐Nan, Zhong, Ji Wen, Zhang, Chuanzheng, Zeng, Rui, Wei, Li Xin

2025

Overview

Conventional methods of measuring water discharge and suspended sediment concentration (e.g., water sampling and moving acoustic Doppler current profiler [ADCP]) present challenges in large tidal rivers due to temporal and spatial constraints. This study introduces a novel approach to monitor water discharge and suspended sediment discharge (SSD) in large tidal rivers. Total water discharge and SSD exhibit notable variability in tidal rivers due to the river–tidal interactions; understanding this variability and its causes is essential for effective tidal river management. From June to November 2023, a field study was conducted at Nanjing (NJ) to continuously monitor water discharge, suspended sediment concentration (SSC), and SSD in the tidal reaches of the Yangtze River using coastal acoustic tomography (CAT). Total water discharge ranged from 8,765 to 43,356 m3/s, with a mean of 27,825 m3/s, while tidal discharge varied between −11,998 and 9,983 m3/s, with a mean of 69 m3/s. SSC ranged from 0.02 to 0.09 kg/m3, and SSD ranged from 110 to 3,823 kg/s. Tidal variations in SSC and SSD were within ±0.04 kg/m3 and −1,252 to 1,410 kg/s, respectively. Over short timescales, tides caused instantaneous fluctuations in velocity, water discharge, and SSD, with tides contributing −40% to instantaneous water discharge and SSD at NJ. Over seasonal timescales, no significant wet/dry variations were observed in water discharge, SSC, or SSD during a few months of 2023. Long‐term CAT application (e.g., decades) is required to reveal trends in tidal river dynamics. Plain Language Summary Due to temporal and spatial limitations, traditional methods for measuring suspended sediment concentration (SSC) and discharge, such as moving acoustic Doppler current profilers (ADCP), fail to directly measure transect variations in water discharge, SSC, and SSD in tidal reaches of the Yangtze River. This study developed a new method using coastal acoustic tomography (CAT). Two CAT systems were utilized to continuously measure water discharge, SSC, and SSD at the Nanjing Tidal Station. The CAT results were highly consistent with traditional methods, showing a correlation coefficient greater than 0.9. This study demonstrates the potential of CAT for continuous, real‐time monitoring of water discharge, SSC, and SSD in large tidal rivers. The results showed that mean water discharge, SSC, and SSD are primarily driven by river flow at Nanjing, while tides induce instantaneous variations in water discharge and sediment transport. Key Points Coastal acoustic tomography enabled water discharge and suspended sediment discharge (SSD) monitoring in Nanjing tidal reach of Yangtze River Total water discharge and SSD at Nanjing varied from 8,765 to 43,356 m3/s and 110–3,823 kg/s from June to November 2023, respectively Tides can directly trigger instantaneous variations in sediment discharge, while average sediment discharge is river‐dominated at Nanjing

• Publisher: John Wiley & Sons, Inc,Wiley
• Subject: Acoustic Doppler Current Profiler / Acoustic tomography / Acoustics / coastal acoustic tomography / Correlation coefficient / Correlation coefficients / Doppler sonar / Measurement methods / Profilers / River flow / River management / Rivers / Sediment / Sediment concentration / Sediment discharge / Sediment transport / sediment yield / Sediments / suspended sediment / suspended sediment concentration / suspended sediment discharge / Suspended sediments / tidal river / Tidal rivers / Tidal waterways / Tides / Tomography / Variability / Variation / Water / Water analysis / Water discharge / Water monitoring / Water sampling / Yangtze River