Monitoring of Yangtze River Discharge at Datong Hydrometric Station Using Acoustic Tomography Technology

Ze-Nan Zhu,Qiang Li,Hua Zheng,Arata Kaneko,Lixin Wei,Hua Wang,Zhensheng Zhang,Shuming Li,Xiao-Hua Zhu,Chuanzheng Zhang,Jiwen Zhong,Minmo Chen

doi:10.3389/feart.2021.723123

Abstract

To continuously monitor the discharge of the Yangtze River, two coastal acoustic tomography (CAT) systems with synchronized transmission were deployed at the Datong hydrometric station of the Yangtze River from July 2018 to January 2021. To accurately estimate the discharge of the Yangtze River, the cross-sectional averaged flow velocity and area data were estimated by establishing two empirical relationships: one between the range-averaged flow velocity measured by acoustic Doppler current profiler (ADCP) and the reciprocal travel time difference measured by CAT, and the other between the ADCP-measured cross-sectional area and the water-surface elevation (stage). Compared with the discharges directly measured by ADCP, our estimation had the root mean square error of 946 m3/s, accounting for 2.5% of the mean discharge. The discharges varied from 10,981 to 81,807 m3/s over the 2.5-years observational period, with a mean of 30,708 m3/s. The annual mean discharge was 29,163 and 34,763 m3/s in 2019 and 2020, respectively. Our monitoring successfully covered two complete flood processes, with a peak discharge of 69,744 (July 17, 2019) and 81,807 m3/s (July 13, 2020). Our study provides an innovative method to achieve accuracy and real-time monitoring of river discharges even during extreme flood events.

Highlights

Rivers play an important role in the global hydrological cycle and solid transport, with river discharge serving as a key link between continental fresh water and marine salt water (Chen et al, 1988; Chen et al, 2001; Lu, 2004; Haddeland et al, 2014)
Our study demonstrates the excellent application of CAT to real-time high-accuracy river discharge monitoring, which is of significance to scientific research, social production, and flood relief
The time series of discharge (i.e., QU·A UΔt · AH) were accurately estimated based on the above relationships, and showed an improved correlation with ADCP-measured discharge (R2 0.997 and RMSE 946 m3/s)

Summary

Introduction

Rivers play an important role in the global hydrological cycle and solid transport, with river discharge serving as a key link between continental fresh water and marine salt water (Chen et al, 1988; Chen et al, 2001; Lu, 2004; Haddeland et al, 2014). Discharge Monitoring in Yangtze River the continuous discharge These indirect flow measurement techniques of surface flow velocity are extremely susceptible to environmental factors such as wind and rain (Hauet et al, 2009); they result in an inaccurate estimation of surface flow velocity, which in turn, affects the accuracy of estimation of discharge. Moftakhari et al (2013) and Cai et al (2014) estimated the freshwater discharge into the San Francisco Bay and the Yangtze River Estuary by evaluating the tide-runoff interaction. These theoretical models can estimate discharge, the estimates must be verified through long-term continuous monitoring of river discharges. The fall index method (estimating the discharge using the water level differences between adjacent hydrometric stations) has been widely applied to estimate the discharge of the Yangtze River Basin (Wu et al, 2010; Zhang and Gao, 2014), but it is difficult to accurately estimate the drop in the water level, especially during floods

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