Measuring discharge in a river with tidal bores by use of the coastal acoustic tomography system

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• 作者：Xiao-Hua Zhu^a ; ^c ; ^{xhzhu@sio.org.cn} ; Chuanzheng Zhang^a ; ^b ; Qingsong Wu^a ; Arata Kaneko^b ; Xiaopeng Fan^a ; Bo Li^a
• 关键词：coastal acoustic tomography ; reciprocal sound transmission ; current measurement ; river discharge ; tidal bore ; Qiantang River
• 刊名：Estuarine ; Coastal and Shelf Science
• 出版年：2012
• 期刊代码：79_02727714
• 类别：env
• 出版时间：1 June, 2012
• 卷：104-105
• 期：Complete
• 页码：54-65
• 文件大小：3124 K

摘要

Eleven repeat reciprocal sound transmission experiments for current measurements were successful carried out from April 2009 to May 2010 in the Qiantang River, China. Ubiquitous are tidal bore intrusions that occur during spring tides in Hangzhou Bay. The experimental site is about 90聽km away from the mouth of Hangzhou Bay. The coastal acoustic tomography (CAT) system consisted of two acoustic transceiver units, one on each side of the river, separated by 3050聽m. During the sound transmission experiments, 42 shipboard acoustic Doppler profiler (ADP) surveys were also performed along the sound transmission line to obtain validation data for reciprocal sound transmission data. The average current along the vertical section, determined from the travel time difference between the reciprocal data, was in excellent agreement with the ADP results, with a root-mean-square difference of 0.04聽m聽s^鈭?. The sudden variations in river discharge caused by the passage of tidal bores were captured well by the CAT. The river discharge (Q_CAT) measured by CAT had a mean value of 2170聽m³聽s^鈭? but varied between聽鈭?097聽m³聽s^鈭? and 7985聽m³聽s^鈭? during the bore events. For the periods with no tidal bores, the water level data were well correlated with the steady river discharges estimated from the CAT data. By using the empirical relationship between these two variables, the annual river discharge (Q_WL) was predicted in the range from 914聽m³聽s^鈭? to 11,982聽m³聽s^鈭?, with a mean of 2737聽m³聽s^鈭?. A comprehensive discussion of the potential sources of error is presented. The resultant Q_WL error (621聽m³聽s^鈭?) is small compared with the range of Q_WL (11,068聽m³聽s^鈭?), implying that the proposed method for estimating river discharge is acceptable.

The present study provides an efficient way for the long-term monitoring of river discharge in large tidal rivers with heavy shipping traffic, such as the Qiantang River.