Measurements and Analysis of Water Discharges and Suspended Sediment Fluxes in Changjiang Estuary
Received date: 2005-07-17
Revised date: 2005-10-27
Online published: 2006-01-25
Supported by
National Basic Research Program of China, No. 2002CB412401; National Natural Science Foundation of China, No. 40106009
An RDI WH600 ADCP has been deployed on a moving vessel for the water and suspended sediment fluxes measurements in the Changjiang Estuary. The acoustic signals recorded have a significant relationship with the suspended sediment concentrations (SSCs) obtained by in-situ water sampling during the measurements. Then the acoustic SSC models established were used to convert ADCP acoustic signals into high-resolution SSCs along the cross-sections at Xuliujing and the bar shoal at South Trough in the Changjiang Estuary. The analysis of current velocity profiles shows that the study area is characterized by the rectilinear current at the Xuliujing area. The maximum water and suspended sediment fluxes present during the flood period. However, since the ebb period is much longer than the flood period and the river discharge is huge, the water and suspended sediment fluxes are larger during the ebb than those during the flood. Thus, the net water and suspended sediment transport towards the sea. For example, the net water and suspended sediment are 0.71×109 m3 and 2.5×108 kg during a tidal cycle on November 12, 2003, respectively. Nevertheless, the current is with a rotary pattern at the bar shoal at South Trough of the Changjiang Estuary. The surveyed data also shows that the water and suspended sediment fluxes are larger during the flood than those during the ebb. We also find that a significant relationship exists between the water discharge measured at Datong Station and that at Xuliujing cross-sections from 1998 to 2004. Hence, the derived equations could be used to estimate the daily water discharge through Xuliujing, which can represent the discharge into the sea from the Changjiang River. And the historic water discharge into the sea can be retrieved by using this method. In addition, the annual water discharge into the sea is slightly larger than the annual discharge at Datong Station. However, during the dry period (water discharge < 104 m3/s at Datong Station), the discharge into the sea is smaller than that measured at Datong Station, which may be resulted from the human activities.
WANG Yaping, PAN Shaoming, WANG H.V., GAO Jianhua,YANG Yang, WANG Aijun, LI Zhanhai, WU Zhong . Measurements and Analysis of Water Discharges and Suspended Sediment Fluxes in Changjiang Estuary[J]. Acta Geographica Sinica, 2006 , 61(1) : 35 -46 . DOI: 10.11821/xb200601004
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