The Influence of Runoff and Tide on the Salt-Fresh Water Mixing in Estuaries: A Flume Experiment
The salt-fresh water mixing is an important aspect of estuarine dynamic process and the basic research content of estuarine and coastal dynamics. Under the influence of natural factors and human activities, the salt-fresh water mixing state will change with the estuarine conditions. These changes will affect the flow structure, estuarine ecology and sediment movement. The research methods of salt-fresh water mixing in estuaries at home and abroad are mainly field data analysis and mathematical model simulation, while few means of physical model are popularized and employed, due to the high cost of instruments and the difficulty of saltwater recycling and discharge. A long flume (167.8m in length) was employed in the flume test in this study. Through the experimental simulation of tidal reciprocating current and salt-fresh water mixing, the problems of flow velocity control and saltwater regulation were solved. Based on the dynamic conditions of tide and runoff, the spatial and temporal distribution characteristics of velocity and salinity in the salt-fresh water mixing area were quantitatively analyzed by means of characteristic parameters in the dynamic-state. The mechanism of velocity structure and salinity distribution changing with tidal range and runoff discharge was discussed. The velocity and salinity data obtained from the flume test can be used in the basic research of the physical mechanism of salt-fresh water mixing in estuaries. The research results will provide theoretical and experimental basis for solving the problem of saltwater intrusion in estuaries.
KeywordsEstuary Salt-fresh Water Mixing Stratification Runoff Tide Flume test
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This research was funded by the National Key R&D Program of China (No. 2017YFC0405400) and the Special Funds for Basic Scientific Research Operating Expenses of Central Public Welfare Research Institutes (No. Y218010). Thanks to Nanjing Hydraulic Research Institute for support and assistance in the research.
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