Numerical Study on Effect of Topography, Shape, and Multi-branch on Saltwater Intrusion in a Conceptual Estuary
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- VEERAPAGA Nagendram
- Dept. of Civil and Environmental Eng., Tokyo Metropolitan University
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- AZHIKODAN Gubash
- Dept. of Civil and Environmental Eng., Tokyo Metropolitan University
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- SHINTANI Tetsuya
- Dept. of Civil and Environmental Eng., Tokyo Metropolitan University
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- YOKOYAMA Katsuhide
- Dept. of Civil and Environmental Eng., Tokyo Metropolitan University
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抄録
<p> In order to discuss the variation of saltwater intrusion and mixing types in terms of estuarine bed topography, planform shape, channel cross-section and multi-branch, a total of 25 numerical experiments were carried out with a conceptual estuary using a three-dimensional hydrodynamic simulator. The wavy bottom of the channel had less salinity intrusion length (SIL) compared with the flat bottom (reference case) under the constant tidal range and freshwater discharge. This is because of the decrease in velocity of the gravitational flow due to the bottom drag force as well as the trapping of saltwater in the bottom hollows. The SIL was increased in the case of funnel shaped estuary compared with the straight (constant width) channel. For the channel cross-section, the temporal variation of SIL was highest in the case of the triangular cross-section and the mixing condition was changed from partially mixed to stratified with the change in cross-sectional shape from triangular to parabolic and then to the rectangular cross-section. The results from the multi-branch indicated that the sub-channels with different length would affect the saltwater intrusion and mixing condition in the estuary. It was shown from the present numerical experiments that the saltwater distribution in the estuary was significantly affected by the planform shape, bed topography and channel cross-section.</p>
収録刊行物
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- 土木学会論文集Ｂ２（海岸工学）
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土木学会論文集Ｂ２（海岸工学） 75 (2), I_19-I_24, 2019
公益社団法人 土木学会