Three dimensional physical modelling study on wave and current characteristics in coral reef coastal system

Chen Shubin; Chen Songgui; Yao Yu; Chen Hanbao

doi:10.12284/hyxb2021087

Volume 43 Issue 5

May 2021

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Chen Shubin，Chen Songgui，Yao Yu, et al. Three dimensional physical modelling study on wave and current characteristics in coral reef coastal system[J]. Haiyang Xuebao，2021, 43(5)：110–119 doi: 10.12284/hyxb2021087

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Three dimensional physical modelling study on wave and current characteristics in coral reef coastal system

doi: 10.12284/hyxb2021087

Chen Shubin^1
,,
Chen Songgui^{1, 2
,
,},
Yao Yu³,
Chen Hanbao²

1.
Key Laboratory of Coastal Disaster and Protection (Hohai University), Ministry of Education, Nanjing 210098, China
2.
Tianjin Research Institute for Water Transport Engineering, Ministry of Transport of the People’s Republic of China, Tianjin 300456, China
3.
Key Laboratory of Water-Sediment Sciences and Water Disaster Prevention of Hunan Province, Changsha 410114, China.

Received Date: 2020-04-01
Rev Recd Date: 2020-05-13

Available Online: 2021-04-15

Publish Date: 2021-07-06

Abstract

Abstract

Based on the on-site observation of the topography, a generalized three-dimensional physical model of coral reef-lagoon-channel system was established in the wave basin. Wave gauges, velocity meters, and surface velocity measurement system were used to analyze wave and current field characteristics at different locations under regular wave condition. The experimental results indicate that over the reef flat, the wave height gradually decreases by 86.7% cross-shore, and wave-induced setup first increases and then decreases by 65.9% along the reef. The mean current direction is mainly cross-shore, and there is a tendency of increasing first and then decreasing. In the lagoon, the wave height is larger near the channel, where wave-induced setup is the smallest. The maximum wave height is about 2.8 times of the minimum value, and the wave-induced setup is 25.5% lower than on both sides. The mean current is mainly a longshore one that points symmetrically to the rip channel. The velocity increases from the two sides to the rip channel first and then decreases. The wave height in the channel does not change much, and largest wave-induced setup is 47.6% than that on the reef. The mean current flows offshore, and increases first and then decreases. Using the results measured by the wave gauges, the spatial changes of the radiative stress and wave surface pressure gradient which drove the circulation were quantitatively analyzed. The current change on the reefs is the result of the interaction between wave surface pressure gradient and the radiant stress. The driving force of the offshore flow in the rip channel is mainly the radiant stress, while the change of the longshore current in the lagoon is determined by the pressure gradient of the mean water level.
- reef-lagoon-channel,
- wave,
- wave induced current,
- radiation stress,
- wave set up,
- three dimensional physical modelling

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References(21)

References

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