珊瑚礁礁坪宽度对波浪传播变形及增水影响的实验研究
作者简介:姚宇(1982—), 男, 湖南省湘潭市人, 副教授, 从事近海水动力学研究。E-mail: yaoyu821101@l163.com
收稿日期: 2018-07-29
要求修回日期: 2018-11-05
网络出版日期: 2019-04-15
基金资助
国家自然科学基金(51679014)
湖南省科技计划(2017RS3035)
河海大学海岸灾害及防护教育部重点实验室开放研究基金(201602)
Laboratory study on the effect of varying reef-flat width on wave transformation and wave-induced setup
Received date: 2018-07-29
Request revised date: 2018-11-05
Online published: 2019-04-15
Supported by
National Natural Science Foundation of China (51679014)
Hunan Science and Technology Plan Program (2017RS3035)
Open Foundation of Key Laboratory of Coastal Disasters and Defense of Ministry of Education (201602)
Copyright
通过在波浪水槽中进行一系列物理模型实验, 研究珊瑚礁礁坪宽度变化对珊瑚礁海岸附近波浪传播变形及礁坪上波浪增水的影响。物理实验采用理想化的珊瑚礁模型, 测试了3种礁坪宽度下的一系列不规则波工况。实验结果分析表明: 波浪沿礁传播过程中, 短波持续衰减; 低频长波波高沿礁逐渐增大, 直到海岸线附近达到最大; 随着礁坪宽度的增加, 海岸线附近的短波波高呈下降趋势, 低频长波波高的变化规律不显著; 礁坪上的波浪增水受礁坪宽度变化的影响不明显; 通过对海岸线附近的波浪进行频谱分析发现, 礁坪上低频长波的运动存在着一阶共振模式, 且共振放大效应强度受礁坪水深、入射波峰周期和礁坪宽度共同影响。
姚宇 , 何天城 , 唐政江 , 蒋昌波 . 珊瑚礁礁坪宽度对波浪传播变形及增水影响的实验研究[J]. 热带海洋学报, 2019 , 38(2) : 13 -19 . DOI: 10.11978/2018079
A series of laboratory experiments were carried out in a wave flume to study the influences of different reef-flat widths on wave transformation over reef coasts as well as wave-induced setup on reef flats. A series of incident irregular wave conditions were tested based on the idealized reef model with three reef-flat widths. Results show that as waves propagate across the reef, the swell height decays all the way, whereas the infragravity wave height increases gradually along the reef and reaches the maximum at the shoreline. Near the shoreline, the swell height decreases with increasing reef-flat width, but the variation of infragravity wave height with the reef-flat width is not obvious. The effect of varying reef-flat width on wave-induced setup over the reef flat is insignificant. The first resonant mode is identified on reef flat for the infragravity waves, and the level of resonant amplification near the shoreline is determined by the combined effect of reef-flat water depth, incident peak wave period and reef-flat width.
Fig. 1 Experimental setup. h0 donates the offshore water depth; hr donates the reef-flat water depth图1 实验布置图 |
Fig. 2 Swell height (HSS), infragravity wave height (HIG) and total wave height (HT), across the reef profile (wave condition HS0=0.08m, Tp=1.5s, hr=0.05m )图2 不同礁坪宽度(${{W}_{\text{r}}}$)下短波波高(HSS)、低频长波波高(HIG)和总波高(HT)的沿礁变化(波况: HS0=0.08m, Tp=1.5s, hr=0.05m) |
Fig. 3 Variations of swell height (HSS) and infragravity wave height (HIG) with reef-flat width (Wr) near the coastline at G8 (HS0=0.08m). Circles denote Tp=1.5s; Squares denote Tp=1.5s; Triangles denote Tp=2.0s; Solid markers denote hr=0.05m; Open markers denote hr=0.1m图3 海岸线附近(G8)短波波高(HSS)和低频长波波高(HIG)随礁坪宽度(Wr)的变化(HS0=0.08m) |
Fig. 4 Variation of wave-induced setup (${{\bar{\eta }}_{\text{ r}}}$) on the reef-flat width with (a) incident significant wave height (HS0) and (b) reef-flat width (Wr). Circles donate Tp=1.0s; Squares donate Tp=1.5s; Triangles donate Tp=2.0s; Black markers donate hr=0.05m; White markers donate hr=0.1m图4 礁坪波浪增水(${{\bar{\eta }}_{\text{ r}}}$)随入射有效波高(a)和礁坪宽度(b)的变化 |
Fig. 5 Variation of wave spectra with different reef-flat widths (Wr) across the reef profile (HS0=0.08m, Tp=1.5s, hr=0.05m). The dashed line denotes the splitting frequency between the swell wave and the infragravity wave frequency bands图5 不同礁坪宽度(Wr)条件下波浪谱的沿礁变化(HS0=0.08m, Tp=1.5s, hr=0.05m) |
Fig. 6 Wave spectra within the infragravity band ($f$= 0 - 0.33 Hz) near the coastline (G8) under different water depths (hr), periods (Tp) and reef-flat widths (Wr). (a) HS0=0.08m, Tp=1.5s, hr=0.05m, Wr=8m; (b) HS0=0.08m, Tp=1.5s, hr=0.1m, Wr=8m; (c) HS0=0.08m, Tp=1.0s, hr=0.05m, Wr=8m; (d) HS0=0.08m, Tp=2.0s, hr=0.05m, Wr=8m; (e) HS0=0.08m, Tp=1.5s, hr=0.05m, Wr=4.8m; (f) HS0=0.08m, Tp=1.5s, hr=0.05m, Wr=11.2m. In each plot, the left vertical dashed line denotes the first-order resonant frequency, and the right vertical dashed line denotes the second-order resonant frequency图6 海岸线附近(G8)低频波浪频谱(f = 0~0.33Hz)随礁坪水深(hr), 波浪周期(Tp)和礁坪宽度(Wr)的变化 |
The authors have declared that no competing interests exist.
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