珊瑚岸礁破碎带附近波浪演化实验研究

Experimental study of wave transformation around the surf zone over fringing reefs

通过波浪水槽实验对珊瑚岸礁破碎带附近波浪演变规律开展研究,实验采用了概化的岸礁模型,测试了4种礁坪水深、4种礁前斜坡坡度和一系列入射波高的组合工况。对破碎带宽度和破碎带附近波浪的入射、反射、透射以及能量耗散进行了测量分析,透射波的计算考虑了礁坪上高次谐波的影响。结果表明:礁坪水深和入射深水波高的比值(即礁坪相对水深)是影响岸礁破碎带附近波浪演化的关键参数,而礁前斜坡坡度的影响在本文测量的范围内可以忽略不计。破碎带宽度与礁坪上浅水波波长为同一数量级,并与礁坪相对水深成反比;透射系数随礁坪相对水深的增大呈线性增长,而反射系数的变化却无类似规律;岸礁能够削弱超过50%入射波能,礁坪相对水深越小,波浪破碎造成的能量耗散越大。

A series of laboratory experiments are performed in a wave flume to investigate the wave transformation around the surf zone over fringing reefs.Experimental results are reported for four reef-flat submergences,four fore-reef slopes and a variety of regular wave conditions using an idealized fringing reef model.The surfzone width,as well as the wave incidence,reflection,transmission and energy dissipation around the surf zone are measured,and the effects of higher harmonics are considered to evaluate the transmission coefficient on the reef flat.Data analysis shows that the ratio of reef-flat submergence to deep-water wave height,i.e.,the relative reef-flat submergence,is a key factor to control the wave transformation around the surf zone over fringing reefs,however the influence of fore-reef slope is negligible within the test range.The sufzone width is comparable with shallow-water wave length on the reef flat and it increases with decreasing of relative reef-flat submergence.The transmitted coefficient increases almost linearly with increasing relative reef-flat submergence but such trend could not be found for the reflection coefficient.More than 50% of incident wave energy can be damped by the fringing reef,and larger energy dissipation occurs at a lower relative reef-flat submergence.