Artificial reefs are being implemented around the world for their multi-functions including coastal protection and environmental improvement. To better understand the hydrodynamic and morphodynamic roles of an artificial reef (AR) in beach protection, a series of experiments were conducted in a 50 m-long wave flume configured with a 1:10 sloping beach and a model AR (1.8 m long × 0.3 m high) with 0.2 m submergence depth. Five regular and five irregular wave conditions were generated on two types of beach profiles (with/without model AR) to study the cross-shore hydrodynamic and morphological evolution process. The influences of AR on the processes are concluded as follows: (1) AR significantly decreases the incident wave energy, and its dissipation effect differs for higher and lower harmonics under irregular wave climates; (2) AR changes the cross-shore patterns of hydrodynamic factors (significant wave height, wave skewness and asymmetry, and undertow), leading to the movement of shoaling and breaking zones; (3) the beach evolution is characterized by a sandbar and a scarp which respectively sit at a higher and lower location on the profile with AR than natural beach without AR; (4) the cross-shore morphological features indicate that AR can lead to beach state transformation toward reflective state; (5) the scarp retreat process can be described by a model where the scarp location depends linearly on the natural exponential of time with the fitting parameters determined by wave run-up reduced by AR. This study demonstrates cross-shore effects of AR as a beach protection structure that changes wave dynamics in surf and swash zone, reduces offshore sediment transport, and induces different morphological features.

中文翻译：

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人工礁对波浪主导海滩跨岸形态动力学过程影响的实验研究

人工鱼礁因其包括海岸保护和环境改善在内的多种功能而在世界范围内实施。为了更好地了解人工鱼礁 (AR) 在海滩保护中的流体动力学和形态动力学作用，在 50 m 长的波浪水槽中进行了一系列实验，该波浪水槽配置有 1:10 的倾斜海滩和模型 AR（1.8 m 长 × 0.3 m 高），0.2 m 淹没深度。在两种类型的海滩剖面（有/没有模型 AR）上生成五个规则和五个不规则波浪条件，以研究跨岸水动力和形态演化过程。得出AR对过程的影响如下：(1)AR显着降低了入射波能量，在不规则波浪气候下，其耗散效应对高次谐波和低次谐波有所不同；(2) AR 改变了水动力因素（显着波高、波浪偏斜和不对称、逆流）的跨岸格局，导致浅滩和破碎带的运动；(3) 海滩演化的特点是沙洲和陡崖分别位于有增水作用的剖面上比没有增水作用的天然海滩高和低的位置；(4) 跨岸形态特征表明AR可以导致海滩状态向反射状态的转变；(5) 陡坡后退过程可以用一个模型来描述，其中陡坡位置线性依赖于时间的自然指数，拟合参数由 AR 减少的波浪爬高确定。这项研究证明了 AR 作为海滩保护结构的跨海岸效应，可以改变冲浪和冲刷区的波浪动态，