波浪动力因素变化对沙质岸滩演变的影响

Effects of wave dynamic factors on the evolution of sandy beach

通过波浪水槽实验,对海平面变化造成的波浪动力因素改变引起的沙质岸滩形态响应开展机理性研究。实验采用1∶10单一沙质斜坡概化岸滩,利用3种不同实验水深模拟海平面变化,考虑椭圆余弦波、非规则波、规则波和孤立波4种类型波浪作用。实验对波浪在斜坡上的传播变形、破碎、上爬和回落过程的波高及波浪作用后的岸滩地形进行了测量。实验结果表明,椭圆余弦波、规则波和非规则波作用下,平衡岸滩呈现出滩肩形态,孤立波作用下则呈沙坝形态。海平面上升造成波浪动力增强,沙质岸滩平衡剖面形状基本保持不变向岸平移,槽谷、滩肩、沙坝位置以及岸线蚀退距离,均呈现出良好规律性。

A set of 2Dwave flume experiments on a sandy beach were performed to investigate the morphological response of sandy beach to the wave dynamic factors causing sea-level changes.The initial 1/10 simplex beach slope was exposed to the following different wave actions,i.e.,cnoidal waves,irregular waves,regular waves and solitary waves actions,and three different experimental water depths were used to simulate the sea-level change.This study measured a series of free surface elevations for different waves at the time of wave propagation,wave breaking,uprush and backwash,and cross-shore beach profiles after undergoing wave actions.The results showed that the equilibrium beach profile showed wide high berm topography after undergoing cnoidal waves,irregular waves and regular waves,and yet it became sandbar form topography after undergoing solitary wave action.The equilibrium profile shapes were essentially unchanged but moved shoreward under sea-level rise,and the position of berm,trough,sandbar and the retrograde distance of shoreline show good correlations under the four different wave actions.