Berm development on a monsoon‐influenced microtidal beach
Berm development on a monsoon‐influenced microtidal beach
复制标题
受季风影响的微潮海滩上的护堤发展
DOI：
10.1111/j.1365-3091.1986.tb00759.x
复制
发表时间：
1986
期刊：
影响因子：
3.5
通讯作者：
M. Baba
中科院分区：
文献类型：
--
作者：
K. V. Thomas;M. Baba
探讨了微潮高能海滩护堤沿着发育的机理。这样一个海滩与中等大小的沙子和季风波控制的轮廓在Valiathura，印度西南海岸，被选中进行这项研究。波浪很少低于1米，在5月至10月的季风期间经常超过4米。海滩的冲淤模式具有旋回性，滩肩的发育主要是由于季风大风季节后沿岸砂坝向岸迁移并焊接到海滩上所致。在目前的小潮海滩的护堤发展阶段是或多或少类似的模型中潮的情况下，除了以下的中间附加阶段。当波陡大于0.04时，沿岸沙坝因海滩侵蚀而发育，当波陡小于0.04时，沿岸沙坝变平，然后在靠近海岸线处重新形成冲沙坝。这个改造酒吧得到分割和内部酒吧得到焊接到海滩，其次是外部酒吧发展护堤。在沿岸沙坝和护堤发育的向岸迁移过程中，海滩面变为部分反射面，冲浪尺度参数eb在2·5和33之间。近岸是耗散的近岸冲浪缩放参数，es 33。沿岸沙洲的离岸侧是部分反射的，其冲浪尺度参数ebar在2·5和33之间。碎浪正在倾泄。波浪陡度、碎波高度和类型的变化引起的斜浪极限的变化是导致滩面垂直增长的主要原因。垂直生长停止时，滩面达到平衡的粒度波能关系，波陡低于0·02有助于维持这种状态。
The mechanisms of berm development along a microtidal-high energy beach is examined. Such a beach with medium-sized sand and monsoon wave-controlled profile at Valiathura, south-west coast of India, is selected for this study. The waves which very rarely fall below 1 m, often exceed 4 m during the monsoon period of May to October. The erosion-accretion pattern of the beach shows a cyclicity and the berm development is mainly due to the onshore migration and welding of longshore bars on to the beach following the monsoon rough season. The stages of berm development in the present microtidal beach are more or less similar to the model presented by Hine for a mesotidal case, except for the following intermediate additional stages. The longshore bar develops due to the erosion of beach when the wave steepness was above 0·04, gets flattened when it falls below 0·04, and then reforms nearer to the shoreline as a swash bar. This reformed bar gets divided and the inner bar gets welded on to the beach, followed by the outer bar developing the berm. During the onshore migration of the longshore bar and berm development the beach face becomes partially reflective with the surf scaling parameter, eb between 2·5 and 33. The inshore is dissipative with the inshore surf scaling parameter, es≫33. The offshore side of the longshore bar is partially reflective with its surf scaling parameter, ebar between 2·5 and 33. The breakers are spilling or plunging. Vertical growth of the berm is mainly due to the changes in swash-limit caused by the variations in wave steepness, breaker height and type. Vertical growth stops when the beach-face attains equilibrium with the grain size-wave energy relationship, and a wave steepness below 0·02 helps to sustain this state.