摘要:
海滩养护目前已成为防治海岸侵蚀的主要措施。养滩工程后海滩剖面发生较大的变化,对剖面的变化过程进行研究,可以理解海滩地貌和动力之间的关系,同时也可以对养滩工程进行评价。通过对北戴河西海滩和中海滩两处养护海滩剖面的养护前、养护初、3个月、6个月、9个月和1年后等时间节点进行剖面形态测量,对海滩剖面的变化进行研究。结果发现填沙区内海滩在养滩工程初,滩肩按照设计增宽约30 m,即原岸线平均向海推进约30 m;养滩3个月后填沙岸段侵蚀较大,两个海滩滩肩宽度共缩小约7~14 m;6个月后滩肩宽度相比3个月时再减小4 m,大部分剖面蚀退量开始减小;9个月后和1年后的侵蚀量相对之前更少,有些剖面甚至开始淤积。由于填沙区内侵蚀的物质向两侧运移,使得填沙区外海滩剖面则基本上一直处于淤积状态。1年后滩肩宽度相比养护前宽度增宽约为12~16 m。西海滩和中海滩在1年后填沙保存分别为88.7%和75%,养滩效果良好。
Abstract:
Beach nourishment is widely adopted as a main measure to combat coastal erosion in Europe, the USA, Japan and other developed countries. Usually, beach profiles changes are obvious after the nourishment. Studying the morphological change of beach profiles can help us understand the relationship between the beach morphology and the driving force and assess the consequences of beach nourishment. In this paper, we presented the profiles measured at the western and middle Beidaihe Beaches before, immediately(in a month), 3 months, 6 months, 9 months and 1 year after the beach nourishment. Immediately after the nourishment, the shoreline of the beach moved seawards for about 30m on average, then after 3 months, it retreated back significantly in the nourished area for about 7~14m. The unit erosion rate in most of the profiles, however, decreased gradually after 6 months, the beach berm was eroded by 4m only comparing to that after 3 months. The beach erosion after 9 months and 1 year of the nourishment was much less than before. In some of the profiles there is even siltation around the beach boundary. 1 year later, the beach berm was broadened by about 12~16m comparing to that before nourishment. The ratio of sand preservation in the western and middle beaches reached 88.7% and 75% respectively, showing a great success.
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