1958年以来莱州湾南部海岸线及水下地形演变

On the change of coastline and underwater terrain of the southern Laizhou Bay since 1958

莱州湾南部自20世纪80年代以来海岸地貌发生了显著变化,研究海岸地貌的演变规律对海岸防护和海岸带资源可持续利用具有重要意义。本文以不同时期测量或成像的海图和遥感影像为数据源,基于RS和GIS技术对海岸线和水下岸坡演变进行定量研究。结果表明:①1958–2021年自然岸线逐渐减少,人工岸线逐渐增加,到2021年人工岸线长度约占总长度的87%,海岸线演化与海岸带建设密切相关;②以1984年为界,1984年前以自然演变为主,1984年后人类活动起主导作用,自然演变下海岸线以向陆蚀退为主,人为干预下以向海推进为主;③水下岸坡冲淤分布极不平衡,总体呈侵蚀–淤积–淤积减缓的趋势。南部河流入海口处在1984年后基本呈侵蚀状态。0 m和2 m等深线有前进有后退,但变化幅度相对较小;5~9 m等深线在堤河以西海域向海前进显著,其冲淤演变复杂;10 m等深线以堤河为界表现出西淤东蚀的状态。河流来沙是导致海岸线和水下岸坡演变的重要物质基础,波浪和潮流是主要的驱动力。人工设施在引起河流输沙减少的同时,也导致海岸线大幅向海推进、入海河口受到侵蚀。东北部莱州浅滩附近受人为影响处于侵蚀、解体状态,未来将会继续受到侵蚀。

The coastal geomorphology of the southern coast of Laizhou Bay,Shandong,has changed greatly since the 1980s.It is of great significance to study the evolution of coastal geomorphology for coastal protection and sustainable utilization of coastal resources.We used the charts and remote sensing images measured or imaged in different periods as data sources,and quantitatively studied the coastline and offshore slope evolution based on remote sensing and GIS technology.The results show that:①from 1958 to 2021,the natural shoreline gradually decreased and the artificial shoreline gradually increased.Until 2021,the length of artificial shoreline accounted for about 87%of the total length.Coastline evolution was closely related to the coastal construction;②taking 1984 as the boundary,natural evolution dominated before 1984,and human activities played a leading role after 1984.Under natural evolution,the coastline was dominated by land erosion.Under human intervention,it was dominated by seaward advance;③the distribution of erosion and deposition on the subaqueous slope was extremely unbalanced,and the overall trend was from erosion,siltation,to slowed-down siltation.The southern river estuary was largely eroded after 1984.The 0 m and 2 m isobaths advanced or and retreated slightly.The 5~9 m isobaths advanced seaward significantly in the west of the Dihe River,and the evolution of erosion-siltation was complicated.The 10 m isobath was bounded by the Dihe River,showing the state of westward siltation and eastward erosion.River sediment is the important material basis for the evolution of coastline and subaqueous slope.Waves and tidal currents are the main driving forces.While causing a decrease in river sediment transport,artificial facilities have also led to a significant advance of the coastline and erosion of estuaries.The northeast Laizhou shoal is in a state of erosion and disintegration due to human influence,and will continue to be eroded in the future.