Global Distribution and Geomorphology of Fetch-Limited Barrier Islands
Global Distribution and Geomorphology of Fetch-Limited Barrier Islands
复制标题
有限获取障壁岛的全球分布和地貌
DOI：
10.2112/08-1023.1
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
David Bruce Lewis
中科院分区：
文献类型：
--
作者：
O. Pilkey;J. Cooper;David Bruce Lewis
摘要世界上有15,000多个障壁岛，分布在受取水限制的近岸环境中。其中约有一半正在积极演变（侵蚀，增生，迁移），以应对海洋过程，是本研究的主题。剩下的一半由周围的盐沼或红树林保护的不活跃岛屿组成。尽管这些岛屿在全球范围内数量丰富，但之前尚未进行过系统研究，甚至没有被认为是主要的地形类型。超过70%的取水限制障壁岛位于后缘海岸，因为那里的条件有利于形成遮蔽沃茨。其中50%分布在澳大利亚、墨西哥和俄罗斯的沿海地区。我们确定了八种不同类型的提取限制屏障岛的成因和发生模式的基础上。大多数活跃岛屿形成于河口或海湾（澳大利亚斯宾塞湾）、公海屏障岛后面（北卡罗来纳州帕姆利科湾）或公海潮汐入口的洪水潮汐三角洲（新西兰塔波拉浅滩）。其他的则出现在被近海岛屿遮蔽的河流三角洲（土耳其的门德雷斯三角洲）、具有热喀斯特地形的遮蔽海湾（俄罗斯的延西湾）和峡湾的冰川沉积平原（智利的埃斯特万湾）。由于全新世海平面下降，一些南半球岛屿已被困在平均海平面以上，并间歇性地活动（莫桑比克马普托湾）;它们只在春季潮汐和风暴期间被水包围。间歇性岛屿也在高潮汐幅度的条件下形成（澳大利亚国王湾）。受捕捞限制的障壁岛比开阔洋的障壁岛小得多，平均约1公里长，50米宽，最高海拔1至2米。它们以类似于海洋屏障的方式演变，只是过冲几乎总是占主导地位的岛屿建设过程，沙丘的形成则不那么重要。开阔洋障壁岛和受取物限制障壁岛的两个最大区别是：（1）完全依赖风暴的演化;（2）盐沼和红树林植被在控制取物限制障壁岛的形状和位置方面的重要作用。在盐沼和红树林的稳定下，植物控制是造成一些取水有限的屏障岛屿形状不规则的原因，并经常在创造岛屿演变的基础方面发挥作用。这些岛屿目前很少有人定居或开发，但在中纬度地区，它们很可能很快就会受到开发压力。
Abstract There are more than 15,000 barrier islands in fetch-limited nearshore environments around the world. About half that number are actively evolving (eroding, accreting, migrating) in response to oceanographic processes and are the subject of this study. The remaining half consists of inactive islands protected by surrounding salt marsh or mangroves. Despite their global abundance these islands have not been previously systematically studied or even recognized as a major landform type. More than 70% of fetch-limited barrier islands are found on trailing edge coasts because conditions there are favorable for formation of sheltered waters. Fully 50% are found in the coastal zone of Australia, Mexico, and Russia. We identify eight different types of fetch-limited barrier islands based on genesis and mode of occurrence. Most of the active islands form in estuaries or bays (Spencer Gulf Australia), behind open ocean barrier islands (Pamlico Sound, North Carolina), or on flood tidal deltas of open ocean tidal inlets (Tapora Bank, New Zealand). Others occur on river deltas sheltered by offshore islands (Menderes Delta, Turkey), in sheltered bays with thermokarst topography (Yensei Bay, Russia), and on glacial outwash plains in fjords (Golfo Esteban, Chile). Due to a Holocene sea level drop, some southern hemisphere islands have been stranded above mean sea level and are intermittently active (Maputo Bay, Mozambique); they are only surrounded by water during spring tides and storms. Intermittent islands also form under conditions of high tidal amplitude (Kings Bay, Australia). Fetch-limited barrier islands are much smaller than their open ocean counterparts, averaging roughly 1 km long and 50 m wide and 1 to 2 m maximum elevation. They evolve in similar fashion to ocean barriers except that overwash is almost always the dominant island building process and dune formation is much less important. The two biggest distinctions between open-ocean and fetch-limited barrier islands are (1) complete evolutionary dependence on storms and (2) the important role of salt marsh and mangrove vegetation in controlling the shape and location of fetch limited barrier islands. Stabilized by salt marshes and mangroves, vegetative control is responsible for the irregular shape of some fetch-limited barrier islands and often plays a role in creating the foundation upon which the island evolves. Few of these islands are settled or developed at present, but it is likely that in midlatitudes they will soon be under development pressure.