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浙江苍南近岸海域海床冲淤过程研究
胡高建,戴志军,周晓妍,李为华
0
(华东师范大学河口海岸学国家重点实验室,上海 200241)
摘要:
近岸海床冲淤变化直接反映海区地貌稳定状态,由此影响海区物质迁移及水运资源可持续利用。基于此,本研究通过选择苍南海域不同时期的海图资料,基于ArcGIS平台探讨该海域多尺度海床冲淤过程,为研究区海岸港工建筑规划与评估提供理论指导。主要研究结果包括:苍南海域海床冲淤变化大致分为四个阶段,即1931—1970年大幅淤积,海床净淤积量达到169.47×106m3,淤积强度为5.18 cm/a;1971—2005年海床淤积幅度减弱,海床净淤积量为12.24×106m3,淤积强度为0.41 cm/a;2006—2009年海床由淤转冲,海床净冲刷量为14.70×106m3,冲刷强度为3.60 cm/a;2010—2017年海床持续冲刷,海床净冲刷量为10.17×106m3,冲刷强度为1.33 cm/a。除1931—1970年10 m等深线向海大幅扩张以及1971—2005年10 m等深线有部分向海扩张外,1971—2017年5 m与10 m等深线普遍向陆后退。2006—2017年,位于北关港内的2 m等深线也向陆后退。冲淤结果显示,苍南海域海床未来可能呈现弱侵蚀态势。其中,风暴潮频发导致海床经常性失稳加之长江入海泥沙的减少导致该区域泥沙补给不足,二者共同作用可能是该区域海床由淤积逐渐转为侵蚀的主导因素。
关键词:  海洋地质学  海床冲淤  长江来沙  泥沙输运  苍南海域
DOI:10.3969/J.ISSN.2095-4972.2021.04.016
基金项目:国家重点研发计划政府间国际科技创新合作重点专项资助项目(2018YFE0109900)
Process of seabed erosion and accretion on Cangnan nearshore area, Zhejiang Province
HU Gaojian,DAI Zhijun,ZHOU Xiaoyan,LI Weihua
(State Key Laboratory of Estuary and Coastal Research, East China Normal University, Shanghai 200241, China)
Abstract:
Variations of the nearshore seabed erosion and accretion directly reflect the stability of the geomorpholo gical status of the sea area, which will furtherly affect the sediment migration and the sustainable utilization of waterway resources. In this study, Cangnan sea charts in different periods are selected to diagnose the process of multiscale seabed erosion and accretion in the nearshore zone by ArcGIS platform. The study will provide theoretical guidance for the planning and evaluation of harbor construction along the coast. The results show that the process of seabed erosion and accretion can be divided into four stages. A significant erosion from 1931 to 1970 is that the net deposition over seabed was 169.47×106m3 and the average annual deposition thickness was 5.18 cm. The net deposition over seabed from 1971 to 2005 was 12.24×106m3 and the average annual deposition thickness was 0.41 cm. From 2006 to 2009 the net erosion over seabed was 14.7×106m3 and the average annual erosion thickness was 3.60 cm. Moreover, the erosion information from 2010 to 2017 can be discerned by the net erosion of 10.17×106m3 and the average annual erosion thickness of 1.33 cm over seabed. moreover, all of 10 m isobaths migrated seaward from 1931 to 1970 and part of 10 m isobaths migrated seaward from 1971 to 2005 while 5 m and 10 m isobaths from 1971 to 2017 generally moved landward. Accordingly, it is expected that the study area will exhibit a weak erosion in the future. That the frequent storm surges leads to the regular instability of the seabed and the sharp decrease of suspended sediment discharge from the Yangtze River leads to the insufficient sediment supply may be responsible for the present erosion in the study area.
Key words:  marine geology  erosion and accretion  suspended sediment discharge  sediment transportation  Cangnan sea area

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