黄岩岛环礁地貌近40年变化的遥感分析  

Analysis on the geomorphic changes of Huangyan Island based on satellite images over the past 40 years

作　　者：刘嘉鎏 黄荣永[1,2,3] 余克服 Liu Jialiu;Huang Rongyong;Yu Kefu(Guangxi Laboratory on the Study of Coral Reefs in the South China Sea,Guangxi University,Nanning 530004,Guangxi;Coral Reef Research Center of China,Guangxi University,Nanning 530004,Guangxi;School of Marine Sciences,Guangxi University,Nanning 530004,Guangxi)

机构地区：[1]广西大学广西南海珊瑚礁研究重点实验室,广西南宁530004 [2]广西大学珊瑚礁研究中心,广西南宁530004 [3]广西大学海洋学院,广西南宁530004

出　　处：《第四纪研究》2020年第3期775-790,共16页Quaternary Sciences

基　　金：国家自然科学基金重点项目(批准号:91428203);广西科技计划项目(批准号:AD17129063和AA17204074)共同资助。

摘　　要：重建珊瑚礁的地貌变化历史将有助于理解珊瑚礁对气候变化的响应规律。因此,本文选择以南海中部相对孤立、低潮时部分露出的黄岩岛环礁(15°09'N,117°45'E)为对象,基于1977年至2019年间的Landsat和Sentinel-2共22景遥感影像来探讨南海珊瑚礁地貌的变化历史与规律。首先结合实测水深数据探讨遥感影像灰度的变化与珊瑚礁地貌带分界线位置的对应关系;然后通过基于梯度矢量流的主动轮廓线模型(GVF-Snake)和手动边缘提取相结合的方式,提取出黄岩岛环礁主要的地貌带分界线;进而利用数字化海岸线分析系统(DSAS)定量分析这些地貌带分界线位置的变化,并利用线性拟合来探讨这些地貌面积的变化趋势。结果表明:1)黄岩岛外海与礁前斜坡分界线、礁前斜坡与礁坪分界线、潟湖坡与潟湖底分界线均具有向外海移动的趋势,它们的平均移动速率分别是0.36 m/a、0.06 m/a和0.23 m/a,而礁坪与潟湖坡分界线则具有向潟湖移动趋势,平均移动速率为0.16 m/a;2)潟湖底的面积和礁体总面积都呈现增加的趋势,潟湖坡的面积有减少趋势,礁坪的面积则在1977年至1997年间以114523 m^2/a的速率增加,其后在1997年至2019年间则以11289 m^2/a的速率减少。进一步分析认为,近40年来,黄岩岛珊瑚礁生态系统退化致使其造礁能力的减弱,加之海平面上升、风暴潮侵蚀、海水溶解等因素的综合影响,导致黄岩岛珊瑚礁面积减少。Coral reefs are among the most important geological,geomorphic and ecological features for South China Sea(SCS).However,due to the influence of climate changes,the coral reefs in SCS have degraded rapidly in recent decades.In this context,the response of coral reefs to climate changes has become a frontier scientific problem.As an important response mechanism,how geomorphic zones of coral reefs respond to climate changes was still poorly understood.Huangyan Island(15°09'N,117°45'E)is a relatively isolated atoll,which is an important part of the coral reefs in SCS.By reconstructing the geomorphic changing history of Huangyan island,this paper provided new insights on how geomorphic zones of the coral reefs respond to climate changes.To reconstructing the history of geomorphic changes of Huangyan Island,22 Landsat and Sentinel-2 satellite images from 1977 to 2019 have been collected.Firstly,the relationship between the gray scale change in remote sensing image and the geomorphic zone boundaries indicated by water depth was discussed;then,the geomorphic zone boundaries of Huangyan Island were extracted by combining the gradient vector flow based active contour model(GVF-Snake)and manual boundary extraction;thereafter,the Digital Shoreline Analysis System(DSAS)was used to quantitatively analyze the changes of these boundaries,and linear fitting was used to explore the change trends of the area of geomorphic zones.The results show that:(1)The boundary between the outer sea and the fore reef slope,the boundary between the fore reef slope and the reef flat,and the boundary between the lagoon slope and the lagoon bottom,were seen to move outward with the movement rates of 0.36 m/a,0.06 m/a and 0.23 m/a,respectively,while the boundary between the reef flat and the lagoon slope had a trend of inward movement with a rate of 0.16 m/a;(2)The area of the lagoon bottom and the total area of the atoll were increased at the rates of 12676 m^2/a and 39078 m^2/a,the area of the lagoon slope was decreased at a rate of 57362 m^2/a,

关 键 词：黄岩岛 珊瑚礁 地貌 遥感 气候变化 

分 类 号：P722.7[天文地球—海洋科学] P731.23