【作者】 徐伟；

【导师】 潘少明； 贾培宏；

【作者基本信息】 南京大学 ， 海洋地质， 2015， 硕士

【摘要】 沙坝澙湖海岸是世界沉积性海岸的主要组成部分,是目前国际陆海相互作用研究的重点区域。澙湖外侧沙坝能够阻挡波浪及风暴潮,湖内风浪平静风景优美,适合港口及旅游开发,湖中营养物质含量丰富是渔民的天然养殖场。近年,在人类活动的作用下,国内外部分沙坝澙湖海岸加速了消亡的进程。研究掌握我国海岸澙湖海岸的发育状况,探讨典型沙坝澙湖海岸的演变规律以及人为活动对其影响过程和作用机制,对未来沙坝澙湖海岸的合理开发与保护整治具有重要的指导意义。遥感(RS,Remote sensing)技术在对地观测时具有获取资料速度快、周期短、信息量大的优势,地理信息系统(GIS,Geographic information system)能对RS观测数据进行高效、精准的时空分析,RS/GIS技术适合长时间尺度的沙坝澙湖海岸地貌时空演化研究。新村、黎安澙湖位于海南岛东南部海岸,属于典型的沙坝澙湖—潮汐汊道环境,地貌类型丰富、自然景观独特,是国内乃至世界范围内不可多得地貌景观资源。2012年,海南国际旅游岛先行试验区落户陵水县新村及黎安片区,使之受到社会各界的关注。本研究以该处潮汐汊道澙湖海岸作为研究对象,利用多时相卫星遥感影像、历史海图资料、实测海洋基础数据,将遥感影像海岸带地貌信息提取、GIS三维地形模型时空叠加分析及数理统计分析等多种技术集成,通过定量化计算分析研究区沙坝澙湖岸线变迁、水下地形变化和澙湖沿岸地貌类型转化等,对近30年来陵水沙坝澙湖海岸地貌时空演化特征展开研究。研究结果如下:1.研究探索了利用遥感影像结合实测潮位及滩面实测高程数据提取澙湖平均高潮线位置,并以此位置为基础,统计获得缨帽变换后平均高潮线位置的湿度分量均值,进一步推算其他年份平均高潮线的技术方法。此方法弥补了长周期岸线演变研究中由于对应年份的潮位观测资料缺乏造成澙湖岸线难以提取的不足。2.借助多时相、长周期遥感影像提取澙湖岸线,通过对澙湖环形岸线的空间叠加及数理统计分析,有效识别提取出不同岸段人工岸线的空间分布情况及进退距离,发现自1987年至2011年近30年间,新村及黎安澙湖人工岸线长度已达到总长度的一半,并且岸线总体向湖心发生了较大规模推进,各测算样点的平均推进距离分别为94.04 m、102.56 m。新村澙湖面积从21.17 km2缩小至19.43 km2,共减少8.2%,黎安澙湖面积从9.94 km2缩小至7.92 km2,共减少20.3%。双湖沿岸的围垦与养殖开发已经对岸线及地貌的时空格局发生较大的影响。3.分析研究了新村澙湖1981年、2011年,黎安澙湖1985年、2011年两个时期水下地形模型的冲淤演变特征,并将其与对应实测湖底柱状样沉积物的沉积速率分析结果进行比对验证后发现:自80年代至2011年近30年间,双湖湖盆中央的水下平原区域发生大面积淤积,年均淤积厚度分别为新村1.72 cm/a,黎安1.56 cm/a。澙湖等深线的时空变化分析表明,新村口门外的落潮主水道在向南偏转摆动的同时不断冲刷加深。4.通过对研究区海岸地貌类型的实地勘查研究,建立了专业的沙坝澙湖海岸地貌类型分类标准,并以此标准为指导,展开遥感影像沙坝澙湖海岸地貌类型的信息分类与提取。通过地貌类型转移矩阵计算,发现1987年至2013年澙湖沿岸地貌发生显著变化,地貌类型转化趋势表现为海积平原、水下浅滩、海积阶地向养殖池及盐田转化,自然地貌间的相互转化不明显,大范围的潮滩围垦及海积平原挖掘改造形成了一条人工地貌带,割断了海积平原与水下浅滩之间的动力、沉积联系,改变了原有的物质交换模式,不断加强的人类活动已经成为该地区海岸地貌演变的主要驱动力量。以上研究结果表明,近30年来,持续并不断加强的人类活动对双湖地貌演化产生了明显的作用,湖面面积持续缩小、湖底沉积速率较快、水深变浅等,致使双湖海岸地貌的水动力作用方式发生改变,湖内水体交换周期变长,纳潮量降低,已对双湖沙坝澙湖地貌生态环境带来较大的负面效应。本研究结果可为未来人类活动对沙坝-澙湖海岸地貌演化影响过程及作用机理研究,以及先行试验区管理部门合理开发管理海岸带资源,制定区域海岸带可持续开发利用政策提供科学依据及数据技术支持。更多还原

【Abstract】 The barrier lagoon coasts are the important part of world coasts,thus they are ideal areas to study the interaction of land and ocean.The barrier of lagoon can block the waves and storm,wind and waves calm in lagoon.The nutrient content is rich in lagoon,so it’s suitable for aquaculture,port and the development of tourism.However,because of the disturbance of human activities,some of barrier-lagoon coasts have been destroyed seriously.Therefore,it would be of interest to learn how to grasp the development status of barrier-lagoon coast,investigate the evolution,affection process and dynamics mechanism of the typical lagoon.It also has significance to rational development and utilization of natural resources in coastal lagoons.The remote sensing(RS)technology has advantage to get materials in earth observation speed,short cycle,informative and not subject to any terrain conditions.Geographic information system(GIS)can perform precise and accurate analysis of spatial-temporal data.So the RS/GIS are very suitable for the spatial-temporal geomorphic evolution research of barrier-lagoon coast in decadal scale.Xincun and li’an lagoon are located in the southeast coast of Hainan island and there are typical barrier-lagoon coast systems and geomorphic type,which have rich and natural landscape unique.Therefore,this paper took the lagoons of Xincun and li’an as the studied area and based on the multi-temporal satellite remote sensing images,sea chart,topographic maps,measurement water depth and tide level,a geodatabase of coastlines,subaqueous reliefs and geomorphic patterns was established by using remote sensing interpretation and geographic modeling technology.In addition,the quantitative information of coastline,subaqueous relief and the geomorphic pattern changes was calculated by using the superposition of different period data.Some results are shown below.1.Using the remote sensing image of the lagoon mean high tide line position and the surface elevation data,we obtained the mean value of the high tide line position after the K-T transform.We further calculated the mean value of the high tide line for other years.This method makes up the flaw of traditional methods of the lack of the tidal observations for lagoon shoreline in the corresponding year.2.By using multi-time phase and long period remote sensing image,we analyzed the variation of lagoon shoreline during the past 30 years.The length of artificial shoreline has reached a half of the total length in Xincun and li’an and the total length of shoreline occurred promoting to the middle of the lake large scale.The average propulsive distances were 94.04 and 102.56 m respectively.Xincun lagoon area reduced from 21.17 km2 to 19.43 km2 and li’an lagoon area decreased from 9.94 km2 to 7.92 km2.The decrease in lagoon is 8.2%and 20.3%respectively.Along the shoreline,the spatial-temporal evolution geomorphology of barrier-lagoon coast have greatly influenced by the reclamation and aquaculture development.3.We analyzed the evolution of erosion and deposition of the underwater terrain model in two periods(1981 and 2011 of Xincun lagoon and 1985,2011 of Li’an lagoon)and measured sediments deposition rate of bottom column.The results showed that,two lagoons in the central basin of water occurred large area deposition and the average siltation thickness is 1.72 cm of Xincun and 1.56 cm of Li’an from 1980 to 2011.The analysis of the spatial and temporal changes in the lagoon bathymetric showed that the main ebb tidal channel of Xincun is constantly scouring the south while the swinging of the river is constantly washed.4.Through field survey in the study area of coastal landform types,we established professional criteria for classification of coastal geomorphic types.Using this standard,we extracted and classified the remote sensing image of the coastal geomorphic types of information landform types by the transfer matrix.The original geomorphic patterns around lagoons have profoundly changed by human activities from 1987 to 2011.Mutual transition for natural landform is very limited.A large area of tidal flat and marine deposition plain has been developed as artificial ponds between marine deposition plain and underwater bank.The original material exchange mode was changed.These results indicated that the evolution of lagoon landform has changed obviously by continuously strengthen human activities over the past 30 years.The lagoon area decreased continuously and deposition rates were relatively high.All these phenomena led to the change of hydrodynamic action way,extension of the lake water exchange cycle and reduction of the tidal volume.These bring negative effect on barrier lagoon landscape and ecological environment.Thus this research can provide scientific basis and technical support for the management of coastal zone resources and the development of starting pilot zone sustainable exploitation and utilization policy.更多还原