海南岛四更沙及其邻近海域沉积特征与地貌动力演变

发布时间：2018-04-26 03:19

本文选题：沉积物分布 + 岸线演变　；参考：《华东师范大学》2016年硕士论文

【摘要】：近岸带地貌动力环境极为复杂,其动力、沉积和地貌演变需要深入的研究和理解。四更沙及其邻近海域位于海南岛西部,包含了典型的海滩、沙嘴、海湾系统和三角洲地貌类型。本文基于四更沙及其邻近海域沉积物粒度数据,并结合研究区动力条件和水深地形特征,研究表层沉积物的组分和类型分布、粒度参数及其沉积环境分区特征,并对其沉积物分布受控机制进行探讨。利用四更沙区域1972年以来8期Landsat影像,采用人机交互的方式提取干湿线,并以此作为岸线对昌化江河口三角洲海岸、昌化江口-四更沙嘴海岸、四更沙嘴海岸、四更沙嘴以南北黎湾海岸4个海岸的演变动态分别进行探讨。最后根据四更沙海滩表层沉积物分析和RTK高程测量数据研究四更沙海滩沉积物特征及地形演变规律。研究结果表明：①研究区沉积物类型多样,包括12种沉积类型,以砂质粉砂、粉砂、粉砂质砂和含砾砂为主,沉积物平均粒径变化范围较大(-0.70Φ-7.13Φ),且大体呈现由北向南逐渐变细的分布趋势。②运用Fleming的三角图式,结合物源状况及地形地貌条件,对沉积环境进行划分,将研究区划分为四更沙岸外海滨沉积区、北黎湾中部沉积区和八所港近岸沉积区等3个沉积区。③研究区沉积物分布特征受沉积物来源和水动力及地形条件共同影响。横向分布上,西部主要受强潮流输沙影响,东部近岸则主要受波浪掀沙和搬运作用影响,表现为两侧粗,中间相对较细的特征。纵向上,四更沙岸外海滨沉积区,沉积物主要受昌化江影响,粒径粗,表现为河口沉积特征；北黎湾中部沉积区,沉积物粒径分布范围广,表现为较强的过渡区特性;八所港近岸沉积区,沉积物粒径最细,泥沙来源主要为外海带来的泥沙。④昌化江河口三角洲海岸是岸线变化最为剧烈的区域,并主要表现为河口三大沙嘴的变化；昌化江口-四更沙嘴海岸,几乎所有自然岸线都表现为侵蚀,表现为淤积的只有因为沙嘴并陆的少部分自然岸线和人工围垦岸线；四更沙嘴面积不断增长,尤其是中部主体增长较快,沙嘴头部变动频繁,沙嘴根部则不断向东遭受侵蚀；四更沙嘴以南北黎湾海岸多为人工岸线,变化不大。⑤自南向北,纵向上看,四更沙海滩表层沉积物粒径大小呈现为粗-细-粗-细的变化规律。监测区受波流共同作用,水动力环境比较复杂,粒度分布较为分散⑥四更沙海滩季节性变化明显,凸出岸外岬角南侧的断面多表现为夏季淤积冬季侵蚀；海滩年变化来看,多为侵蚀海岸。上述研究将有助于复杂近岸过程的深入理解,同时可为四更沙及其邻近海域的开发和管理提供基础资料和科学依据。
[Abstract]:The geomorphologic dynamic environment of the coastal zone is very complex, and its dynamic, sedimentary and geomorphic evolution need to be deeply studied and understood. Located in the western part of Hainan Island, Sand and its adjacent waters contain typical beach, sand mouth, bay system and delta landforms. Based on the sediment granularity data of Sigansha and its adjacent sea areas, the composition and type distribution, granularity parameters and sedimentary environment zoning characteristics of surface sediments are studied in this paper, in combination with the dynamic conditions of the study area and the topography characteristics of water depth. The controlled mechanism of sediment distribution was discussed. The dry and wet lines were extracted by man-machine interactive method using 8 Landsat images in Sigansha area since 1972. The dry and wet lines were used as shoreline to the estuary and delta coasts of Changhua River, the estuary of Changhua River to the coast of Shizengshazui. The evolution dynamics of four coasts along the coast of South and North Lebanon Bay are discussed separately. Finally, based on the surface sediment analysis of Sigansha beach and RTK height survey data, the sediment characteristics and topographic evolution of Sigansha beach are studied. The results show that there are many types of sediments in the study area, including 12 sedimentary types, mainly sandy silt, silty sand, silty sand and gravel sand. The average grain size of sediments varies from 0.70 桅 -7.13 桅 to 0.70 桅 -7.13 桅, and the distribution trend of the sediment is gradually thinning from north to south. 2 the sedimentary environment is divided by using Fleming's triangular diagram, combining with the source status and topographic and geomorphological conditions. The study zonation is divided into four seashore sedimentary areas, three sedimentary areas, I. e., the central sedimentary area of North Li Bay and the nearshore sedimentary area of Bazhonggang. 3. The sediment distribution in the study area is influenced by the sediment source, hydrodynamic and topographic conditions. In the transverse distribution, the west is mainly affected by strong tidal current and sediment transport, while the east coast is mainly affected by wave sand lifting and transport, showing the characteristics of coarse sides and relatively fine middle. Longitudinally, the sediment is mainly influenced by Changhua River, and its grain size is coarse, showing the characteristics of estuarine sedimentation, while in the middle of North Li Bay, the sediment size distribution range is wide, and the sediment is characterized by strong transition zone. The sediment size is the smallest in the near shore sedimentary area of Bazhonggang, and the sediment source mainly comes from the offshore sediment 4.The delta coast of Changhua River estuary is the area with the most dramatic changes along the shore line, and mainly shows the change of the three major sand mouth of the estuary. Almost all of the natural shorelines on the coast of Changhua Estuary and Szongshanzui are eroded, only because of the small part of the natural shoreline and the artificial reclamation shoreline of the sand mouth and the land; the area of the Sand nozzle is growing continuously. In particular, the main body of the central region is growing faster, the head of the sand mouth changes frequently, and the root of the sand mouth is continuously eroded eastward; the coast of the north and south of Lebanon Bay is used as the artificial shoreline in the fourth sewer, with little change of .5 from the south to the north. The grain size of surface sediment on the beach is coarse-fine-coarse-fine. The hydrodynamic environment of the monitoring area is complicated by the interaction of waves and currents, the distribution of granularity is more dispersed and the seasonal variation of the beach is obvious. The section on the south side of the protruding headland mostly shows summer siltation and winter erosion. Most of them erode the coast. The above research will be helpful to the further understanding of complex inshore processes and can provide basic data and scientific basis for the development and management of Sigansha and its adjacent sea areas.
【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P736.21;P737.1

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