淤泥质潮滩冲淤时空分异的遥感研究- - 以苏北辐射沙脊群为例

As an important deposition and sensitive belt of sea and land interaction, the environment of tidal flat is easily affected by human activities and hydrodynamic conditions. In recent years tidal flat suffered erosion and deposition on different time scales affected by the sediment supply, hydrodynamic, human activities and other factors, which threated coastal ecosystems of environmental and engineering facilities differently. To grasp terrain , erosion and deposition of the tidal flat is very useful for the rational development of tidal flat resources. Silt tidal flat is characterized as muddy surface, densely covered and frequently varied tidal creeks.Therefore,the traditional field observation has been restricted by the difficulty of access. Elevation measurement of muddy tidal flat is difficult in the topographic survey area so the tidal flat elevation information of real-time and large-scale is scarcity. Remote sensing ,combined with in situ surveying, is an effective tool for monitoring the tidal flats which can be detected by visible and near infrared sensors..In this study, radial sand ridges of the South Yellow Sea, as the typical muddy tidal flat, is selected to explore using short-term, multi-temporal and multi-source remote sensing image as the data source, combined with ground spectral features, and integrated use of the dynamic deposition and dynamic geomorphology , GIS and DEM, field observations and numerical simulation, qualitative and quantitative methods, under the supported of the waterline technology and of the hydrodynamic model, to build the history elevation model of the muddy tidal flats of radial sand ridges within 30-years and then to calculate the average deposition rate of the different part of study areas.Based on these analysis datum we can analyze the spatial differences and influencing factors on the tidal flat erosion/deposition.The result of this study can provide an important evidences for the tidal flat resource development and environment protection.

潮滩作为海洋与陆地交接的重要沉积地带，是海陆相互作用最活跃的区域。近来啦，受泥沙供应、水动力、人类活动等因素的影响，潮滩存在不同时间尺度的侵蚀和淤积现象，沿岸生态环境及工程设施受到不同程度的威胁。掌握潮滩地形信息及冲淤演变情况对合理开发潮滩资源非常有益。淤泥质潮滩高程测量是地形测量的困难区域，现势性强、大范围的潮滩高程信息稀缺。本研究拟以我国典型淤泥质潮滩-苏北辐射沙脊群为研究区，探讨以短时距、多时相多源遥感影像为数据源，结合地面实测光谱特征，综合运用动力沉积和动力地貌、GIS技术和DEM模型、现场观测资料与数值模拟、定性和定量相结合的方法，在水边线技术及水动力模型的支持下，构建30年来苏北淤泥质潮滩历史高程模型，计算研究区不同部位的多年平均沉积速率，分析潮滩冲淤的空间差异及影响因素，为淤泥质潮滩的可持续利用提供科学依据，为海岸带土地利用、海岸工程建设等提供基础数据与决策支持。

在大量野外调研、典型剖面测量、不同潮滩环境高光谱测量的基础上，通过水边线提取及构建不同时期数字高程模型，对江苏中部典型潮滩30年来的冲淤变化、辐射沙脊群及两大沙洲的动态冲淤演变进行研究，得到如下几点研究结果：① 江苏海岸线以射阳河口为界，分为两种类型。射阳河口以北是侵蚀型岸线，以南是淤涨型岸线。从二十世纪九十年代开始，由于沿海经济快速发展，人类活动影响加大，岸线迅速向海一侧移动，以梁垛河口-弶港的三仓河口淤涨速度最快，年均淤涨速率为185m；②随着江苏经济的发展及沿海大开发的需要，江苏潮滩弶港岸外大规模围垦，对条子泥动力地貌环境产生重要影响。条子泥潮滩-沙洲系统呈现局部潮沟频繁摆动、滩面破碎散乱的动态演变特性。条子泥沙洲面积的变化主要受沙洲北部西洋水道的影响。③将二分水作为标志性地貌单元，结合水边线提取方法，用多时相遥感影像资料定量研究潮滩演变及冲淤变化，对实测资料短缺的辐射沙脊群区域具有实用价值。④30年来，东沙主沙脊线呈南北向延伸，主沙脊线的南部和北部情况不一样，南部变化剧烈，移动幅度较大，北部变化平缓，移动幅度小；主沙脊线南部东移最大值出现在33°1′43″N，往东移动了约6000m。⑤现代辐射沙脊群以沿岸和东北部淤积为主，沙脊群中心枢纽部位冲淤变化较为频繁，外海大部分区域较稳定；北部西洋区域以冲刷为主，东北部冲淤相间，枢纽区冲淤变化明显，局部淤积厚度达到6 m以上，多处冲刷超过6 m以上。⑥辐射沙脊群北部和外围部分海域侵蚀作用强，不会再形成新的沙脊，小的沙脊遭遇侵蚀，将逐步消失，物质向岸滩或区域中心迁移。侵蚀过程有利于保持深槽的稳定性，但沙脊物质迁移过程可能会使地区部分航道位置发生淤积，影响通行。近年来地区港口、航道开发活动较为频繁，对此需引起注意。