基于数字海图及遥感的近60年崇明东滩湿地演变分析

利用9幅崇明东滩湿地1951-2006年海图数据,10幅MSS,TM及ETM+卫星数据,采用水边线及等深线叠加技术,将湿地陆面及水下部分作为相互关联的整体,定性与定量相结合,综合分析崇明东滩湿地近60 a的演变.结果表明:①东滩湿地目前的演变过程已趋于稳定,在长江口河势稳定的情况下,将保持“南冲北淤、部分交替、中部淤涨”的态势;②人类活动是东滩湿地自然演变的重要驱动力,白港潮汐通道的封堵使东滩湿地成陆过程大大加快,东滩湿地0m线较为稳定地向东部扩展,在人类逐年围垦活动的干预下,湿地面积虽然逐年增加,但潮间带结构已偏离湿地自然状态,高潮滩面积所占比重减少,且成不连续分布,海堤直接暴露于外部海洋环境中,将降低对灾害天气的防御能力.     

植被对潮沟发育影响的遥感研究——以崇明东滩为例

根据现场测量,通过高分辨率航空图像提取崇明东滩潮沟的空间形态、植被类型及植被盖度指数。结合多时相卫星图像及海洋数值模式,利用水边线法及宽深比法反演潮沟沟底高程并构建了研究区潮沟三维地形,分析了植被对潮沟发育的影响。结果表明:1潮沟反演的均方根误差为0.545 m,且高潮滩反演精度高于低潮滩地区;2从低潮滩到高潮滩的潮沟深度先增大再减小,主要原因是高潮滩水动力条件较弱,加之植被根系的固滩作用,下蚀作用较弱,潮沟深度较浅,低潮滩由于水域开阔,水动力条件较弱,无植被覆盖侧蚀作用增强,潮沟变宽变浅;3潮沟深度空间分布表现出南深北浅的特征,崇明东滩潮沟密度与植被盖度呈现明显的负相关(r=0.560 4,p0.02),在高盖度植被覆盖的潮滩地区潮沟大多不发育,潮沟密度较低。潮沟长度与植被类型表现出较强的相关关系,在互花米草-芦苇群落为优势的区域潮沟长度普遍比以海三棱藨草群落为优势的区域长。     

基于遥感影像的北部湾金滩变化研究

以北部湾金滩砂质海滩为研究区域,以2000～2008年的28景Landsat-ETM+为数据源,通过多时相遥感影像水边线高程技术确定地形坡度,计算出金滩海滩高程变化、淤涨速度,得出坡度为2.3%,海滩同高程水边线向海方向推移速度为2.7 m/a,高程变化为+0.068 m/a。通过本研究,将从整体上把握北部湾金滩的变化特征,为开发建设金滩提供了参考依据。     

1986年以来杭州湾围垦淤涨状况卫星遥感调查

利用1986年以来8个时相的TM/ETM+遥感资料，调查杭州湾围垦淤涨情况。在几何校正、图像拼接的基础上，提取多时相的岸线； 利用GIS空间分析功能，分析岸线动态变化、围垦淤涨状况及其趋势。结果表明，1986年以来杭州湾岸线演化主要是由人工围垦和滩涂养殖引起。     

多元特征线遥感识别的滩涂DEM构建

针对水边线复合技术反演滩涂地形误差较大、经济成本较高等问题,提出了基于植被边线、冲淤痕迹线、水边线等多元特征线结合实测数据反演滩涂地形的遥感测量方法。以崇明东滩为研究对象,应用遥感技术提取水边线、植被边界线及冲淤痕迹线等多元特征线,利用实测数据拟合趋势线方法对边线高程赋值,并借助GIS空间分析技术将具有高程信息的特征线作为基础数据空间插值法构建滩涂DEM。最后,利用1∶1万地形图及实测数据对DEM反演结果进行质量评价。结果表明:该方法构建DEM影像数量需求少、时间跨度短、成本低、反演结果符合滩涂地形基本规律,垂直精度约为12 cm,研究结果对于滩涂冲淤变化及演变规律分析等研究具有重要的参考价值。     

崇明长江三角洲国家地质公园

位于上海长江入海口,公园选址于河口三角洲冲积沙岛-崇明岛东端,由团结沙、东旺沙、北八澈沙三沙合并而成。公园园区东西宽约25公里,南北宽约25公里,基本覆盖东滩自然保护区,总面积约145平方公里。崇明岛是世界最大的     

浙江东部穿山半岛岸线及潮滩演变的遥感调查

穿山半岛北侧是杭州湾的外海滨部分,其水动力条件、泥沙运移、沉积过程和地貌演变复杂。根据区域遥感影像和地理地形等资料,通过综合分析研究,探讨了穿山半岛北侧岸线和潮滩的变迁过程。研究表明,上世纪50年代穿山半岛北侧岸线大部分仍处于自然演变状态,从20世纪60年代开始,岸线向海迁移基本上是由工业填海和围海造田所致。潮滩总体呈现淤长的趋势,37a来,西侧滩界外移3050m,外移速率达+82.4m/a;向东,滩界变动范围逐渐减小。潮滩的发展具有空间、时间上差异性,潮滩淤涨集中在1955～1963年和1977～1982年。     

盐沼植被光谱特征的间接排序识别分析

运用ASD地物光谱仪,采用12个小型机载成像光谱仪(CASI)默认的植被波段组,以上海崇明东滩自然保护区的盐沼植物群落为对象,应用主成分分析法和相关分析研究了不同群落光谱特征与生态环境因子之间的关系。结果表明:运用PCA间接排序法能够识别盐沼植被中光滩、海三棱藨草群落、芦苇群落和互花米草群落等光谱特征;绝大多数盐沼植物的群落组成与所选波段的光谱特征之间有显著的相关关系;可见光和近红外波段数据可以分别识别低盖度的海三棱藨草群落和高盖度的互花米草和芦苇群落;对光谱反射率影响最大的生态环境因子是植物群落的高度和盖度,而高程和其它环境因子的影响次之。     

近40年椒江—台州湾滩涂围垦土地利用变化的遥感调查

利用1971年和1981年2版次地形图数据以及1981年、1990年、2001年和2011年4期遥感影像数据对近40 a来椒江—台州湾的滩涂围垦土地利用变化进行了调查。依据上述资料,利用GIS空间分析功能,获得了5期滩涂围垦土地利用现状及各期次之间的滩涂围垦土地利用变化转移矩阵。调查结果表明,近40 a来,椒江—台州湾滩涂围垦总体上呈增加趋势,土地利用变化的类型逐渐增多。1971—1990年间滩涂围垦土地利用类型多为耕地、养殖场和围垦用地;1990年以后,滩涂处于围垦开发利用热潮,光滩及围垦用地等多向耕地、居住用地、港口码头及养殖场等类型转化,而原本耕地及养殖场用地则多转化为居住用地。2001—2011年间,有80.77%的滩涂转化为围垦用地,光滩面积减少程度大,椒江—台州湾滩涂围垦扩张速度达到各时期最大值。     

Landsat影像的崇明岛滩涂冲淤演变特征分析

针对滩涂冲淤演变研究历史海图数据稀缺及遥感水边线高程赋值困难等问题，提出了基于长时间序列卫星影像的滩涂冲淤演变时空特征分析方法。该方法利用了平均大潮高、低潮位水边线具有稳定高程的自然属性，通过对特殊等高线几何特征与形态特征分析，研究了崇明岛滩涂冲淤演变的长期时空特征。结果表明：MIORSIW方法提取的平均大潮高、低潮位水边线高程精度优于0.15 m,分别以47.60 m/a和50.47 m/a的速度向外扩张；崇明岛滩涂局部表现出不同的冲淤特征，但整体处于淤积状态，以8.592 km²/a的速度增加；10～20 a后长江北支将断流，崇明岛东部滩涂发展速度放缓，形态上将和北岸大陆海岸线平齐，并最终与其合并。该文提出的方法操作简便快捷，解决了历史数据缺失问题，能够重现滩涂发展的历史形态、准确地给出滩涂冲淤长期时空演变规律，为滩涂资源的合理开发与保护提供了技术支持。     

Detecting coastline change from satellite images based on beach slope estimation in a tidal flat

Beach heights and tidal variation have large impacts on the accuracy of estimates of coastline position and its historical changes of a wider and flatter beach based on remote sensing data. This study presents an approach to analysis of waterline movement based on the beach slope, estimated from two effective images with Landsat images data. Two images acquired at different stages of the tide were processed to delineate accurately the position of the waterline. Then waterlines were assigned heights using elevations predicted by a two-dimensional non-linear tidal assimilation model. Beach slope can be calculated piecewise using the heighted shorelines based on the equiangular triangle theory. The positions of the national tidal height datum coastline can be obtained by the beach slope calculation method to accurately monitor the changing of coastline. A change in the coastline of the southwest tidal flat of the Yellow River delta, from Tianshuigou to the Xiaoqing River mouth, was detected by combining field measurements of profiles and bathymetric data. The root mean squared error (RMSE) of the calculated slope of the intertidal zone was one order of magnitude less than the measured slope. The minimum error of self-consistency check is 0.2%. The RMSE between the coastlines estimated by the proposed method and those surveyed data varies from 53.98 m to 217.72 m. It is shown that this method is more suitable for the two years and over the time scales of shoreline change monitoring. To assess erosion/accretion patterns in the tidal flat, and the controlling factors, the volume of the beach was investigated as a possible indicator. The accepted coastline position and changes in the beach volume were used to monitor the changing pattern of accretion and erosion along the coast southwest of the recent Yellow River mouth.     

潮汐和植被物候影响下的潮间带湿地遥感提取

潮间带湿地具有重要的生态和经济价值,但受到全球变化影响,发生大面积退化甚至丧失.掌握潮间带湿地的时空分布特征,对海岸带资源的科学管理具有重要意义.由于受到多云多雨天气和潮汐动态淹没的影响,单时相遥感数据难以获取完整的潮间带湿地信息.因此,本研究开发了一种基于时序遥感指数的潮间带湿地分类算法,并以福建省亚热带海岸带为例,...     

Prioritization of watersheds using morphometric parameters and assessment of surface water potential using remote sensing

In the present study, prioritization of sub-watersheds was carried out on the basis of sediment production rate. Further, basic hydrologic information such as peak rate of runoff and annual surface water potential were also assessed for the study watersheds and these are essential requisites for effective watershed management. The 10 sub watersheds of Tarai development project area are selected for the present study. Morphometric parameters pertaining to study area are used in the estimation of sediment production rate. The sediment production rate in the study area varies between 2.45 to 11.0 ha-m/100 km²/year. The remote sensing data has been utilized for generating land use/land cover data which is an essential prerequisite for land and water resource planning and development. The remote sensing data can especially play significant role in collection of real time information from remote areas of river basins for generation of parameters required for hydrologic modeling.     

基于Landsat影像的杭州湾最大浑浊带年际变化研究

杭州湾最大浑浊带（turbidity maximum zone,TMZ）受自然和人类活动的双重影响,年际变化显著。为探究杭州湾水域TMZ和表层悬浮泥沙浓度的年际变化特征,优选1984-2015年间30幅Landsat卫星影像,建立杭州湾水域表层悬沙浓度反演模型,模型经实测数据验证,平均相对误差为23.3%。对每张卫星影像进行悬沙浓度反演,进而提取TMZ面积数据。结果表明,杭州湾悬沙浓度面积分布类型均为正偏分布,且偏态系数由0.63增长至2.03,高悬沙浓度区域占比不断缩小。杭州湾各区域悬沙浓度均呈下降趋势,北岸芦潮港站下降趋势最为显著,减幅达73%。杭州湾TMZ面积年化下降率为4.57%,大于长江和钱塘江年输沙量的年化下降率3.74%。河流来沙减少和潮滩围垦导致的当地泥沙来源减少及水流携沙能力降低是影响TMZ面积降低的重要因素。     

Shoreline Change Analysis along the Coast of South Gujarat,India, Using Digital Shoreline Analysis System

Shoreline changes along the south Gujarat coast has been analyzed by using USGS Digital Shoreline Analysis System (DSAS) version 4.3. Multi-temporal satellite images pertaining to 1972, 1990, 2001 and 2011 were used to extract the shoreline. The High water line (HTL) is considered as shoreline and visual interpretation of satellite imageries has been carried out to demarcate the HTL based on various geomorphology and land use & land cover features. The present study used the Linear Regression Method (LRR) to calculate shoreline change rate. Based on the rate of shoreline changes, the coastal stretches of study area has been classified in to high erosion, low erosion, stable, low accretion and high accretion coast. The study found that about 69.31 % of the South Gujarat coast is eroding, about 18.40 % of coast is stable and remaining 12.28 % of the coast is accreting in nature. Field investigation was carried out which confirmed the coastal erosion/accretion derived from the analysis. The high erosion area are mostly found along the Umergaon (near Fansa, Maroli, Nargol, Varili river mouth, Umergaon light house) and Pardi (Kolak, Udwara)Taluka in Valsad district. Stable coastal length of the study area is 21.59 km and mostly found in Nani Dandi and near Onjal. High accretion (3.70 %) was only found near Hajira and low accretion (8.58 %) are distributed the study area. The main causes of coastal erosion of the study area were the strong tidal currents accompanied by wave action and reduced the sediment load of the river.     

Palaeo-path investigation of the lower Ajay River (India) using archaeological evidence and applied remote sensing

Numerous palaeochannels, oxbow lakes and elongated sediment fills in Eastern India, particularly along the lower Ajay River, provide a record of channel shifting during the Late Quaternary. Proper characterization of these features is useful for discussing the dynamic evolution of the river system in the Ajay-Damodar Interfluve region. Remote sensing data, archaeological evidence and sedimentology aid in reconstructing the geomorphic history of the lower Ajay River. Archaeological studies help in calculating the rate and direction of channel migration. The channel migration rate varies from 0.32 to 3.41 m/year in the study area. Bouguer gravity anomalies suggest that the rate of channel migration may be controlled by the density variations of the basement rocks. Furthermore, neotectonics activity played a significant role in the migration of Ajay River towards north-east direction.     

自下而上基于标准图幅的滩涂面积量算研究

滩涂面积量算是滩涂资源调查中的一项重要工作内容,其结果数据是调查成果的总体表现与直观反映,为滩涂围垦规划调整、围垦工程合理建设提供了数据支持。通过对标准图幅内的滩涂分布类型进行归纳整理,提出了一种自下而上基于标准图幅的滩涂面积量算方法：首先利用标准图幅内的等深线、岸线实现滩涂面的快速生成,其次计算滩涂面包含的水深点平均高程值判断滩涂类型,最后根据不同条件对滩涂面积分类量算统计。在2011年浙江省滩涂资源调查中的实践证明,该方法简单易用,具有一定应用价值。     

Change of river channel and bank erosion of the burhi dihing river (assam), assessed using remote sensing data and gis

The Burhi Dining river flows in a meandering course for about 220 km through alluvial plains of Assam including a short rocky and hilly tract in between. Sequential changes in the position of banklines of the river due to consistent bank erosion have been studied from Survey of India topographic maps of 1934 and 1972, and digital satellite data of 2001 and 2004 using GIS. Two broad kinds of changes have been observed, e.g. alteration of direction of flow due to neck cut-off and progressive gradual change of the meander bends that accounts for translational, lateral, rotational, extensional and other types of movement of the meander bends. Study of bankline shift due to the bank erosion has been carried out for the periods 1934–1972, 1972–2001, 2001–2004 and 1934–2004 at 13 segments spaced at 5′ longitude interval (average 15 km) as the river course trends nearly east to west. The amounts of the bank area lost due to erosion and gained due to sediment deposition are estimated separately. The total area eroded in both banks during 1934–1972 was more (26.796 km²) as compared to sediment deposition (19.273 km²), whereas total sediment deposition was more (34.61 km²) during 1972-2001 as compared to erosion (23.152 km²). Erosion was again more in 2001–2004 (7.568 km²) as compared to sediment deposition (2.493 km²). During the entire period (1934–2004) of study the overall erosion on the both banks was 31.169 km² and overall sediment deposition was 30.101 km². The highest annual rates of bank erosion as well as bank building of the river are 21055.47 m²/km in 2001–2004 and 9665.81 m²/km in 1972-2001, respectively. Similarly the highest average annual rates of erosion as well as sediment deposition in both banks are observed during 2001–2004 and 1972–2001, respectively. The hard rocks of the hilly tract situated in between result in development of entrenched meandering and this tract has suffered minimum bank erosion.     

辐射沙脊群海域悬沙场遥感反演方法

利用2006年江苏908调查水文泥沙测验数据和同期MODIS影像建立遥感定量反演模式,获取了半个潮周期的悬沙场以及全潮平均悬沙场,进行了辐射沙脊群海域悬沙场遥感反演方法的研究,并结合悬沙数学模型对结果进行了验证。研究表明,在辐射沙脊群海域,敏感参数(B1-B4)/(B1+B4)的对数模式反演悬沙场精度较高;遥感反演结果在总体上与数学模型计算结果相似,悬沙高值区主要分布在弶港、废黄河口和长江口附近;在细节上比数学模型表现得更精细,能清晰地反映河口、沙洲、水道等地貌对悬沙分布的影响。     

Radiometric mapping of the Berg River estuary

Geographic Information Systems (GIS) consists of various tools to perform spatial analyses in a wide variety of disciplines, including radiometric analysis to characterize the distribution of natural radionuclide concentrations. Recently, open-source GIS has become popular among geospatial users because it can be freely used, and powerful tools are constantly developed to enhance software capabilities. Gamma-ray spectroscopy was used to measure the concentrations of these natural radionuclides by dragging a Delta Underwater Gamma System (DUGS) among the sediment in the Berg River estuary located in Velddrif, South Africa. In this study, QGIS was used to visually illustrate and interpret the distribution of natural radionuclides, that is, potassium (K⁴⁰), thorium (Th²³²), and uranium (U²³⁸). These concentrations can be used to investigate various geographical and geological phenomena, which include sediment processes. The data were then interpreted to derive sediment characteristics. Various features of tidal estuaries were demonstrated by the results.