共查询到19条相似文献,搜索用时 703 毫秒
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平缓潮滩的测绘受到潮汐和淤泥的双重影响,难以进行大区域的人工作业。探讨利用序列遥感影像构建潮滩DEM的技术方法。基于多时相BJ-1小卫星自动提取水边线,利用中国近海高分辨率潮位网格,与卫星过境时刻的水边线进行空间关联与内插,生成带有高程值的系列水边点,并以此来构建潮滩地形三角网,最后生成格网潮滩DEM。与现场RTK验证的三个剖面的高程相比,其高程绝对误差均值小于0.2m。结果表明,应用中分辨率遥感影像进行淤泥质潮滩地形反演可以达到一定比例尺的制图精度。 相似文献
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本文应用河道固定断面高程数据和卫星遥感资料,建立了一种基于曲线正交网格的河道数字高程模型(DEM),进而进行河道冲淤定量计算的普适方法。应用1991—2012年黄河孙口-艾山河段河道断面高程数据,结合卫星遥感资料,分别应用本文方法、断面法和基于矩形网格的网格地形法计算了孙口-艾山河段的冲淤演化,比较了不同方法的差异,探讨了不同方法产生误差的主要原因,结果表明:基于三种方法计算得出的研究区河道冲淤演化趋势基本一致,但冲淤量差异较大。断面法计算结果与本文方法结果较为接近,平均相对误差约为9%,其计算误差主要源于未考虑河道宽度变化和断面方位与河道夹角的变化。基于矩形网格建模计算结果与本文方法结果相差较大,平均相对误差可达40%以上,主要由于现有断面数据空间分布不均匀,导致计算网格对于弯曲河道的控制不足,进而导致河道高程插值失真。本文方法考虑了河道河势与河长变化,计算网格与河道边界拟合较好,优化了河道高程插值方法,降低了断面方位对插值结果的影响,能够准确的计算河道的冲淤通量。 相似文献
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以盐城保护区核心区为例,利用2002年野外高程测量数据,运用Kriging和TIN两种不同思想的插值方法对研究区DEM的构建与精度评估两个问题展开研究.研究结果表明:1)Kriging插值验证显示:均差接近于0,均方根标准误差接近于1.证明采用Kriging插值同时考虑数据本身约束性条件的模型是可行的.同时,运用等高线和等高点数据生成的TIN,效果同样比较理想.2)对两种DEM进行了精度评估,数据显示误差都在可控范围之内.其中Grid-DEM的绝对误差最大值为0.162 m,平均绝对误差为0.063 m,平均相对误差为4.20%;而TIN-DEM的最大值仅为0.028 m,平均绝对误差和平均相对误差只有0.005 m和0.36%.3)在对两种DEM的比较中发现:无论是绝对误差还是相对误差,Grid-DEM都要远高于TIN-DEM,两者最大值相差0.134 m;在受人类干扰较强以及经常受潮汐影响而处于不断变化的区域,Grid插值要明显差于TIN插值.但从DEM表面整体光滑度来看,Grid-DEM却要优于TIN-DEM. 相似文献
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Avidesh Seenath 《Marine Geodesy》2013,36(6):581-604
AbstractThis article examines whether Digital Elevation Model (DEM) resolution affects the accuracy of predicted coastal inundation extent using LISFLOOD-FP, with application to a sandy coastline in New Jersey. DEMs with resolution ranging from 10 to 100 m were created using coastal elevation data from NOAA, using the North American Vertical Datum of 1988. A two-dimensional hydrodynamic flood model was developed in LISFLOOD-FP using each DEM, all of which were calibrated and validated against an observed 24-h tidal cycle and used to simulate a 1.5 m storm surge. While differences in predicted inundated area from all models were within 1.0%, model performance and computational time worsened and decreased with coarser DEM resolution, respectively. This implied that using a structured grid model for modeling coastal flood vulnerability is based on two trade-offs: high DEM resolution coupled with computational intensity, but higher precision in model predictions, and vice versa. Furthermore, water depth predictions from all DEMs were consistent. Using an integrated numerical modeling and GIS approach, a two-scale modeling strategy, where a coarse DEM is used to predict water levels for projection onto a fine DEM was found to be an effective, and computationally efficient approach for obtaining reliable estimates of coastal inundation extent. 相似文献
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A change in the elevation of bare tidal flats outside a mangrove area is an indispensable factor for the sustainable development of mangroves. Waterline extraction, as an effective and economical tool used in reconstructing the terrain of an intertidal zone, has been widely applied to open-coast tidal flats by constructing a digital elevation model (DEM). However, mangrove wetlands are usually located in wave-sheltered sites, such as estuaries and bays that have narrow tidal channels flanked by tidal flats. Changes in water level are affected by the dry-wet processes of complex landforms caused by tides. This article takes as a study case the area of Yingluo Bay, which covers the core region of the Zhanjiang and Shankou National Mangrove National Nature Reserve in southwestern China. Waterline extraction based on seventeen multisource and multispectral satellite images obtained from December 2014 to April 2015, combining the finite-volume coastal ocean model (FVCOM) hydrodynamic model in an iterative process, was used to generate a topographical map of the bare tidal flat outside the mangrove area in Yingluo Bay. The quality of the iterative DEMs was evaluated via six transects of a ground-based survey using Real - time kinematic (RKT) GPS in May 2015. The mean absolute error (MAE) and root mean square error (RMSE) of the DEM decreased with an increase in the number of iterations. In this study, the DEM in the third iteration was used as the final output because the difference from the previous iterative DEM satisfied an inversion-stopping criterion. The MAE and RMSE of the final DEM with the measured data were 0.072 and 0.09?m, respectively, without considering small tidal creeks. The method used in this study can be an effective and highly precise approach for detecting and reconstructing the historical terrain of a bare tidal flat outside a mangrove area. This work also has great importance regarding intertidal resource management and the sustainable development of mangroves facing the vulnerable coastal ecological environment. 相似文献
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The identification of potential coastal inundation caused by future sea level rise requires not only time series records from tide gauges, but also high-quality digital elevation models (DEMs). This study assesses the importance of DEM vertical accuracy in predicting inundation by sea level rise along the Valdelagrana beach and marshes of the Bay of Cádiz (SW Spain). A present-day (2000) and a projected (2100) high tide have been spatialized over a traditional (aerial photogrammetry) regional DEM of Andalusia with a horizontal spatial resolution of 10 m and a vertical accuracy of 0.68 m RMSE (root mean square error), and a LIDAR-derived DEM of the Valdelagrana study site with the same spatial resolution but a vertical accuracy of 0.205 m RMSE. The simulations are based on a bathtub model, which accounts for the effect of vertical barriers. The results reveal that the presence of infrastructures such as roads and salterns is the key to delimit the extent of water penetration during high tides in an otherwise homogeneously flat area comprising the beach and marshes of Valdelagrana. Moreover, in comparison with the highly accurate LIDAR DEM, the inundation areas derived from the lower-resolution DEM are overestimated by 72 % and 26 % for the present-day and future scenarios respectively. These findings demonstrate that DEM vertical accuracy is a critical variable in meaningfully gauging the impacts of sea level rise. 相似文献
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现代黄河三角洲地面沉降及其原因分析 总被引:9,自引:0,他引:9
为全面和具体地了解整个黄河三角洲的地面沉降状况,收集了现代黄河三角洲地区1956、1967、1980年1∶5万比例尺的地形图资料,利用地理信息系统软件进行数字化、建立高程数据库,生成数字高程模型。通过对不同时期数字高程进行空间运算发现,1956—1980年间黄河三角洲地区地面沉降现象普遍,沉降区年平均沉降数厘米。基于数字高程空间分析结果,探讨了诱发三角洲地面沉降的自然和人为因素。 相似文献
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The waterline detection method (WDM) based on satellite images is one of the most effective methods for constructing digital elevation models (DEMs) for tidal flats. The general practicability of the WDM has been demonstrated in previous studies for small areas. This article attempts to generate a DEM over a large offshore sandbank with a tidal flat area of more than 620 km2 by integrating the conventional WDM with a hydraulic model and multitemporal satellite images. For illustration purposes, a case study was conducted at the Dongsha sandbank, one of the largest sandbanks among the radial tidal sand ridges of Jiangsu Province, China. In this study, 34 multitemporal satellite images acquired at different tidal phases in 2006 were analyzed to detect the waterlines. The water level at each satellite overpass moment was simulated by a south Yellow Sea hydraulic model, and discrete waterline points were combined with the corresponding water levels to produce a topographic map. Compared with the DEM produced during the same period by the airborne light detection and ranging (LiDAR) data, the DEM derived from WDM effectively contains the average height error within 47 cm, which is satisfactory. All of these findings may be useful for researchers and local authorities, as the findings could be used as a reference for sandbank evolution research or to support environmental management, coast protection, and storm forecasting. 相似文献
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水边线法是潮间带地形遥感反演的重要方法。针对常规水边线方法在应用于地形多变的岸外沙洲潮间带数字高程模型(DEM)构建中出现的水边线交叉和缺乏表现潮沟微地形特征的问题,本文提出了一种增强型地形遥感构建方法:首先通过潮位排序,筛选出具有正确高程变化趋势、空间分离的水边线;然后对筛选过程中水边线位置相近的影像组按像元计算改进的归一化差值水体指数并进行均值序列合成,提取出合成海陆边界线,二者共同构建出初始的潮间带DEM;进一步利用低潮期的潮沟边界线和中线生成潮沟DEM,通过潮沟镶嵌处理,最终获得可表达滩面微地形起伏的潮滩DEM。该方法在江苏岸外辐射沙洲中部核心区域的模拟应用表明,对比4条验证剖面的平均结果,高程平均绝对误差为0.43 m,均方根误差为0.54 m,相关系数(r)为0.75,模拟高程与验证高程在剖面起伏形态变化方面具有良好的一致性,同时模拟DEM的空间破碎度小,能够反映更多的细节地形特征。该方法可为利用多源遥感数据构建考虑微地形变化的高精度潮间带地形DEM提供新的思路。 相似文献
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Waterline technique based on satellite remote sensing is potentially one of the most effective tools for studying changes in tidal flat environment and coastlines. However, multi-temporal waterlines obtained from satellite images are often difficult to compare directly because fluctuant tidal conditions may produce different elevation of waterlines. To overcome the difficulty, this study developed a comparable waterline solution to estimate active lateral evolutions using TM satellite images at different tide conditions. Owing to the dynamic properties, the Yangtze River mouth was selected as the case example to test the suitability of the approach, and totally four time slices were partitioned during 1987–2004 for investigating coastline changes. The first step of this technique is to digitize waterlines with various elevations labeling in a time slice. In the second step, the waterlines were merged to generate DEMs and contour maps using the linear gridding interpolation method. In the last step, any interested contour line may be extracted from DEMs and used for comparison of tideland changes. To evaluate the errors in digitizing and interpolation process, quantitative checks were examined after the DEMs were constructed. In order to monitoring the rate of coastline spread, a proposed approach for estimating mean coastline spread distance between two time spans is developed in this paper. To conclude, this work demonstrates the importance of TM/ETM images to provide high-frequency historical topography and morphodynamics information for coastal monitoring and evaluation. 相似文献
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To address the limitations of current methods to control and adjust the accuracy of depth models and relatively low accuracy, a quantitative method to control and adjust the accuracy of adaptive grid depth modeling is proposed. First, uncertainties in source data and interpolated depths are estimated, and the representation uncertainty derived from finite and discrete points representing the continuous seafloor surface is analyzed. Second, mean vertical uncertainty in an arbitrary given area is calculated. Finally, interpolation of the depths at grid nodes from source data and the distribution framework of the grid nodes are optimized in each local area, and an adaptive grid depth model is created according to the expected accuracy. The experimental results demonstrate that (1) the proposed method can control and adjust the accuracy of the depth model in each local area such that the accuracy of the constructed model meets the requirements of the expected index as closely as possible and (2) the proposed method can improve the accuracy of the depth modeling by optimizing the interpolation and distribution of the grid nodes. 相似文献