共查询到20条相似文献，搜索用时 15 毫秒
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1 Introduction Automated extraction of drainage features from DEMs is an effective alternative to the tedious manual mapping from topographic maps. The derived hydrologic characteristics include stream-channel networks, delineation of catchment boundaries, catchment area, catchment length, stream-channel long profiles and stream order etc. Other important characteristics of river catchments, such as the stream-channel density, stream-channel bifurcation ratios, stream-channel order, number… 相似文献
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流域水系自动提取在西苕溪流域的应用 总被引：7，自引：0，他引：7
论述了如何基于栅格DEM自动提取流域自然水系的原理、方法和流程.以西苕溪中上游流域为例,根据DEM精度、上游集水区面积阈值和下垫面地形的不同,对所提取水系进行了比较.针对在平均地形坡度小于3°的平坦区域所提取水系与实际河网偏差较大的问题,提出了利用主干河道和平原水系数字化作为约束条件生成河网的新方法. 相似文献
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There is a growing interest in investigating the accuracy of digital elevation model (DEM). However people usually have an unbalanced view on DEM errors. They emphasize DEM sampling errors, but ignore the impact of DEM resolution and terrain roughness on the accuracy of terrain representation. This research puts forward the concept of DEM terrain representation error (Et) and then investigates the generation, factors, measurement and simulation of DEM terrain representation errors. A multi-resolution and multi-relief comparative approach is used as the major methodology in this research. The experiment reveals a quantitative relationship between the error and the variation of resolution and terrain roughness at a global level. Root mean square error (RMS Et) is regressed against surface profile curvature (V) and DEM resolution (R) at 10 resolution levels. It is found that the RMS Et may be expressed as RMS Et = (0.0061 × V+ 0.0052) × R - 0.022 × V + 0.2415. This result may be very useful in forecasting DEM accuracy, as well as in determining the DEM resolution related to the accuracy requirement of particular application. 相似文献
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TANG Guo-an~ Josef Strobl~ GONG Jian-ya~ ZHAO Mu-dan~ CHEN Zhen-jiang~ 《地理学报(英文版)》2001,11(2):209-216
1 IntroductionDigital elevation model (DEM) is digital representation of relief. It is one of the most important components in the database of GIS. At present, DEM is playing a key role in the field of survey and mapping, remote sensing and almost all the terrain related geographical analyses. DEM can be grouped into regular grids (raster) and triangulated irregular networks (TIN). Both have their advantages and disadvantages in application. It is generally believed that grid DEM will … 相似文献
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DEM流径算法的相似性分析 总被引：4，自引：0，他引：4
流径算法是分布式水文模型、土壤侵蚀模拟等研究中的关键技术环节,决定着汇水面积、地形指数等许多重要的地形、水文参数的计算。本文以黄土高原两个典型样区的不同分辨率DEM为研究对象,对常用的五种流径算法(D8、Rho8、Dinf、MFD和DEMON)通过相对差系数、累积频率图、XY散点分布图等进行了定量的对比分析。结果表明:算法的差异主要集中在坡面区域,汇流区域各类算法的差别较小;算法差异在不同DEM尺度下都有所体现,但高分辨率下的差异会更明显;在地形复杂区域,多流向算法要优于单流向算法。研究也进一步指出汇水面积、地形指数等水文参数对流径算法具有强烈的依赖性。 相似文献
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DEM提取黄土高原地面坡度的不确定性 总被引：72，自引：0，他引：72
选择陕北黄土高原6个典型地貌类型区为试验样区,采用野外实测及高精度的1:1万比例尺DEM为基准数据,研究栅格分辨率及地形粗糙度对DEM所提取地面平均坡度精度的影响。结果显示,对于1:1万比例尺DEM,5 m是保证该地区地形描述精度的理想分辨率尺度;多要素逐步回归模拟的方法进一步揭示了DEM所提取的地面平均坡度误差E与栅格分辨率X以及地形起伏的代表性因子-沟壑密度S之间存在的量化关系为E = (0.0015S2+0.031S-0.0325)X-0.0045S2-0.155S+0.1625,该结果也为确定适用的DEM分辨率提供了理论依据。 相似文献
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TANGGuoan ZHAOMudan LITianwen LIUYongmei ZHANGTing 《地理学报(英文版)》2003,13(4):387-394
Slope is one of the crucial terrain variables in spatial analysis and land use planning, especially in the Loess Plateau area of China which is suffering from serious soil erosion. DEM based slope extracting method has been widely accepted and applied in practice. However slope accuracy derived from this method usually does not match with its popularity. A quantitative simulation to slope data uncertainty is important not only theoretically but also necessarily to applications. This paper focuses on how resolution and terrain complexity impact on the accuracy of mean slope extracted from DEMs of different resolutions in the Loess Plateau of China. Six typical geomorphologic areas are selected as test areas, representing different terrain types from smooth to rough. Their DEMs are produced from digitizing contours of 1:10,000 scale topographic maps. Field survey results show that 5 m should be the most suitable grid size for representing slope in the Loess Plateau area. Comparative and math-simulation methodology was employed for data processing and analysis. A linear correlativity between mean slope and DEM resolution was found at all test areas, but their regression coefficients related closely with the terrain complexity of the test areas. If taking stream channel density to represent terrain complexity, mean slope error could be regressed against DEM resolution (X) and stream channel density (S) at 8 resolution levels and expressed as(0.0015S2 0.031S-0.0325)X-0.0045S2-0.155S 0.1625, with a R2 value of over 0.98. Practical tests also show an effective result of this model in applications. The new development methodology applied in this study should be helpful to similar researches in spatial data uncertainty investigation. 相似文献
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不同分辨率DEM提取地面坡度的不确定性模拟:以在黄土高原的试验为例 总被引：1，自引：0，他引：1
Slope is one of the crucial terrain variables in spatial analysis and land use planning,especially in the Loess Plateau area of China which is suffering from serious soil erosion. DEM based slope extracting method has been widely accepted and applied in practice. However slope accuracy derived from this method usually does not match with its popularity. A quantitative simulation to slope data uncertainty is important not only theoretically but also necessarily to applications. This paper focuses on how resolution and terrain complexity impact on the accuracy of mean slope extracted from DEMs of different resolutions in the Loess Plateau of China. Six typical geomorphologic areas are selected as test areas, representing different terrain types from smooth to rough. Their DEMs are produced from digitizing contours of 1:10,000 scale topographic maps. Field survey results show that 5 m should be the most suitable grid size for representing slope in the Loess Plateau area. Comparative and math-simulation methodology was employed for data processing and analysis. A linear correlativity between mean slope and DEM resolution was found at all test areas,but their regression coefficients related closely with the terrain complexity of the test areas. If taking stream channel density to represent terrain complexity, mean slope error could be regressed against DEM resolution (X) and stream channel density (S) at 8 resolution levels and expressed as (0.0015S2+0.031S-0.0325)X-0.0045S2-0.155S+0.1625, with a R2 value of over 0.98. Practical tests also show an effective result of this model in applications. The new development methodology applied in this study should be helpful to similar researches in spatial data uncertainty investigation. 相似文献
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Slope is one of the crucial terrain variables in spatial analysis and land use planning, especially in the Loess Plateau area of China which is suffering from serious soil erosion. DEM based slope extracting method has been widely accepted and applied in practice. However slope accuracy derived from this method usually does not match with its popularity. A quantitative simulation to slope data uncertainty is important not only theoretically but also necessarily to applications. This paper focuses on how resolution and terrain complexity impact on the accuracy of mean slope extracted from DEMs of different resolutions in the Loess Plateau of China. Six typical geomorphologic areas are selected as test areas, representing different terrain types from smooth to rough. Their DEMs are produced from digitizing contours of 1:10,000 scale topographic maps. Field survey results show that 5 m should be the most suitable grid size for representing slope in the Loess Plateau area. Comparative and math-simulation methodology was employed for data processing and analysis. A linear correlativity between mean slope and DEM resolution was found at all test areas, but their regression coefficients related closely with the terrain complexity of the test areas. If taking stream channel density to represent terrain complexity, mean slope error could be regressed against DEM resolution (X) and stream channel density (S) at 8 resolution levels and expressed as (0.0015S2+0.031S-0.0325)X-0.0045S2-0.155S+0.1625, with a R2 value of over 0.98. Practical tests also show an effective result of this model in applications. The new development methodology applied in this study should be helpful to similar researches in spatial data uncertainty investigation. 相似文献
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A study on DEM-derived primary topographic attributes for hydrologic applications: Sensitivity to elevation data resolution 总被引：1，自引：0，他引：1
Primary topographic attributes play a critical role in determining watershed hydrologic characteristics for water resources modeling with raster-based digital elevation models (DEM). The effects of DEM resolution on a set of important topographic derivatives are examined in this study, including slope, upslope contributing area, flow length and watershed area. The focus of the study is on how sensitive each of the attributes is to the resolution uncertainty by considering the effects of overall terrain gradient and bias from resampling. Two case study watersheds of different gradient patterns are used with their 10 m USGS DEMs. A series of DEMs up to 200 m grid size are produced from the base DEMs using three commonly used resampling methods. All the terrain variables tested vary with the grid size change. It is found that slope angles decrease and contributing area values increase constantly as DEMs are aggregated progressively to coarser resolutions. No systematic trend is observed for corresponding changes of flow path and watershed area. The analysis also suggests that gradient profile of the watershed presents an important factor for the examined sensitivities to DEM resolution. 相似文献
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JAY GAO 《International journal of geographical information science》2013,27(2):199-212
This paper examines the impact of DEM resolution on the accuracy of terrain representation and of the gradient determined. The DEMs of three terrain types with diverse complexities were constructed from digitizing contours and then kriging. The accuracy (RMSE) of the DEMs was regressed against contour density (D) and DEM resolution (S) at six resolution levels. It is found that RMSE may be expressed as (7.274 1.666S)D/1000 with an R value of 0.9659. The representation accuracy decreases moderately at an intermediate resolution, but sharply at coarse resolutions for all three terrain types. Resolution reduction profoundly affects the gradient determined from the DEM. While exerting little influence on mean gradient, resolution significantly affects the standard deviation of gradient, especially for a simple terrain. The results obtained in this study may be used to determine the DEM resolution that is appropriate to the accuracy requirements of a particular user. 相似文献
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基于不同DEM数据源的数字河网提取对比分析——以韩江流域为例 总被引：4，自引：1，他引：3
基于HYDRO1K、SRTM3和ASTER GDEM三种DEM数据,利用BTOPMC地形子模型提取韩江流域河网,并作对比分析。结果表明:①SRTM3提取的河网精度最高,HYDRO1K相对最低。②DEM的垂直精度对提取的河网精度起控制作用。ASTER GDEM的水平分辨率较高,但垂直精度不如SRTM3,因而提取的河网精度不如SRTM3。③HYDRO1K提取大尺度流域河网具有一定的精度,但在地势平坦区域的效果较差,HY-DRO1K不宜用来提取小尺度流域河网。④由DEM提取的数字河网精度与当地的地面坡度以及处理DEM的填洼算法有关。 相似文献
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土壤数据空间分辨率对水文过程模拟的影响 总被引：6，自引：1，他引：5
分布式水文模型的应用,其准确性有赖于输入数据对流域特征的描述,尤其在大尺度流域,输入数据分辨率的增加是否必然改善模型的模拟效果是值得深入研究的问题。本文以鄱阳湖信江流域为研究区,运用SWAT模型为模拟工具,分析了土壤数据空间分辨率对径流、蒸发及土壤含水量等水文要素模拟的影响以及高精度土壤数据在大流域尺度的适应性。结果表明：不同分辨率的土壤数据对SWAT模型中水文响应单元的划分结果差异显著,但在径流模拟和蒸发计算结果中并没有表现出显著的差别;模型率定前后,低分辨率土壤数据的径流模拟结果略好于高分辨率土壤数据,但两者之间的差别不明显;模型模拟的土壤含水量差异显著,高分辨率土壤模拟的月平均土壤含水量整体大于低分辨率土壤模拟结果;研究还发现,模型的蒸发计算对土壤分辨率信息不敏感。本文研究意味着,大尺度SWAT模型的应用中,土壤数据分辨率的提高不一定会改善模型的模拟效果。在具体应用中,应考虑流域本身的尺度以及模拟精度的要求,选择合适分辨率的土壤数据,同时应结合模型原理和关键参数的物理含义来解释模拟结果。 相似文献
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Glenn O'Neil Ashton Shortridge 《International journal of geographical information science》2013,27(7):1292-1311
Absolute elevation error in digital elevation models (DEMs) can be within acceptable National Map Accuracy standards, but still have dramatic impacts on field-level estimates of surface water flow direction, particularly in level regions. We introduce and evaluate a new method for quantifying uncertainty in flow direction rasters derived from DEMs. The method utilizes flow direction values derived from finer resolution digital elevation data to estimate uncertainty, on a cell-by-cell basis, in flow directions derived from coarser digital elevation data. The result is a quantification and spatial distribution of flow direction uncertainty at both local and regional scales. We present an implementation of the method using a 10-m DEM and a reference 1-m lidar DEM. The method contributes to scientific understanding of DEM uncertainty propagation and modeling and can inform hydrological analyses in engineering, agriculture, and other disciplines that rely on simulations of surface water flow. 相似文献
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Monia Santini Salvatore Grimaldi Fernando Nardi Andrea Petroselli Maria Cristina Rulli 《Geomorphology》2009,113(1-2):110
Terrain analysis applications using remotely sensed Digital Elevation Models (DEMs), nowadays easily available, permit to quantify several river basin morphologic and hydrologic properties (e.g. slope, aspect, curvature, flow path lengths) and indirect hydrogeomorphic indices (e.g. specific upslope area, topographic wetness index) able to characterize the physical processes governing the landscape evolution (e.g. surface saturation, runoff, erosion, deposition). Such DEMs often contain artifacts and the automated hydrogeomorphic characterization of the watershed is influenced by terrain analysis procedures consisting in artificial depression (pit) and flat area treatment approaches combined with flow direction methods.In shallow landslide deterministic models, when applied using topographic dataset at medium scale (e.g. 30 m of resolution), the choice of the most suitable DEM-processing procedure is not trivial and can influence model results. This also affects the selection of most critical areas for further finer resolution studies or for the implementation of countermeasures aiming to landslide risk mitigation.In this paper such issue is investigated using as topographic input the ASTER DEMs and comparing two different combinations of DEM correction and flow routing schemes. The study areas comprise ten catchments in Italy for which hydrogeomorphic processes are significant. Aims of this paper are: 1) to introduce a parameter estimation procedure for the physically-based DEM correction method PEM4PIT (Physical Erosion Model for PIT removal); 2) to investigate the influence of different terrain analysis procedures on results of the slope stability model SHALSTAB (SHAllow Landsliding STABility) using remotely-sensed ASTER DEMs; 3) trying to assess which of terrain analysis methods is more appropriate for describing terrain instability. 相似文献
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本文分别利用光学立体和In SAR技术生成了东南极Grove山地区15 m分辨率的ASTER DEM和20 m分辨率的In SAR DEM。在利用ASTER立体像对生成DEM的过程中引入ICESat测高数据作为高程控制以减少错误匹配,提高DEM垂直精度;而在利用ERS tandem数据生成DEM后,选取ICESat测高数据对In SAR DEM进行倾斜面纠正,以消除基线不精确估计等带来的影响。通过与未作控制的ICESat测高数据进行比较,评价了两种DEM的精度并对误差进行了分析。同时,比较了两种DEM的差异,并分析了造成这些差异的原因,探讨了两种技术生成南极冰盖DEM的优势和不足。最后结合两DEM的优势,融合生成了Grove山地区高精度的DEM。 相似文献