| DEM分辨率对黄土侵蚀沟形态特征表达的不确定性分析 |
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| 引用本文： | 李思进,代文,熊礼阳,汤国安.DEM分辨率对黄土侵蚀沟形态特征表达的不确定性分析[J].地球信息科学,2020,22(3):338-350. |
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| 作者姓名： | 李思进 代文 熊礼阳 汤国安 |
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| 作者单位： | 1. 虚拟地理环境教育部重点实验室（南京师范大学）,南京 210023;2. 南京师范大学地理科学学院,南京 210023;3. 江苏省地理信息资源开发与利用协同创新中心,南京 210023 |
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| 基金项目： | 国家自然科学基金项目(41930102);国家自然科学基金项目(41971333);江苏高校优势学科建设工程资助项目 |
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| 摘 要： | 黄土侵蚀沟的地形表达是开展黄土沟谷侵蚀研究的基础工作,利用数字高程模型(DEM)定量描述侵蚀沟特征有助于研究侵蚀沟的形态变化和发育过程。基于DEM数据计算多种指标对黄土侵蚀沟特征进行描述是目前侵蚀沟研究中最为常用的方法。但是,受到格网DEM数据结构的限制,其计算结果会存在一定的不确定性。在侵蚀沟地形表达时,对形态特征的表达会受到DEM数据分辨率的影响,进而造成表达结果的不确定性。尤其在黄土高原地区,地形特征更为破碎,地形要素更为复杂,其表达结果受DEM分辨率的影响更为明显。本文以黄土高原典型样区为例,基于点云数据建立不同分辨率的DEM数据集,通过不同地形因子对侵蚀沟特征进行表达,分析DEM分辨率在黄土侵蚀沟形态特征表达时的不确定性。结果显示,分辨率的降低对主沟支沟比和纵比降等侵蚀沟形态特征因子产生了较大影响,且指标与分辨率多呈现线性变化关系。但是,随着侵蚀沟的横向扩张,DEM分辨率对其特征表达的影响逐渐被削弱。此外,在使用固定分析窗口进行侵蚀沟特征计算时,由于分辨率的降低,格网尺寸增大,其实际分析半径随之增大,使得计算范围内地表形态变化增加,导致沟谷切割深度随着分辨率的降低反而增加。同时,侵蚀沟主沟道区域受分辨率影响较小,沟头区域指标与分辨率的关系较弱。
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| 关 键 词： | 侵蚀沟 数字高程模型 形态特征 特征指标 DEM尺度效应 分辨率 不确定性 沟谷发育 |
| 收稿时间： | 2019-07-03 |
Uncertainty of the Morphological Feature Expression of Loess Erosional Gully Affected by DEM Resolution |
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| LI Sijin,DAI Wen,XIONG Liyang,TANG Guoan.Uncertainty of the Morphological Feature Expression of Loess Erosional Gully Affected by DEM Resolution[J].Geo-information Science,2020,22(3):338-350. |
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| Authors: | LI Sijin DAI Wen XIONG Liyang TANG Guoan |
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| Institution: | 1. Key Laboratory of Virtual Geographic Environment (Nanjing Normal University), Ministry of Education, Nanjing 210023, China;2. School of Geography, Nanjing Normal University, Nanjing 210023, China;3. Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing 210023, China |
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| Abstract: | Terrain expression of loess erosional gully is the base of the researches of gully erosion modeling and prediction, which also have a great significance in related fields of geoscience. The quantitative study of gully features based on Digital Elevation Model (DEM) can contribute to the research of morphological change and formation process of erosional gully. Currently, the use of representative feature indicators to describe the morphology of loess erosional gully should be one of the most popular used methods in researches of erosional gully. However, due to the structural limitation of grid DEM, the uncertainty widely exists in the calculated results based on DEMs. In previous practical researches, it has been proved that the resolution of DEM is an important factor which can influence experimental results obviously and cause the uncertainty of feature derivatives. Especially in the area of the Loess Plateau, the fractured landform and complicated landscape elements influence the expression of morphological features. Thus, the impact of DEM's resolution are more obvious in this area. The aim of this study is to analyze the uncertainty of morphological feature expression in the Loess Plateau based on DEMs with different resolutions. In this paper, DEMs with various resolutions of three study areas in the Loess Plateau were established based on the point cloud data which were acquired by Unmanned Aerial Vehicle (UAV). Eight typical morphological indicators were selected and calculated based on DEMs. These indicators were divided into groups according to the definition of each indicator. Two groups were established to express the morphological features of gully channel and gully head respectively. The experimental results shown that DEM's resolution has great influences on morphological feature indicators of erosional gully, and the major relationships between indicators and resolutions are linear. The high development stage of erosional gully's horizontal extension can weaken the influence of DEM’s resolution on morphological feature expression. In addition, when using fixed-size windows to calculate morphological feature indicators of erosional gully, the decrease of DEM's resolution lead to the increase of actual analysis radius and then surface morphological change has a growth trend in calculation areas. This phenomenon results in the rise of gully cutting depth when using DEM with lower resolution. Besides, the main gully channel is less affected by resolution. Thus, the DEM data with low resolution can be used to calculate morphological features of main gully channel. Finally, the morphological indicators of gully head were analyzed and there are weak correlations between these indicators and the resolution of DEM. |
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| Keywords: | erosional gully DEM morphological feature feature indicator scale effect of DEM resolution uncertainty gully development |
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