地理科学 ›› 2020, Vol. 40 ›› Issue (3): 455-465.doi: 10.13249/j.cnki.sgs.2020.03.014

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基于DEM的黄土沟谷横剖面形态特征研究——以宜君、延安、绥德为例

周毅1,2, 王泽涛1,2, 杨锋3   

  1. 1. 陕西师范大学地理科学与旅游学院,陕西 西安 710119
    2. 地理学国家级实验教学示范中心,陕西 西安 710119
    3. 北京师范大学地理科学学部遥感科学与工程研究院,北京 100875
  • 收稿日期:2019-02-04 修回日期:2019-06-12 出版日期:2020-03-10 发布日期:2020-05-13
  • 作者简介:周毅(1984-),男,河南南阳人,副教授,博士,主要从事GIS空间分析算法与黄土高原数字地形分析研究。E-mail: zhouyilucky@snnu.edu.cn
  • 基金资助:
    国家自然科学基金项目(41871288);国家自然科学基金项目(41930102);中央高校基本科研业务费专项资金项目资助(GK202003064);中央高校基本科研业务费专项资金项目资助(2018CSLZ002)

Morphological Characteristics of Gully Cross-section in the Loess Region Based DEM: Taking Yijun, Yan’an and Suide as Cases

Zhou Yi1,2, Wang Zetao1,2, Yang Feng3   

  1. 1. School of Geography and Tourism, Shaanxi Normal University, Xi’an 710119, Shaanxi, China;
    2. National Teaching Demonstration Center for Geography, Xi’an 710119, Shaanxi, China;
    3. Institute of Remote Sensing Science and Engineering, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China
  • Received:2019-02-04 Revised:2019-06-12 Online:2020-03-10 Published:2020-05-13
  • Supported by:
    National Natural Science Foundation of China(41871288);National Natural Science Foundation of China(41930102);The Fundamental Research Funds for the Central Universities(GK202003064);The Fundamental Research Funds for the Central Universities(2018CSLZ002)

摘要:

选用1:10 000高精度5.0 m分辨率的DEM数据,在陕北地区,按黄土地貌演化序列次序,遴选分别代表黄土残塬沟壑、梁状丘陵沟壑、峁状丘陵沟壑地貌的宜君、延安、绥德3个流域,研究其中1 831个沟谷横剖面19个因子的形态特征,利用主成分分析法确立核心因子,分析结果表明:沟谷深度、宽度、横剖面面积、宽深比、侵蚀度与不对称性指标的主成分累积贡献率为95.02%,为黄土沟谷横剖面核心指标; 随级别的增加,3个流域沟谷宽度、横剖面积、宽深比、侵蚀度均呈现总体增加的态势,与黄土地貌发育阶段具有明显的空间耦合性,尤其是宽深比与侵蚀度指标,反映出低级别黄土沟谷溯源侵蚀现象明显,以下切侵蚀为主,而高级别沟谷沟沿线后移,以侧向侵蚀拓宽为主的规律; 随级别增加沟谷深度呈现先增后降的态势,并在中级别沟谷出现拐点,与实地调研发现沟谷在中级别下切侵蚀遇到基岩的现象相吻合。

关键词: DEM, 沟谷横剖面, 宽深比, 侵蚀度, 黄土高原

Abstract:

Loess gully cross-sections carry greatly important information on evolution of loess landforms, gully erosion and sediment yield. However, systematically quantifying morphological characteristics of loess gully remains been poorly understood. The objectives of this study are to: 1) Analyze the characteristics of gully cross-section indexes (including basic gully cross-section indexes and compounded gully cross-section indexes) for different ranks of gully in the same sub-watershed, and for the same rank of gully in different sub-watersheds. 2) Reveal the relation of gully cross-section and loess landforms in different evolution stage. In this study, we choose Loess Broken Tableland (Yijun Watershed), Loess Ridge (Yan’an Watershed) and Loess Hill (Suide Watershed) as the study test sites, and classify the three watersheds into 5 ranks according to Strahler’s method. Our original studied data are 5 m-resolution Digital Elevation Models (DEMs) and the matched Digital Orthophoto Maps (DOMs) with 1 m-resolution. The DEMs and DOMs met the national standards of China; the DOM data was conducted by using of 5 m-resolution DEM. Based on 5 m DEM, we measured 19 indexes for 1 831 loess gully cross-sections in Yijun, Yan’an and Suide using GIS platform. Futher, we applied the principal component analysis method (PCA) to obtain 7 key indexes: namely, depth, width, cross-section eroded area, the ratio of width/depth, erosion degree, asymmetry ratio of side width and asymmetry ratio of side area of loess gully. The results demonstrate that: 1) The principle component analysis test showed that the cumulative contribution rate of depth, width, cross-section eroded area, the ratio of width/depth, erosion degree, asymmetry ratio of side width and asymmetry ratio of side area of loess gully already reaches to 95.02%. These indexes act as key indexes for characterizing loess gully cross-section. 2) With the increase of loess gully-rank, obvious increasing trends were detected in width, cross-section area, width/depth ratio, erosion degree of loess gullies. Besides, the trends of width/depth ratio and gully depth indexes indicate that low-ranks loess gullies present obvious downward erosion, whereas high-ranks loess gullies present lateral erosion accompanying with shoulder-lines retreating. 3) With the increase of loess gully-rank, the depth presents a trend of increasing firstly and then decreasing, and the turning points occur at intermediate-levels gully. The trend confirms the fact that intermediate-levels gullies have started to incise into bedrock.

Key words: Digital Elevation Model, gully cross-section, width/depth ratio, erosion degree, the Loess Plateau

中图分类号: 

  • P931.6