地球信息科学学报 ›› 2014, Vol. 16 ›› Issue (6): 882-889.doi: 10.3724/SP.J.1047.2014.00882

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不同尺度DEM的河流裂点提取及其效应分析

王婷婷(), 杨昕*(), 叶娟娟, 王琛智   

  1. 南京师范大学虚拟地理环境教育部重点实验室,南京 210023
  • 收稿日期:2014-01-06 修回日期:2014-03-19 出版日期:2014-11-10 发布日期:2014-11-01
  • 通讯作者: 杨昕 E-mail:wangtting1121@163.com;xxinyang@163.com
  • 作者简介:

    作者简介:王婷婷(1989-),女,山东临沂人,硕士生,主要从事DEM与数字地形分析研究。E-mail:wangtting1121@163.com

  • 基金资助:
    国家自然科学基金项目“基于DEM的黄土沟壑种群特征及空间异质性研究”(41271438);“基于DEM的黄土地貌沟沿线研究”(41171299)

Identification of Fluvial Knickpoints and Analysis of Its Scale Effect Based on DEMs

WANG Tingting(), YANG Xin*(), YE Juanjuan, WANG Chenzhi   

  1. Key Laboratory of Virtual Geographical Environment, Ministry of Education, Nanjing Normal University, Nanjing 210023, China
  • Received:2014-01-06 Revised:2014-03-19 Online:2014-11-10 Published:2014-11-01
  • Contact: YANG Xin E-mail:wangtting1121@163.com;xxinyang@163.com
  • About author:

    *The author: CHEN Nan, E-mail:fjcn99@163.com

摘要:

以不同尺度DEM数据提取裂点及其效应存在较大差异。本文以1:1万DEM为基础数据,通过小波分析生成多尺度DEM数据。以庐山地区16条河流为例,实现了多尺度DEM数据的河流裂点提取,探讨了河流裂点的变化规律,并构建了裂点个数的尺度预测模型。实验结果表明:(1)采用河道纵剖面与点坡降相结合的方法可快速准确地判断裂点;(2)在庐山地区,1:1万DEM数据可准确判断高差不小于5 m的裂点,对于高差小于5 m的裂点由于DEM表达精度和数据误差,而无法准确判定;(3)DEM尺度对裂点提取影响显著,裂点个数随着DEM分辨率降低逐渐减少,符合幂函数递减规律;(4)通过与ASTER GDEM和SRTM DEM对比验证,本文所构建的裂点个数与DEM尺度的拟合模型具有一定的预测精度。

关键词: 裂点, 多尺度DEM, 尺度效应, 庐山地区, 幂函数模型

Abstract:

Knickpoints are fundamental for understanding local erosion basis and the evolution of fluvial landforms. To extract the knickpoints, Digital Elevation Model (DEM) is widely adopted as the basic data in literatures. However, the accuracy of the extraction is greatly influenced by the DEM resolution. In this paper, to explore the influence of DEM resolution on the extraction of knickpoints, we analyzed the gradient of the fluvial longitudinal profiles to extract the knickpoints in Mount Lu area based on DEM and Digital Line Graphic (DLG). Firstly, the longitudinal profiles of the 16 streams with elevations are derived from 5 m DEM, from which the potential knickpoints are extracted from an empirical gradient domain. Secondly, to find a suitable gradient domain, a field investigation of four typical rivers, including Three-Step Spring and Crane Ravine, is carried out to collect the spatial positions of 30 knickpoints with GPS. Thirdly, multiple resolutions of DEM data are generated by wavelet transformation based on the 5 m DEM. The knickpoints in each scale are extracted in the same way from the corresponding DEM. Finally, the influence of the DEM resolution on the accuracy of knickpoints is discussed. The experiment results reveal that the suitable threshold of gradient domain for 5 m DEM is 0.6, by which the knickpoints’ altitude differences are greater than 5 m. The number of knickpoints is subject to a power function of the DEM resolution. As the DEM resolution coarsens, the number of knickpoints decreases. To verify this power function, the ASTER GDEM and SRTM DEM data are used, which reveals the consistency between the extracted knickpoints from the DEMs and the predicted ones from the function.

Key words: knickpoints, multi-scale DEM, scale effect, Mount Lu region, power function model