DEM分辨率对提取东北地区坡度的影响研究

目前国内外广泛采用的坡度-等效剪切波速关系模型中，坡度主要基于30″分辨率数字高程数据的提取。DEM分辨率对坡度的提取具有重要影响，且对于不同地区、地貌单元的影响不同。本文以我国东北地区1″、3″、30″分辨率DEM为基础，分别提取研究区域内公里网格点的百分比坡度，分析不同分辨率下提取坡度差异的原因。区分平原、丘陵和山地统计分析坡度随分辨率变化特征，通过比较多种拟合模型的拟合优度和坡度分级平均相对差值，给出不同分辨率下的最佳坡度转换关系。研究结果表明，坡度体现计算面积的平均特性，随着分辨率的增大，栅格计算面积减小，导致坡度有所差异，区域坡度变化越大差异越大；在我国东北地区，随着DEM分辨率的降低，坡度-频率分布曲线向低坡度段移动，且均值、方差及值域变小，不同地貌的坡度-频率分布曲线向低坡度方向移动，且峰值区域变窄，其中平原地貌变化趋势性显著，丘陵次之，山地最小；平原及山地地貌最佳坡度拟合为线性拟合，丘陵地貌下1″、3″与30″分辨率下最佳坡度拟合分别为线性拟合和多项式拟合。

Research on the Influence of DEM Resolution on the Slope Extraction in Northeast, China

The regional site classification method based on the slope has been successfully applied. The relationship model of slope-equivalent shear wave velocity based on 30 arc-second DEM is widely used at home and abroad. DEM resolution influences the extraction of the slope, and this influence is different in varying regions and landforms. Based on 1 arc-second, 3 arc-second, and 30 arc-second resolution DEM in Northeast China, this paper extracts the percentage slopes of the kilometer grid points and analyzes the reasons for the different slopes. Analyzing the characteristics of slope change with resolution in varying landforms, comparing the goodness of fit and the average relative difference, the best grade conversion relationship for different resolutions is selected. The results indicate the slope reflects the average characteristics of the calculated area. As the resolution increases, the grid area for slope calculation becomes smaller, which is the main reason for the different slopes. And the greater the slope of the area, the more significant the difference. With the decrease of DEM resolution, the frequency distribution curve of slope shifts to the low slope section, and the mean, variance, and range of values become smaller. The frequency distribution curves of varying landforms also move to the low slopes section, and the peak area becomes narrower. Among them, the changing trend of plain landforms is significant, followed by hills and mountains. The best fits for the slopes of plain and mountainous landforms are linear fitting. The best fits for slopes of 1 arc-second, 3 arc-seconds and 30 arc-seconds of hilly landforms are linear fitting and polynomial fitting, respectively.