等高线曲率是一个重要的地形属性，反应了地形表面在水平方向的凹凸性，表达了地表物质运动的发散和汇合模式。基于安塞县县南沟小流域的矢量等高线数据和DEM，分别利用圆拟合算法（相邻三点法、间隔三点法和最小二乘法）和曲面拟合模型（E模型、S模型和Z模型）提取等高线曲率，通过对实地地形的对比分析，结果表明：（1） 在矢量等高线数据的计算结果中，三点拟合法计算结果相比最小二乘法结果差异大，对等高线曲率空间格局分布描述更准确；（2） 最小二乘法计算的结果频数分布集中程度最高，两种三点拟合法计算结果频数曲线差别微小；（3） 在栅格数字高程模型的计算结果中，基于S模型计算结果在空间格局上较E模型和Z模型的结果差别大，基于E模型的计算结果对等高线曲率描述效果更好。结果能准确说明采用不同算法计算等高线曲率的差别，对在实际数字地形分析中有重要的意义，可为等高线曲率计算提供重要参考。
Contour curvature is one of
the fundamental topographic indicators that reflects the convexities in the
horizontal direction of the topographical surface and expresses the divergence
and confluence patterns of the motion of the surface matters. Calculating the contour curvature can measure the
information conversion rate of the DEM interpolated by the vector contours, and provide a reference for setting the appropriate
DEM resolution. This study based on
vector contour data and DEM of Xiannangou watershed in Ansai County, Shaanxi Province, China, using the circle
fitting algorithms (adjacent three-point method, interval three-point method and least square method) and surface
fitting models (Evans model, Shary model and
Zevenbergen model) to calculate the contour curvature respectively. The comparative analysis between the real topography
of the site and the computational results indicated as follows: (1) The results
from the three-point fitting method
are different from the results using the least squares method, and the former describes the spatial pattern
distribution of the contour curvature more accurately. (2) The frequency
distribution of the results calculated by the least squares method is the
highest, and the difference
between the frequency curves of the two three-point fitting methods is small. (3) In the calculation
results of the DEM, the results from the
S-model display a larger difference than that by the E-model and the Z-model in the spatial pattern. The calculation results based on the E-model have a better effect on the contour curvature
description. The difference
presented by this paper when using different algorithms to calculate the
contour curvature provides important reference in retrieving the contour
curvature information in the practical digital terrain analysis.
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