ZHU Qifeng,YANG Qinke,LONG Yongqing,et al.Preliminary Properties and Precision Analysis of Elevation Gradient Algorithm[J].Research of Soil and Water Conservation,2017,24(04):19-26.
高程梯度性质和算法不确定性的初步分析
- Title:
- Preliminary Properties and Precision Analysis of Elevation Gradient Algorithm
- Keywords:
- elevation gradient; elevation gradient algorithm; statistical distribution; stability of algorithms
- 分类号:
- P208
- 摘要:
- 高程梯度指高程在平面坐标中x和y两个方向上的变化率。在坡度算法θ=（p2+q2）/2中分别用p和q表示，因为高程梯度p和q算法的不同而衍生出多种坡度算法，因此对p，q算法性质和精度的研究是坡度算法精度评价的基础。选取陕西省绥德县、秦岭、黑龙江省拜泉县的三个样区，基于7种不同算法计算了高程梯度（p和q），并对其统计分布特征、空间结构特征、p和q相互关系、算法稳定性与不确定性等进行了分析。结果表明：（1）p和q均值为零，相互独立，方差相等，呈正态分布；（2）各种算法均能表现局地结构和样区之间的差异；（3）从算法稳定性、精度等方面看，Evans-Young算法，特别是经过Shary改进的Evans-Young算法的效果最佳。
- Abstract:
- Elevation gradient is the ratio of the elevation in x & y direction of Cartesian coordinate system, usually they are denoted as p and q in the general algorithm of slope steepness, i. e. θ= (p2+q2)/2. The differences of varied slope algorithms are mainly due to the different algorithms of p and q, and therefore, the accuracy of slope steepness depends on the precision of p and q algorithms. p and q have been calculated and analyzed in seven p/q algorithms in three sample sites, including Suide and Qinling of loess hills in Shaanxi Province, Baiquan of undulate hill in Heilongjiang Province. The analysis includes statistical distribution and spatial pattern (or structure) of p and q, the interrelation of p and q, the stability and uncertainty of algorithms. The results show that: (1) the mean values of p and q are almost zero, p and q are independent from each other, the variance of p and q are equal, and they follow the pattern of normal distribution; (2) all algorithms can represent the local structure and the differences among the sample sites; (3) with respect to the algorithm stability and uncertainty, Evans-Young algorithm, especially the improved Evans-Young algorithm by Shary is the best.
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备注/Memo
收稿日期:2017-01-13;改回日期:2017-02-21。
基金项目:国家自然科学基金（41371274；41301284）；陕西省自然科学基础研究计划（2014JQ5182）
通讯作者:杨勤科(1962-),男,陕西陇县人,教授,博士,主要从事侵蚀地形分析和区域土壤侵蚀评价。E-mail:qkyang@nwu.edu.cn