[1]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.
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Research of Soil and Water Conservation[ISSN 1005-3409/CN 61-1272/P] Volume:
24
Number of periods:
2017 04
Page number:
19-26
Column:
Public date:
2017-08-28
- Title:
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Preliminary Properties and Precision Analysis of Elevation Gradient Algorithm
- Author(s):
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ZHU Qifeng, YANG Qinke, LONG Yongqing, WANG Chunmei, PANG Guowei, SHI Dong
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College of Urban and Environment Science, Northwest University, Xi’an 710127, China
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- Keywords:
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elevation gradient; elevation gradient algorithm; statistical distribution; stability of algorithms
- CLC:
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P208
- DOI:
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- Abstract:
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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.