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. 2013 Oct 18;8(10):e76296. doi: 10.1371/journal.pone.0076296

Table 2. Topographic variables computed, with their formulas.

Topographic variable Formula [58] Hydrological significance (adapted from Moore et al. 1991)
slope Inline graphic Overland and subsurface flow velocity and runoff rate
aspect Inline graphic Solar irradiation
tangent curvature Inline graphic Erosion/deposition rate
contour curvature Inline graphic Converging/diverging flow, soil water content
mean curvature Inline graphic concavity/convexity
Laplacian convexity* Inline graphic valley bottom (positive values) vs. ridge top (negative values)

Inline graphic Inline graphic* The Laplacian convexity obtained after smoothing the elevation map with a Gaussian kernel is identical to the wavelet transform of the DEM with a Mexican Hat wavelet, except for a normalization factor [21].