Table 5: Regression models to predict clay percent of the surface layer using terrain attributes only (without satellite images).

Class No.ConstantSlope (%) AspectCurvature

115.060.060.000010.230.270.610.10
246.18 −1.290.881.070.37
319.31 0.000060.29 0.68
43.44 −0.000082.683.172.370.46
50.97−0.11−0.00021.781.251.100.18
666.35 −2.30 −1.410.45
73.46 −0.000041.851.252.520.24

Significant at the 0.05 probability level; **significant at the 0.01 probability level.
As: upslope contributing area; CTI: compound topographic index.