Table 3: Regression models to predict clay percent of the surface layer using terrain attributes and satellite images.

Class no.ConstantSlope (%) AspectCurvatureASTER MarchSPOT October

117.690.070.000020.120.250.54−0.004−0.0060.12
242.93 −0.750.311.08 0.040.50
339.16 0.00011.34 0.04−0.200.80
422.12 −0.00013.682.790.76−0.02−0.130.54
5−2.82−0.06−0.00012.741.940.15−0.01−0.040.38
653.77 −1.20 −0.20 0.0070.52
712.29 −0.000031.751.401.62 0.33

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