Comparison of Three Supervised Learning Methods for Digital Soil Mapping: Application to a Complex Terrain in the Ecuadorian Andes

Table 1

Terrain parameter calculation with SAGA GIS software.

	Parameter	Module	Reference	Saga author/year
1	Elevation (El)	Fill sinks	[9]	Wichmann 2003
2	Slope (α)	Slope, aspect, curvature	[10]	Conrad 2001
3	Aspect
4	Valley depth	Relative heights and slope positions	—	Böhner and Conrad 2008
5	Wind	Wind effect	—	Boehner and Ringeler 2008, Conrad 2011
6	CI	Convergence index	[11]	Conrad 2003
7	Specific catchment area	Flow tracing/kinematic routing algorithm (KRA)	[12]	Conrad 2001
8	OFD	Strahler order ≥5	[13]	Olaya 2004
		Overland flow distance to channel network	[14]	Conrad 2001 & 2011
9	SWI	Saga wetness index	[15]	Böhner and Conrad 2001
10	LS factor	Length of slope factor	[16]	Conrad 2003