Figure 2.

Variable Pearson correlation coefficient matrix. Notes: The diagonal line indicates the variable names and distribution density curves, the upper diagonal panel is the correlation coefficient matrix, and the lower diagonal panel is the scatter plot matrix between the variables. SCI, soil color index; SRI, soil red index. RVI, ratio vegetation index; DVI, difference vegetation index; NDVI, normalized difference vegetation index; EVI, enhanced vegetation index; SAVI, soil-adjusted vegetation index; MSAVI, modified soil-adjusted vegetation index; SATVI, soil-adjusted total vegetation index. CNBL, channel network base level; CND, channel network distance; CI, convergence index; PlC, plan curvature; PrC, profile curvature; TWI, topographic wetness index; VD, valley depth; RSP, relative slope position; LSF, length–slope factor.