Optimization of interpolation parameters when deriving DEM from contour lines

Digital elevation models (DEMs) are still an important and current source of information for digital soil mapping and the modeling of soil processes. The grid DEM is often interpolated from contour lines. The contour sampling step becomes an additional interpolation parameter which can play an important role. The objective of this paper is to optimize the interpolation parameters of the Regularized spline with tension (RST) method, in order to prepare a DEM suitable as an input for erosion modeling. Two contrasting cases, with and without a reference DEM, were investigated. If a reference DEM was available, good results of interpolation were reached both by small and larger sampling steps. In the second case, it was found that small sampling steps should be avoided. The influence of the sampling was demonstrated by topographic potential for erosion and deposition.