Effects of spatial resolution on slope and aspect derivation for regional-scale analysis

When performing a regional-scale geomorphometric analysis, one might face a decision on whether to derive morphometric data from a low-resolution DEM or to calculate basic derivatives from a higher resolution dataset and average these data afterwards. This paper investigates differences between morphometric parameters (slope and aspect) derived from a resampled DEM and resampled morphometric data derived from a medium resolution DEM, with examples for three study areas in South America. Using a low resolution DEM for regional scale morphometric analysis is not an optimal choice, since slope attenuation will strongly affect the distribution of calculated values. Unless bounded by computational constraints, one should choose to derive basic morphometric parameters from higher resolution data, and resample it to a coarser resolution as needed.