Digital elevation model resolution: effects on terrain attribute calculation and quantitative soil-landscape modeling

The accuracy of digital elevation models (DEM) and DEM-derived products dep ends on several factors, including the horizontal resolution and Vertical p recision at which the elevation data are represented, and the source of the elevation data. This accuracy becomes increasingly important as we extend the use of DEM data for spatial prediction of soil attributes. Our objectiv e was to compare terrain attributes and quantitative soil-landscape models derived from grid-based DEM represented at different horizontal resolutions (10 and 30 m), represented at different vertical precisions (0.1 and 1 m), and acquired from different sources. Decreasing the horizontal resolution of the field survey DEM produced lower slope gradients on steeper slopes, s teeper slope gradients on flatter slopes, narrower ranges in curvatures, la rger specific catchment areas in upper landscape positions, and lower speci fic catchment areas values in lower landscape positions. Overall, certain l andscape features were less discernible on the 30-m DEM than on the 10-m DE M. Decreased vertical precision produced a large proportion of points with zero slope gradient and zero slope curvature, and a large number of steeply sloping and more highly curved areas. Differences among DEM from different sources were more significant, with less accurate representation of depres sions and drainage pathways with the USGS DEM as compared to the field surv ey DEM. Empirical models developed from different DEM included similar pred ictive terrain attributes, and were equally successful in predicting A-hori zon depth (AHD) in the validation data set. (C) 2001 Elsevier Science B.V. All rights reserved.