Semantic calibration of digital terrain analysis scale

Abstract

Digital terrain analysis (DTA) provides efficient, repeatable, and quantified metrics of landscape characteristics that are important to the Earth sciences, particularly for detailed soil mapping applications. However, DTA has not been field tested to the extent that traditional field metrics of topography have been. Human assessment of topography synthesizes multiple parameters at multiple scales to characterize a landscape, based on field experience. In order to capture the analysis scale used by field scientists, this study introduces a method for calibrating the analysis scale of DTA to field assessments. This method is used to calibrate land-surface derivatives of relative elevation, profile curvature, and slope gradient in the context of the commonly used field description of hillslope position. For a topographically diverse landscape in MI, USA, a peak in agreement between field assessment and DTA was found at field equivalent distances of 135 m for relative elevation, 63 m for profile curvature, and 9 m for slope gradient. Given the field experience of soil scientists, these calibrations of DTA metrics are likely to have stronger correlations with hillslope properties and could be used together to classify hillslope position consistently across large extents.