Towards a new framework for modeling the soil-landscape continuum

This paper provides: (i) a brief historical review of soil-geomorphological approaches to investigations of soil-landscape formation, and (ii) an outline of a methodological and conceptual approach for three-dimensional (3-D) modeling of the soil-landscape continuum that utilizes geographic information systems (GIS), spatial analysis and field data. Four interrelated, iterative stages for developing 3-D models of the soil-landscape are outlined. The stages are designed to be explicit and applicable to the scale accuracy specified by the user. The first involves assembly and analysis of pertinent data to characterize a physiographic domain. The second stage is a geomorphometric characterization of the landscape from digital terrain models, which provides (i) a land surface representation to which other data are referenced and (ii) a division of the land surface into areas that correspond with soil patterns. The third stage uses georeferenced sampling as a basis for defining soil horizons, their attributes, and spatial arrangement in the landscape. The use of soil horizons rather than pedons as primary extrapolative units is a departure from traditional methods, but is central to developing a 3-D approximation of the soil diversity in the landscape. The fourth stage addresses the basic structure of the model to provide insight about (i) the range, variance, and correlation of soil and associated landform attributes and (ii) the pedogeomorphic processes that formed the landscape. The four stages may be viewed as an integrated procedure for defining explicitly decisions/assumptions, data analysis, visualization, and quantification of the scale and frequency of horizon patterns in three and four (time) dimensional landscapes.