Identification of the spatial distribution of soils using a process-based terrain characterization

A simple process-based terrain characterization model was developed to identify the occurrence of soils over a complex landscape. Its basic proposition is that soil distribution can be most efficiently identified by the separation of pedogeomorphological units where similar hydrological, geomorphological, and pedological processes occur. The proposed model is a three-dimensional extension of the nine-unit soil landscape model. The two-dimensional conceptual and qualitative model is reinterpreted in terms of continuity equations describing the distribution of soil materials over hillslopes, and is implemented in a geographical information system (GIS) through the analysis of a raster digital elevation model (DEM). The application of this model at the Empire Prairie in southern Wisconsin, USA, shows a good agreement with the results of a soil investigation. The difficulty in modeling the diverse geomorphological and pedological processes at low lying slope positions and the influence of relict pedological features on contemporary soil formation, however, remain unsolved. This model can consider the spatial variability of soils both at the continuous and discrete scales, and is easily transferable to other slopes in a predictive manner. It is further expected to provide a quantitative tool to characterize surface topography in terms of process identification and resource survey, and also a priori information for spatially distributed ecological and environmental models.