Multiscale soil-landscape process modeling

This chapter deals with the aspects of scale in soil-landscape modeling and presents a thorough review of the importance and effect of scale, including space and time resolution and the extent of space and time. The introduction covers the importance of the landscape in soil science and modeling throughout the past centuries, presents the aspects of soil-landscape modeling and scale issues, and briefly discusses sustainability and human influence, introduced as the fifth dimension. The general objective of this chapter is to illustrate the role of soils and geomorphological processes in the multiscale soil-landscape context. To illustrate and investigate this multiscale role, a simple model is used, with only a few parameters, which can be applied at different scales. Modeling results are given for the effects of changing spatial extension and resolution of a digital elevation model (DEM) and changing temporal extension (i.e., number of time steps) for these different DEMs' resolutions and extensions. The results are discussed in the context of scale problems occurring in hydrological and geo morphological modeling approaches, such as (1) emerging properties, (2) spatial heterogeneity of processes, (3) nonlinear behavior of process rates in time, (4) threshold dependency, (5) varying dominant processes, and (6) differing responses to disturbances. The example presented in this chapter, although with only a limited set of variables, indicates a spatial and temporal scale resolution- and extension-dependent response for different DEMs to the same set of input param eters, thus illustrating the multiscale character of the landscape and the existence of many of the well-known scale problems within the soil-landscape context