CHAPTER 4
CHARACTERISTICS OF SOIL WATER MOVEMENT IN UNDISTURBED SOIL COLUMNS
Introduction
A model is the representation of a form or process in an
alternative media. In modern science, chemical and physical processes
are modeled by representing behavioral processes with mathematical
relationships based on empirical and theoretical concepts. Models of
natural systems are frequently quite complex, because numerous
interrelated processes must be considered.
The ultimate goal in the conceptual development of a model is the
integration of mathematical relations that represent the true
mechanisms of the natural process. However, mechanistic approaches are
limited by insufficient understanding of processes and/or their
interactions. The limitations take the form of unverifiable
assumptions and exclusion of known but seemingly insignificant factors.
In lieu of mechanistic descriptions, processes may be lumped such that
the mathematical expression reflects the relation of several different
and detailed processes. Such a deterministic approach is advantageous
when the effects of a process can be modeled but the actual mechanisms
are unknown, or when a true mechanistic model requires extensive
characterization of the modeled media.
The value of a model lies in its ability to simulate the natural
process from measured or estimated parameters that characterize the