Authors
Dale A. McCullough, Ph.D.
Report Reference
#88-03
Publication Date
January 1988
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A Systems Classification of Watersheds and Streams
Abstract |
| Adequate management and scientific investigation of
ecosystems depends on classification of landscape systems based on
all significant bio-physical and associated cultural properties. The
present classification is a hierarchical systems design that can be
modeled in terms of a natural system interacting with its level-specific
environment. A watershed system in this context is embedded in a landscape
environment organized into, for example, zonal and regional systems.
A system at any level is classified by its capacity and the capacity
of its environment, capacity defining temporally the scope of possible
system performances relative to the components, substrate, climate,
biota, culture, and water. This theoretical framework for examining
systems was translated into methods suitable for integrating the full
capacities of watersheds and for displaying the discrete and continuous
nature of watershed and stream system similarities. Classification
of land to a sub-zonal level with a full capacity description coupled
with analysis of watershed substrate variables provided an adequate
representation of watershed capacity. This was demonstrated by empirical
correlations of system components described in the literature, and
by the ability to predict soil properties from topographic characteristics
of land facets that are formed on a grid system overlaid on the watershed.
Watershed classes were shown to be a good surrogate for differentiation
of stream classes. Watersheds were analyzed by facet on a grid system
according to several substrate variables. Slope, aspect, altitude,
radiation intensity on the winter solstice and equinox, and soil series
occurrence by facet effectively sorted watershed and stream classes.
These same classes were also revealed by a more extensive set of variables
describing the statistical distribution of these primary variables
and some variables describing topographic roughness, form, and drainage
development. Spatial organization of the basin is a significant factor
determining solar radiation distribution on slope facets and in segments
of the drainage network. A gravity model of spatial organization of
soils is potentially a useful model for stream reach performances,
considering the reach environment as the upstream segment, network,
and watershed system. |
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