Environmental Engineering Reference
In-Depth Information
UPPER WHARFEDALE VIEWED AS A SYSTEM
Like all physical landscapes in the real world, the landscape of Upper Wharfedale is very
complex, and seems to become more complex the more the physical geographer delves
below the surface. In this way, physical geography is no different from many other
academic subjects and organizations in the world. The field and methodology of
systems
analysis
have developed in 1970-2000 to investigate such complexity.
A system is a set of interconnected parts which function together as a complex whole.
Energy and matter move through systems by flows, cycles, transformations and a series
of stores, and produce forms (landforms, ecosystems, soil profiles) which are interrelated
and interacting. Frequently it is convenient to subdivide the whole environmental system
of the drainage basin into interconnected
subsystems
, i.e. individual units of which a
system is composed. Thus in the drainage basin it is possible to recognize the climate
subsystem, the land surface subsystem, the vegetation subsystem, the soil subsystem, the
aeration zone subsystem, the groundwater subsystem and the channel subsystem.
Why did a systems viewpoint become the norm in physical geography during the
period 1970 to 2000? Traditional approaches seemed to be leading nowhere, except to
large and larger lists of descriptive facts, with few ideas on what processes were at work.
The emphasis of research moved more and more to investigating the dynamic behaviour
of systems (geomorphic systems, hydrological systems, soil systems, ecosystems,
atmospheric systems) as opposed to the description and classification of landforms,
water, soils, vegetation and climates. In short, physical geography has become a dynamic
process-based subject in recent decades (Chorley and Kennedy 1971; Trudgill 1977;
Phillips and Renwick 1992). In addition to a concern for measurement, quantification and
modelling, the systems approach is important in two ways. First, it emphasizes
interactions among all elements in the landscape. The assumption is that a process or
feature can be understood only as it interacts or adjusts to other processes or features in
the physical environment. Secondly, a systems approach is concerned with whole
systems rather than one or two component parts. This is the
holistic
approach, in contrast
to the
reductionist
approach, which concentrates on one or two components only. The
holistic study of complex systems became a major feature of science in general in the last
three decades of the twentieth century.
The account of the Upper Wharfedale environmental system portrayed in the opening
is essentially a descriptive account in words and diagrams. In order to determine
quantitatively the rates at which processes are operating in the real world, measurements
would need to be taken by fieldwork and field experimentation. For example, the free
faces or 'scars' on valley sides often have small screes at their base. One asks the
question: how are the features of the free faces related to the screes? They occur together
in the landscape but how closely are their characteristics related?
These and similar questions are best answered if the free faces and screes are regarded
as a structured system. Figure 1.4 shows the morphological characteristics or form
attributes that could be measured in fieldwork. The relationships shown by the lines
linking the properties indicate where the correlations are statistically significant, together
with an indication of whether the correlation is positive or negative (+ or −). For
example, the height of the free face is positively correlated with scree height (i.e. the
bigger the free face, the bigger the scree), whereas the long axis (size) of debris is
