Environmental Engineering Reference
In-Depth Information
related to the budgets of landscapes or catchments, these small items have to be
integrated to build up a landscape picture. But as the spatial scale increases, new
processes arise, which were not evident at the smaller scale; for instance erosion,
groundwater flow or airborne transports connect patches in a horizontal manner.
Thus for the respective model analysis, a multi-scale approach has to be used with
emergent processes at each level (see Chap. 22 for more examples).
Models Can Support Decision Making Processes
Besides their potential in basic research, ecological models can also be very helpful
tools in decision making processes (also see Chap. 22 on Integrated Environmental
Models). Often the environmental manager can hardly foresee the effects of certain
measures for the states of environmental or social-ecological systems. To reduce
this uncertainty, models can illustrate assessment components. In this context
scenario modelling is playing a very important role. In that case the model con-
straints are defined due to the representation of different assumptions on environ-
mental situations, management options or political strategies. From the model
application the potential effects can be illustrated and an optimal strategy can be
selected. On the other hand, model applications are usual parts of our everyday life;
think of the weather forecasts, the characterisations of economic developments or
the multiple economic applications of programmes to show what might happen if
certain constraints of a system are changed. A most influential example can be
taken from global climate models (Fig.
2.8
). The predictions of future trends of
global temperature rise, depending on different mitigation strategies, are basic
elements of global political decisions.
2.4 The Limitations: What Models Cannot Do
Now that we have seen the potential of ecological models, it is also necessary to
mention some limitations of models as well.
Limits in Predictability
Ecological models are not a new form of alchemy. You cannot put in cognitive lead,
tin, and other low value materials, expect the computer to do magic and hope for
intellectual gold as a result. The potential of modelling has limitations, and the
“garbage in - garbage out” principle holds. Enthusiasm about modelling sometimes
tends to obscure that. Modelling can expand knowledge; however, it cannot replace
it. It can derive implications of given knowledge and it can be used to test interactive
hypotheses. Because of the complex interactions that take place in ecological
