Introduction - Environmental Modelling: Finding Simplicity in Complexity - page 4

is that it depends less on the interaction and interpreta-
tions of the modeller, in that emergence occurs through
the interactions at a local scale. In most systems, these
local interactions are more realistic representations of the
process than the reductionist approach that tends to be
conceptualized so that distant, disconnected features act
together. The reductionist approach therefore tends to
constrain the sorts of behaviour that can be produced
by the model because of the constraints imposed by the
conceptual structure of the model.
In our opinion, both approaches offer valuable means
of approaching understanding of environmental systems.
The implementation and applicationof both are described
through this topic. The two different approaches may be
best suited for different types of application in envi-
ronmental models given the current state of the art.
Thus the presentations in this topic will contribute to
the debate and ultimately provide the basis for stronger
environmental models.

different topics might require different approaches. As
much as we would have liked, the coverage here is by
no means complete and we acknowledge that there are
gaps in the material here. In part this is due to space
limitations and in part due to time limits on authors'
contributions. We make no apology for the emphasis on
hydrology and ecology in this section, not least because
these are the areas that interest us most. However, we
would also argue that these models are often the basis
for other investigations and so are relevant to a wide
range of fields. For any particular application, you may
find building blocks of relevance to your own interests
across a range of different chapters here. Furthermore, it
has become increasingly obvious to us, while editing the
topic, that there are a number of common themes and
problems being tackled in environmental modelling that
are currently being developed in parallel behind different
disciplinary boundaries. One conclusion that we would
reach is that if you cannot find a specific answer to a
modelling problem relative to a particular type of model,
then looking at the literature of a different discipline
can often provide answers. Even more importantly, they
can lead to the demonstration of different problems
and new ways of dealing with issues. Cross-fertilization of
modelling studies will lead to the development of stronger
breeds of models!
In Part III, the focus moves to model applications.
We invited a number of practitioners to give their view-
points on how models can be used or should be used
in management of the environment. These six chapters
bring to light the different needs of models in a policy or
management context and demonstrate how these needs
might be different from those in a pure research context.
This is another way in which modellers need to interface
with the real world - and one that is often forgotten.
Part IV deals with a current approaches and future
developments that we believe are fundamental for devel-
oping strong models. Again the inclusion of subjects here
is less than complete, although some appropriate material
on error, spatial models and validation is covered in Part I.
However, we hope this section gives at least a flavour of
the new methods being developed in a number of areas
of modelling. In general the examples used are relevant
across a wide range of disciplines. One of the original
reviewers of this topic asked how we could possibly deal
with future developments. In one sense this objection is
correct, in the sense that we do not possess a crystal ball
(and would probably not be writing this at all if we did!).
In another, it forgets the fact that many developments

1.4 How to use this topic

We do not propose here to teach you how to suck
eggs (or give scope for endless POMO discussion), but
would like to offer some guidance based on the way
we have structured the chapters. This topic is divided
into four parts. We do not anticipate that many readers
will want (or need) to read it from cover to cover in
one go. Instead, the different elements can be largely
understood and followed separately, in almost any order.
Part I provides an introduction to modelling approaches
in general, with a specific focus on issues that commonly
arise in dealing with the environment. Following from
background detail, which in turn follows the more basic
material covered in Mulligan and Wainwright (2012),
we have concentrated on providing details of a number
of more advanced approaches here. The chapters have
been written by leading modellers in the different areas,
and give perspectives from a wide range of disciplines,
applications and philosophical standpoints.
The 11 chapters of Part II present a 'state of the art'
of environmental models in a number of fields. The
authors of these chapters were invited to contribute their
viewpoints on current progress in their specialist areas
using a series of common themes. However, we have
not forced the resulting chapters back into a common
format as this would have restricted the individuality
of the different contributions and denied the fact that