Abstract:
Many environmental problems seem intractable because scientists, researchers
and decision-makers do not make connections between interacting system
components. For instance, most estuarine systems have inherent vulnerabilities that
can only be understood through study of interconnected social, ecological and
geophysical subsystems; failure to appropriately integrate subsystems can result in an
insufficient grasp of the complexities within human-environment systems.
The two research questions guiding this thesis research are: “How do humanenvironment
interactions influence directions of change in estuarine systems?”, and
“Is evaludation, in conjunction with other qualitative and quantitative methods, a
suitable approach to assess a transdisciplinary model?” The thesis introduces a new
methodology for investigating the controlling dynamics of these types of systems
using transdisciplinary, agent based modelling (ABM). Through questionnaires,
members of the public in the study area in north-eastern New Zealand identified
several types of environmental change in estuaries, five of which were used as model
foci: sedimentation, sea level rise, temperature changes, rainfall/runoff changes, and
blooms/hypoxia/die-offs. A new model, the Human-Environment Estuarine Systems
Investigator (HEESI), was developed to improve system understanding around these
five public interests.
HEESI is described using the ODD protocol of Grimm et al. (2006; 2010) and
tested using evaludation (Augusiak et al., 2014) in conjunction with workshops,
Monte Carlo simulations and associated statistical testing. Results are presented using
a scientific storytelling approach. This combination of techniques simply and
succinctly describes complex system interactions, and identifies non-linear,
unexpected outcomes. This is the first time evaludation has been applied to a
transdisciplinary whole-system human-environment model, and the first time that a
narrative approach has been used alongside statistical analysis and graphical depiction
of model pathways to identify directions of system change.
HEESI’s strength lies in its ability to investigate directions of change in
estuaries resulting from interactions between different subsystems in a way that
single-discipline models cannot. Directions of change emerge through complex
interactions, with drivers in one subsystem generating effects in other subsystems and across the whole system. Model outcomes highlight how anthropogenic activity can
lead to changes to estuarine ecology and geomorphology, with cascading effects on
social attributes. Other scenarios suggest ways in which geophysical differences
between systems may result in changes to social and ecological attributes. All
scenarios demonstrate the complexities and intertwined nature of human-environment
estuarine systems, and the potential for transdisciplinary modelling to improve system
understanding for researchers, stakeholders, decision-makers and the public.