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exploring the effects of future policies and land use
practices on trajectories of ecological conditions is the
assessment of alternative future scenarios (Steinitz et al.,
1996, 2003, Hulse et al., 2004, Ahern 2001, Santelmann
et al., 2001). These future scenarios can be created by a
number of ways - citizen involvement, scientists, model
projections - and each method of scenario development
offers different strengths and weaknesses (Liu et al., 2007,
Henrichs et al., 2010).
Recently, use of environmental change scenarios has
increased, allowing scientists, managers, and the public
to anticipate future environmental conditions and their
effects on a wide variety of things people care about.
Scenario-based approaches are often used in research,
especially in multidisciplinary studies of landscapes and
river networks. Scenarios also offer a conceptual frame-
work for representing and modeling complex environ-
mental systems, with which the socio-economic impacts
of differing land and water uses can be assessed (Bouman
et al., 1999, Hubacek and Sun 2001, Bolliger et al., 2007).
As a result, these approaches are increasingly employed to
explore decision-making options for managing land and
water resources, as a means to integrate expert knowledge
of environments into policy making, and to investigate
the perceptions of local communities about their land-
scapes. Exploration and evaluation of future conditions
also provide a basis for assessing the vulnerability of the
landscape to future change and resource management
policies (Hulse et al., 2009, Lautenbach et al., 2009).
Application of remotely sensed information in the anal-
ysis of rivers and their basins is guided by the time frame
for the landscape characterisation, the method for project-
ing biophysical or human infrastructural characteristics of
the landscape, and the purpose for conducting a scenario-
based analysis of future landscapes. Landscape analyses
can depict the current properties of the landscape and
serve as a snapshot in time or they can depict past or future
landscapes in retrospective analyses and explorations of
future alternatives. All of these projections of landscapes
past, present, and future are scenarios - abstract repre-
sentations of mapped or remotely sensed information
that inherently include assumptions about the built and
biophysical features of the landscape. The purposes of
such studies, the processes of depicting scenarios, and the
methods of employing remotely sensed information all
shape the resulting credibility and nature of uncertainty
of the scenarios (Table 12.1).
12.1.1 Thepurposesof scenario-basedalternative
futureanalyses
Scenario-based analyses can serve different purposes: 1)
to support scientific exploration and research, 2) to
inform education and collaborative learning processes,
or 3) to underpin decision processes and strategic plan-
ning (Henrichs et al., 2010). For each example presented
in Table 12.1, we identified the most relevant purpose
according to types defined by Henrichs et al. (2010).
Examples of scenario analysis conducted for multi-
disciplinary scientific research are Lawler et al. (2006),
Aggett et al. (2009) or Baas et al. (2010). In this research
context, sensitivity analyses of critical parameters are
often employed (Lopez-Lopez et al., 2006). Risk and
sensitivity analyses attempt to measure the probability
and severity of adverse effects and assess how changes of
one specific factor (input, parameter, state etc.) affect the
response of a model.
A common type of scenario, which often is named
'business as usual' or 'plan trend', extrapolates future
trends of environmental parameters from past observa-
tions under the assumption of continued application of
current policies and management practices. Such scenar-
ios are typically used for collaborative learning, such as
Steinitz et al. (2003), Hunter et al. 2003), and Bolliger
et al. (2007).
Management agencies and local and regional gov-
ernments often use scenario analysis for planning and
decision making. These analyses differ in several ways, in
the methods used to develop and analyse scenarios, in the
approaches for integrating management alternatives, and
in the processes of stakeholder participation (USDA 1994,
Baker et al., 2004, Kepner et al., 2004, or Brierley et al.,
2009). The approaches may include public participation
processes (Baker et al., 2004), decision support systems
(Lautenbach et al., 2009), or multi-criteria assessments
(Nelson et al., 2009).
12.1.2 Processesofdepictingalternative
futurescenarios
Scenario analysis is a process for assessing the range
of possibilities by considering differing alternatives of
landscape evolution (Henrichs et al., 2010). Each scenario
represents a plausible description of a state, which is not a
forecast of the future state of a system, but an alternative
representation of possible trajectories of change. The
spatial scale of these scenario-based approaches can be
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