Decision Making for Sustainable Use and Development - Coastal Lagoons: Ecosystem Processes and Modeling for Sustainable Use and Development - page 341

of changing input variables. This provides the necessary basis from which to analyze
the costs and benefits of each alternative choice. A model, therefore, provides a
predictive tool to the decision makers for use in their DSS, a tool that can predict the
outcome of many different possible choices. Even though the results are predictive
and not certain, they provide the decision maker a greater understanding of the eco-
system and the consequences of changing input variables. See Chapters 3 through 6
for examples of and references to watershed models.
Decision makers should weigh the cost and benefits of their preferred alternative
choices before making a final decision. Estimation of the economic value of each of
the goods and services provided will supply critical data for a cost-benefit analysis.

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The use of a model to predict outputs of the SES should provide the basis for estimating
both the ecological and economic changes expected. As a model predicts new outputs,
these changes in the NC will need to be recorded as assets or liabilities for the affected
economy. Each change in the model's input variables has a corresponding output
change in the NC that needs to be documented in economic terms. Assigning monetary
values to all goods and services is the critical link in providing more complete data
for decision makers to determine the consequences of their actions in terms of benefit
or loss to public or private financial interests (Figure 8.4) .

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An example of how an integrated management of surface water model can be used
in decision making can be found in Mailhot et al. A number of land use scenarios

such as timber harvest, agricultural practices, industrial, and urban land activities are
modeled to show the varying outputs according to the change in land use or practice.
Another example of a watershed model is the Patuxent Watershed Case Study
(PLM), which combines general models of ecosystem and economic site-specific
processes with remote sensing and GIS data on land use changes.

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This case study
demonstrates simulation of detailed spatial dynamics of the watershed including the
interaction of ecological and economic components and provides the link between
science and policy. Another general model that might be useful in describing the
ecological interrelationships can be found in the general ecosystem model (GEM).
Chapters 2 through 7 provide a variety of other specific models that address and best
model the units described in each chapter.

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8.4.2 M D -M T

ONITORING AS A ECISION AKING OOL

Monitoring provides specific answers for specific questions posed about the specific
aspects of a lagoon system; therefore, proper design of a monitoring program is
essential for providing the right data to answer these specific questions. Monitoring
collects selected data, with specific quality, format, collection, storage, and analysis
guidelines, specifically designed to answer the questions desired to describe the
status of the lagoon. The thoughtful and planned choice of variables to measure over
time will provide decision makers and managers with the information needed to
assess the status of a lagoon as well as to progress toward any goals and objectives
set for the lagoon system plan. Therefore, informed decisions can best be made
through a properly designed monitoring program and protocol including the selection
of the most appropriate parameters. GEO 2000 recognizes effective monitoring as
one of the most important needs in advancing sustainable development. When a

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