Models in Policy Formulation and Assessment: The WadBOS Decision-Support System - Environmental Modelling: Finding Simplicity in Complexity - page 340

Figure 21.3 The integrated WadBOS model represented at the highest level of abstraction. This is a screen dump of the system
diagram view of the user-interface (see below). The boxes represent submodels, the arrows show linkages and flows of data between
the submodels (Courtesy of RIKS).

21.5.1 Economicsubmodel WadBOS. The calculations proceed through a series of

interlinked relations on a monthly basis. In this text,
the example of the recreational boating sector (Recre-
atievaart) is given but the scheme of relations applies
to all other sectors too, with minor adaptations in the
terminology and definitions.
The effort ( Overnight stays, recreational boating )ofan
economic activity is determined by the available Infras-
tructure . Infrastructure for recreational boating is the
number of mooring positions in the harbours. For other
economic activities, it is, for example, the amount of
equipment on board of boats (expressed in horsepower)
to drag fishing nets or suck up and wash shells, or the
number of hotel beds available for visitors. In order to
operate the Infrastructure , a workforce is required, thus
determining the Employment in the sector. The deploy-
ment of Effort and the availability of recreants (in the
recreation sector), or resources to be extracted (as calcu-
lated in the Ecology subsystem), determine the extent of
the activity: Presence recreational boating (see Figure 21.5:
) for the recreational boating sector or, for example, total
catch for the mussel fishery. At a fixed rate of spending,
the recreational boaters generate a particular Revenue .

In the economic submodel (see Figure 21.3), all the
major economic activities present in the Wadden Sea are
represented at some level of detail. Shell mining, Fishery ,
and Recreation have currently been worked out in greatest
detail. Most activities carried out at sea are an input into
the local Industry and generate directly or indirectly
Shipping of Goods & People. Shell mining and Fishery
directly extract biological resources from the Wadden
Sea, while Recreation, Electricity (generation) and Defence
use the open space as their prime resource. Finally, Gas
mining taps underground resources andmay thus have an
impact on the Morphology of the seafloor. The presence
and the noise generated by nearly all activities affect the
Landscape : its ecological state, the species present and
its attractiveness to humans. Furthermore, each human
activity causes some form of Emission of pollutants into
the waters.
Most economic activities are modelled on the basis
of the Platvis economic fishery model (Salz et al ., 1994).
Thus, they all have the same general modelling scheme,
represented inFigure 21.4. This approach increases greatly
the consistency, the learnability, and the transparency of