Construct the Simulation Model

Subtask Description:
Construct simulation model by linking up the ESE models

Action points of the implementation:
The environmental, social, and economic sections of the model need to be finalized and brought together into a system based model before it can be used to inform stakeholders and decision-makers.

Result: Linked simulation model comprising of ESE component models joined together as a system model.

Area:
Guadiana Estuary, Portugal (& Spain).

Policy Issue:
Management of the discharges of untreated wastewater into the estuarine environment.

Human Activities:
Energy production, tourism, urban activity, agriculture and livestock farming, aquaculture.

General Information:
The estuary is the natural border between Portugal and Spain. On both sides of the estuary, especially in Spain, urban development is taking place, mainly associated with tourism and threatens to increase the input s of pollutants , namely nutrients and bacteria. Nutrient input is expected to change, not only due to fertilizer application on golf courses, but also due to the river discharge from a large dam, which has accumulated nutrients during its filling. On the Portuguese side , the construction of a large-sc ale WWTP, designed to serve several urban areas, was successively delayed since it is located within a protected area . The main stakeholder concerns relate to asymmetric development strategies of the two countries and the impact of activities taking place in the watershed on the estuarine and coastal water quality, which has consequences on tourism attractiveness, fisheries, or traditional salt farming.

Example of Implementation:

Relationships between the variables involved in the ESE model of the Guadiana Estuary.

ExtendSim screenshot of ESE model linking for the Guadiana Estuary.

The link between the environmental and socio-economic components (Fig. 7) was made under the assumptions that:

- An improvement in water quality (represented by the variable faecal coliforms concentration and N:P:Si ratios) leads to an increase in the economic benefits provided by that resource. These benefits have been calculated using contingent valuation methods (willingness-to-pay) for residents and visitors of Guadiana estuary.
- The estuary’s trophic state (N:P:Si ratio) affects fish populations which will have an economic impact on fisheries and, consequently, on related employment.
- Water quality has an impact on beach attractiveness that can be related to the number of visitors to the surrounding beaches and to employment.

A scheme of the technical linking done in ExtendSim is represented in Fig. 8. The main technical problem in order to perform the linkage was to harmonize the time step of the ecological sub-model (one day) and of the socio-economical sub-model (one year). The issue was solved using equation blocks containing ModL language that integrate the outputs of the environmental component and feed them to the socio-economic sub-model.

Contact: Carlos Sousa cssousa@ualg.pt , Helena Guimarães mguimaraes@ualg.pt , André Mascarenhas apmascarenhas@ualg.pt