Construct the Simulation Model

Subtask Description:
Review Inputs, linkages, outputs for the simulation model.

Action points of the implementation:
Ensure ability for the sub system models to be joined together, that there are common variables between models, which will result in the outputs of one sub model acting as the inputs to the other, and vice versa. Ensure models run on the same time step to enable the models to interact with each other.

Result: ESE component models running on compatible time steps and with links between those models identified.

Area:
Himmerfjärden , Sweden

Policy Issue:
Eutrophication status and reduction.

Human Activities:
Urban sewage discharge, agriculture and industrial activity, tourism.

General Information:
Nutrient loading has caused increased turbidity, loss of biodiversity, including submerged aquatic vegetation, deep water oxygen def iciency, phytoplankton blooms and biodiversity loss. The main stakeholder concerns are connected with tourism, recreational activities and nature enjoyment, and the sustainable implementation of WFD that poses economic challenges for several activities in the area.

Example of Implementation:

Ecological model: water exchange model simulating the response in terms of water transparency of the coastal system area to changes in nutrient loads.
Economic model/component: evaluate costs and benefits implied by scenario, i.e. for every policy option (mg N/l) within each scenario based on WWTP (HSTP in the diagram below), private sewer (PS) and wetland creation (AGR bellow). It aims to assess increased human wellbeing due to environmental improvements.
Social component: Measuring the social behavior. Social benefits are moneytarized and included into the economic component leading the economic model to a socioeconomic model. However, creating wetlands is a voluntary measure for farmers and factors affecting the willingness to participate in wetland creation is at the core of the social component through the definition of a participation function.

The socioeconomic model is linked to the ecological model by providing nitrogen reduction for each policy option, based on Secchi depth improvement and a demand function for recreation. The ecological model uses an empirical relationship between total nitrogen and Secchi depth to calculate average summer Secchi depth.

Secchi depth (m) versus total nitrogen concentration (µg/l)

The Secchi depth change indicates a changed human well-being (measured as contingent valuation) in the socio-economic sub-model.

The estimate of the total extension of wetlands that is likely to be created is linked to the ecological components by providing a figure of how many kg nitrogen that is likely to be reduced by the wetlands created, and to the economic component by providing a figure of how much the wetland creation will cost.

Other linkages connecting the systems are presentations of qualitative benefits of scenarios and how scenarios affect ecological indicators according to the WFD status classification system.

Conceptual model of linkages between social, economic and environmental components

The time step for all data used in the socio-economic model is one year. The time step in the ecological sub-model is days but an average Secchi depth value for the summer months in each year is imported into the socio-economic model. As a consequence the original annual reduction data for agricultural activities and private sewers has been divided in 365 for integration with the ecological sub-model.

Comments:
Integration of sub-models is a logistical problem which should involve ecologists, economists and sociologists. Identification of cause and effect linkages is a very challenging activity, particularly across a range of scientific sectors. Clear concepts are required to facilitate this. For example, a particular ecological change may lead to economic and then social change, which then feeds positively or negatively back into ecological status. These need to be undertaken in an open and discursive way, and agreements have to be reached before the next stage can be attempted.

Contact: Frida Franzen frida@enveco.se