Iterate on the scope of the problem to ensure feasibility and reduce if needed.

Subtask Description:
Iterate on the scope of the problem to ensure feasibility and reduce if needed.

Action points of the implementation:

reductions in the list of model state variables,
re-adjusting ‘virtual’ System extent to simplify boundary condition description whilst retaining all relevant functionality,
simplifying the representation of spatial heterogeneity within the model-to-be,
removing or simplifying subsystems from the model-to-be,
focusing on a single space and time scale, so eliminating some process descriptions,
adding variables, feedback loops, and process descriptions in order to include relevant key system features hitherto omitted.
Prioritize, on grounds of relevance and cost-effectiveness, the activities of data acquisition, new measurements, and use of auxiliary models.
List the human resources available to you (in terms of skills and person-months) for this project; estimate how much has been used so far.

Area:
Barcelona Coast, Spain.

Policy Issue:
Investigation of the effects of changes in water quality on the aesthetic & recreational aspects of the beaches.

Human Activities:
Large scale urban & industrial activity, tourism.

General Information:
The quality of the water in the various beaches is affected significantly during heavy storms. Wastewater treatment plants are unable to deal with the sudden increase of inflow and the capacity of storm collectors is often insufficient to temporarily store this water for later treatment. This results in large quantities of untreated wastewater being released into the coast, causing bacteria concentration to exceed safety levels thus obliging the beach authorities to temporarily prohibit bathing or just causing aesthetic degradation that prohibits beach users from bathing. Reduced use of the coastal water influences the beach users decision whether to stay at the beach or to leave, thus affecting the revenue received by the local businesses and being an important stakeholder concern.

Example of Implementation:
Dur ing SSA internal team meetings there have been various re-scaling of the virtual system and the conceptual model. The initial model included the river to the south-west of the city (the Llobregat), various spatial scales in the coastal water (currently limited to one spatial area), the influence of the position of the underwater waste discharge on water quality and the influence of eutrophication or HABs on the coastal water. The re-scaling was partly a result of lack of data (poor spatial resolution of turbidity and bacteria indicators) and partly due to the low influence the variables were expected to have on the outputs (position of wastewater discharge, the Llobregat).

Additionally the bacteria indicator to be used was initially proposed as those relevant for the EU Bathing waters directive (Intestinal enterococci and E. coli) but following consultation with the Catalan water authority (ACA) it become clear that this data did not exist historically for a sufficient period. Therefore, the team selected alternative indicators that had been collected for a sufficient period of time (fecal coliforms; total coliforms; fecal streptococci). There were considerable doubts regarding the proposed model and scenarios. At the specific point of design, it was possible that the scenarios included in the model will be outside the influence of the stakeholders: for example, the ability to change the capacity of the storm collectors; or to change the metabolism of the city so that the run-off has less affect on the turbidity of the coastal water.

The model is also only based on subjective opinion, with no existing models to corroborate the hypothesis. It is possible that there could be little influence of the quality of the coastal water on the beach users decision to visit or stay at the beach. Similarly there could be little net benefit or costs to the local businesses – even if the beach users leave the coastal zone, this could result in possible benefits for businesses away from the beach, within the city. There is also little data regarding how changes in the water quality would influence tourism in the wider area (i.e. within the city of Barcelona). Barcelona offers more than just beach and sun tourism, in fact it is a minor part of the appeal as a tourist destination.

Comments:
The iteration and rescaling process is usually taking place internally and does not leave “evidence”. It is though a necessary process that can help in rescaling the issue, identifying problems and adding or removing components in order to achieve certain goals in a more effective way.

Contact:
Ben Tomlinson, Tomlinson@icm.csic.es