Run Scenario Simulations

Subtask Description:
Prepare, conduct, and test scenario versions of the Simulation Model.

Action points of the implementation:
Scenarios should then be applied to the model in a simulation run. This represents outputs of your model and is the data which will be used in the output step to inform the stakeholder group of your findings.

Result: Simulation output values from the simulation model that reflect changes caused by applying the scenarios.

Barcelona Coast, Spain

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

Human Activities:
Tourism activities, recreational and commercial harbours, fisheries, urban activities, waste effluents and WWTP, heavy industries and agriculture.

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:
Scenarios concerning effects of sewerage management options on the Barcelona beaches: the baseline and six additional scenarios combining five options for both “the percent of combined sewer overflow released directly” and “the capacity of storm water collectors” are investigated.

Storm water collector scenarios – impact on suspended matter.

Storm water collector scenarios – impact on bacteria.

The model indicates that at the current percentage of direct release, tripling the capacity of storm water collectors will have no effect on suspended matter. The key variable is the percent of combined sewer outflow (CSO) directly released, and this only has a significant effect on the lower concentrations of suspended matter.

Conversely, both the percentage of CSO directly released and the capacity of storm water collectors have a shared effect in reducing days in which bacteria limits are exceeded. The difference between the baseline scenario and no collectors is also greater for bacteria than for suspended matter.

Contact: Ben Tomlinson,