Run Scenario Simulations

Subtask Description:
Review and evaluate priority and feasibility of scenarios.

Action points of the implementation:
Developed scenarios must be reviewed to determine if they are feasible and prioritize which are most likely to be used. Once these have been selected they should be interpreted in the context of the model. That is, by determining how much to change forcing functions in the model to reflect these scenarios and to generate the data accordingly. This may require further data collection or inputs from external models.

Result: Identified scenarios to be applied to the simulation model which will represent the proposed management options.

Area:
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.

There are various possible combinations of management options for examining how the sewerage characteristics impact on bacteria. 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 here to demonstrate the output limits of the model.

Scenario 1 (baseline):
- 50% combined sewer outflow (CSO) directly released with storm water.
- Collector capacity of 0.52 GL. Note that 100% of CSO released directly is the same as zero storm water collector capacity.

Scenario 2 (no collectors):
- 100% of CSO released directly = 0 GL storm water collector capacity.

Scenario 3 (actual collectors; 25% direct):
- 25% CSO directly released with storm water.
- Collector capacity of 0.52 GL.

Scenario 4 (actual collectors; 0% direct):
- 0% CSO directly released with storm water.
- Collector capacity of 0.52 GL.

Scenario 5 (planned collectors; 50% direct):
- 50% CSO directly released with storm water.
- Collector capacity of 1.5 GL (planned).

Scenario 6 (planned collectors; 25% direct):
- 25% CSO directly released with storm water.
- Collector capacity of 1.5 GL (planned).

Scenario 7 (planned collectors; 0% direct):
- 0% CSO directly released with storm water.
- Collector capacity of 1.5 GL (planned).

 

These scenarios relate to public policy and describe a change in the management options and regulations.

Comments:
The adjustment of the structure implies additional testing of the revised model and re-assessment of its soundness. However, it is impossible to recalibrate or revalidate the adjusted model, because no data exist for the possible future situation characterised by the scenario.

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