What is a scenario?

A scenario collects the hydrologic, hydraulic, and economic data for each impact area and for a given project condition and analysis year.

What is the purpose of a scenario?

A scenario consists of the set of summary relationships that are sampled during the Monte Carlo simulation. The scenario Monte Carlo simulation provides expected annual damage and project performance results for each impact area. Expected annual damage results include the distribution of expected annual damage and expected annual damage by damage category. Project performance results include the distribution of AEP, long-term exceedance probability, and assurance of the target threshold.

Working with scenarios in HEC-FDA

Differences Between HEC-FDA Versions 1 and 2

A scenario is a new concept to the HEC-FDA software. A scenario reflects study configuration at the plan-analysis year level. This concept explicitly allows for a more nimble configuration through the ability to assign any of the input functions/data to a given plan-analysis year combination. A scenario contains the same information/configurations contained by the blue highlighted row in the image of the HEC-FDA Version 1 interface below. The default threshold in HEC-FDA Version 2 is calculated in the same the way that the default threshold is calculated in HEC-FDA Version 1. Expected annual damage and project performance results of a scenario are the same results obtained from evaluation of plans by analysis year for a given plan-year combination (a given row in the image below) in HEC-FDA Version 1. 

Steps for Configuring a Scenario in HEC-FDA

  1. Right-click on Scenarios and select Create New Scenario
  2. Give the scenario a useful name, description, and specify the analysis year
  3. For each impact area, select:
    1. Frequency function
      1. If using flow-frequency, specify rating curve
    2. Set of aggregated stage-damage functions
  4. Optionally, select:
    1. Regulated-unregulated 
    2. Lateral structure (levee)
    3. Exterior-interior
  5. Optionally, add custom thresholds
  6. Hit preview compute to view damage frequency function and deterministic calculations of EAD and AEP, and close.
  7. Right-click on the scenario within the Study Tree and select Compute
  8. Right-click on the scenario within the Study Tree and select View Results
  9. Select the type of report - Expected Annual Damage or Project Performance, and select result of interest. See Scenario Results for more information. See below for finished Scenario setup and results.

Optionally, users can compute multiple scenarios at once by right-clicking on Scenarios and selecting Compute Scenarios... Check the boxes for the scenarios of choice and click Compute. See the images below.