Alternatives
What is an Alternative?
An alternative reflects a project condition and connects the results of two impact area scenarios for two analysis years and a given project condition.
What is the Purpose of an Alternative?
The purpose of an alternative is to collect the results necessary to compute equivalent annual damage (EqAD). Results include the distribution of equivalent annual damage (EqAD) results, EqAD results by damage category and by impact area.
Working with Alternatives in HEC-FDA
Differences Between HEC-FDA Versions 1 and 2
An alternative reflects the project condition dimension in HEC-FDA Version 2. An alternative is a new concept in the HEC-FDA software, though not a new concept in planning, and is closely associated with the Plan in HEC-FDA Version 1. For example, the without-project alternative reflects the information contained in the blue highlighted row in the image of the HEC-FDA Version 1 user interface below. The results of a given alternative are the same as computing equivalent annual damage analysis for a given plan in HEC-FDA Version 1. The discount rate and period of analysis are set in the study properties under the File menu. The discount rate should be provided in decimal form, not percentage.
Steps for Specifying Alternatives in HEC-FDA
To create a new alternative:
- First, set the study properties, including the discount rate and period of analysis. Open the Study Properties tab from the File menu.
- Enter the discount rate and period of analysis from the Properties dialog. Click Save and Close to close the dialog and set the discount rate and period of analysis.
Please note that the discount rate should be in decimal form, not percentage.
- Next, from the Study Tree, right-click on Alternatives and select Create New Alternative.
- Give the alternative a useful name (e.g., Without Project) and description.
- From the Base Year Scenario, select the appropriate created scenario (e.g., WOP_Base) and enter the correct base year (e.g., 2024).
- From the Future Year Scenario, select the appropriate corresponding future year scenario (e.g., WOP_Future) and enter the correct future year (e.g., 2054).
Note: you must be sure that the period of analysis in the Study Properties is consistent with the base and future years you select.
- Click, Save and Close.
- Either compute and view the alternative results, or continue creating additional project alternatives and view the summary results.
- To view the results for a specific alternative, from the Study Tree, right-click on the alternative and select View Results to compute.
- From the Alternative Results dialog, select the desired Report from the list which includes: Damage with Uncertainty, Damage by Impact Area, or Damage by Damage Category.
- Alternatively, compute and view the results summary table. To view the summary results, from the Study Tree, right-click on Alternatives and select View Alternative Summary Results.
- From the View Alternative Results dialog, select desired alternatives to include in the summary results, or click Select All and include all alternatives. Click View to open the summary results.
Review Alternative Results for more information.