What is a Structure Inventory?

A structure inventory is a data set that consists of attributes of unique or groups of structures in the floodplain relevant to flood damage analysis.

What is the Purpose of a Structure Inventory?

A structure inventory is needed to calculate the consequences - in dollar-denominated terms - of flooding for the range of possible flood events.

Where Do I Get a Structure Inventory?

Modern approaches for putting together a structure inventory include the National Structure Inventory and/or the use of publicly-available data such as county tax records and Google Earth.

Below is an image of a structure inventory for Muncie, Indiana taken from the National Structure Inventory. The attributes of the structure, such as structure type and location, have been refined by reviewing Google Maps and Google Maps Street View imagery and editing the attribute table with geospatial software.

Working with Structure Inventories in HEC-FDA

HEC-FDA accepts point shapefile structure inventories only. The points in the shapefile represent the structure locations. Modifications to the structure inventory (e.g., to reflect non-structural actions) should be imported as distinct point shapefiles instead of the use of modules. The required attributes for each structure include:

  • Structure ID
  • Dollar-denominated structure value
  • Occupancy type
  • First-floor elevation or ground elevation and foundation height

Upon import, you need to select whether the first floor elevation or the ground elevation and foundation height will be used. If ground elevation and foundation height are selected, you will need to identify the source of ground elevation (structure inventory or terrain file). Optional attributes include:

  • Beginning damage depth
  • Content value
  • Other value
  • Year in service
  • Number of structures
  • Metadata/notes

Differences Between HEC-FDA Versions 1 and 2

  1. HEC-FDA Version 2.0 does not handle flat file structure inventories (i.e., tab-delimited text files). A structure inventory must be in the form of a point shapefile. 
  2. The structure inventory no longer requires information about stations because the software can read the data set to understand where the structures are located. This means that revising impact area delineations to match structural alternatives throughout plan formulation is clean and easy.  
  3. Structure modules will not be used in HEC-FDA Version 2.0. To reflect differences in structure inventories between project conditions or analysis years, import separate structure inventories. Only one structure inventory will be used for a given stage-damage compute, so each imported structure inventory should contain all structures required for a given project condition - analysis year combination. 
  4. Stage-direct damage functions were entered into study data as part of the structure inventory in HEC-FDA Versions 1. In HEC-FDA Versions 2, a stage-direct damage function is entered into study data as a manually-entered stage-damage function. 

Steps to Import a Structure Inventory

  1. Right click on Structure Inventories under Economics within the Study Tree and select Import from Shapefile.
  2. Give the imported inventory a useful name and description.
  3. Identify the path of the shapefile.
  4. Select first floor elevation or ground elevation and foundation height.
    1. If ground elevation and foundation height, select source of ground elevation.
  5. Identify required attributes and any optional attributes.
    HEC-FDA Version 2.0 Import Structure Inventory Importer Wizard Step 1 Example.
  6. Click next, select source of occupancy types, and match imported occupancy types to occupancy types in the structure inventory.
  7. Click Finish.
    HEC-FDA Version 2.0 Import Structure Inventory Importer Wizard Step 2 Example.