HEC-FIA and Flood Damages Reduced in CWMS

Workshop Data

Project Files

Download the Initial Project Files here. Unzip in the C:\CWMS_Class directory. CWMS 3.5 was used to create the workshop files and instructions.

Background

In this workshop, you will be introduced to HEC-FIA in CWMS and the process of reviewing flood inundation damages from CAVI forecast simulations. This workshop will also introduce a Flood Damages Reduced Simulation.

There are two HEC-FIA alternatives set up in this workshop. The first is for a single event. The second is for a Flood Damages Reduced simulation.

The first HEC-FIA model has been set up to read gridded results and stage hydrographs at some specific cross-section locations from HEC-RAS. The gridded results consist of maximum depth. HEC-FIA uses this information to compute structure damage. The hydrograph output from cross-sections allows HEC-FIA to establish the timing for issuance of flood warnings. It also allows HEC-FIA to determine when the flood levels at certain river locations cross key thresholds for impact response.

This HEC-FIA model has been set up to compute structure and content damages in terms of dollar losses. Additionally, the compute has been set up to track when critical infrastructure elements have been flooded. Finally, the model has impact response curves set up at the Hopland, Healdsburg, and Guerneville (Johnson's Beach) gages to track the exceedance of flood stage. All of these computes are based on the hydraulics from HEC-RAS.

The structure inventory for computing flood damages to structures in the HEC-FIA model was developed from a shapefile with parcel-level detail. It has been quality-controlled, and modelers should review the consequence results and exercise judgment in their interpretation. It is representative of what consequences are available in the floodplain but needs to be properly reviewed before being truly representative of the damages for an event. This advice applies even more strongly in watersheds where the structure inventory derives from more generalized data sources.

The second HEC-FIA alternative and CWMS Forecast calculates the Flood Damages Reduced for the Jan 2017 event. Two separate HEC-RAS simulations are computed, with the second HEC-RAS simulation representing the "Without Project" or "Unregulated" conditions in the watershed. HEC-FIA then calculates the difference in damages between the two events and provides an estimate of Flood Damages Reduced. More information can be found in the USACE Annual Flood Damages Reduce SOP here: https://www.hec.usace.army.mil/confluence/cwmsdocs/AFDR/latest. 

The data sources are listed below, and are common for HEC-FIA models:

• For the Counties and State Shapefiles the HAZUS database was used.
• For the structure inventory, a point shapefile from local government was used.
• For the Critical Infrastructure, a modified version of the HSIP-GOLD database was used.
• For the Impact response curve information the following three gage locations were used:
  • http://water.weather.gov/ahps2/hydrograph.php?wfo=eka&gage=HOPC1
  • http://water.weather.gov/ahps2/hydrograph.php?wfo=eka&gage=HEAC1
  • http://water.weather.gov/ahps2/hydrograph.php?wfo=eka&gage=GUEC1

Objective

The objective of this workshop is to familiarize you with the Hydrologic Engineering Center's Flood Impact Analysis (HEC-FIA) software. In this workshop you will open an existing HEC-FIA model, compute the forecast, and review some reports.

The workshop consists of a series of tasks which will result in a single run of the HEC-FIA consequences calculations. Following that, you will review results, and attempt to make a few adjustments to the inventory data if necessary.

Tasks

Task 1: Open a Watershed and Real-time Real-time Forecast

Task 2: Viewing HEC-FIA Inputs

Task 3: Reviewing HEC-FIA Results

Task 4: Reviewing Flood Damages Reduced Forecast

Solution Files

Project Files

Download the Solution Data here if you would like the watershed and forecast with the full solution.