A compliant RAS2FIM HEC-RAS model

Goals:

• To visually outline what a “compliant” model

Outcomes and Takeaways:

• A better understanding of what sort of HEC-RAS model RAS2FIM was developed against
• The ability to predict (at a gross level) whether a given HEC-RAS model is or is not expected to run
• These HEC-RAS models are largely representative of the BLE standard, at least as implemented across FEMA region 6

RAS2FIM timeline

Review: A Modern HEC-RAS

USACE History

• first engineer officers of the Army on June 16, 1775
• permanent branch on March 16, 1802

HEC History

• HEC-2: WIZ by Bill S. Eichert in 1964. This early version was developed on a GE 225 system at the Corps of Engineers Tulsa District office. In 1966 the first FORTRAN version of HEC-2 was released by the Hydrologic Engineering Center (HEC) under the name “Backwater Any Cross Section.”
• 1995: first GUI software
• Now we’re here (V4 included enhancements for visualization, unsteady flow, and sediment transport)

St Louis Dredge potter (1932)

Review: The First 2D HEC-RAS

HEC2

Review: HEC-RAS 2025

HEC-alpha

RAS2FIM workflow

HEC-RAS data format

Example model 1

The sample Iowa Flood Center HEC-RAS model

Models:

• 1D, 1 reach - nothing fancy
• (2D/Storage)
• Active plan points to flows

Stations: Can be a-spatial or have mismatched projections/datums Do not have to start at 0 Do not have to add up to the geometric/geographic length of the cross section

Example model 2

Model sources

A screenshot of the FEMA region 6 BLE dashboard

Thinking about how you would scale this out? There are a few different technical hurdles to look out for, see the need for a more FAIR HEC-RAS format here.

What’s next?

Outcomes and Takeaways:

• A better understanding of what sort of HEC-RAS model RAS2FIM was developed against
• The ability to predict (at a gross level) whether a given HEC-RAS model is or is not expected to run
• These HEC-RAS models are largely representative of the BLE standard, at least as implemented across FEMA region 6

Next Steps:

• Gather HEC-RAS models - particularly Base Level Engineering models.
• Set up unit tests - see the unit test docs.
• Solve Hydrology.

This presentation (placeholder)

Sources: