Importing HEC-RAS Geometry Files

The following objects can be imported from HEC-RAS geometry files:

HEC-RAS Object	InfoWorks ICM Object
River Reach	River Reach
Cross Sections / Interpolated Cross Sections	Cross Section Line
Bridge	Bridge Link and Cross Section Lines
Storage Area	Storage Area and associated Storage Node
Lateral Structure	Bank Line
Storage Area (2D)	2D Zones
Land Cover (LC) Regions	Roughness Zones
BC Lines	2D Boundaries
Break Lines	General Lines
Connections	Base Linear Structures

The Import Process

To import network data from HEC-RAS files:

Open the network to be updated
Select Import | Model | from HEC-RAS network data from the Network menu. This displays a standard Windows File Open dialog
Select the .prj file to be imported and click Open (the .prj file is read to determine which units the HEC-RAS data is defined in)
Select the geometry file to be imported and click Open

For details of the objects imported and conversions made by the importer, see the Conversion Notes below.

Note

InfoWorks ICM can only import objects to the correct location if georeferencing information is available in the HEC-RAS geometry file

Conversion Notes

River Reach Objects

HEC-RAS River Reach objects are imported as InfoWorks ICM River Reach links:

Break nodes are generated at upstream and downstream ends of the river reach, with node ID generated from the HEC-RAS reach name.
The river reach link is split at bridge locations and break nodes generated upstream and downstream of the bridge, with node ID generated from the HEC-RAS cross section ID upstream / downstream of the bridge.

Cross Sections / Interpolated Cross Sections

HEC-RAS Cross Sections and Interpolated Cross Sections are imported as InfoWorks ICM Cross Section Lines. River reaches can be built from the imported river reach links and cross section lines after the import process has been carried out.

The cross section line ID is generated from the HEC-RAS cross section ID.

ICM Cross Section Line Data	Import Notes
X and Y	Calculated from intersection of HEC-RAS cross section with river reach.
Bed level	Imported from HEC-RAS Elevation data Obstructions Where obstructed areas are defined, Elevation will be set to the obstructed area elevations defined in HEC-RAS: For normal obstructed areas, Elevation will be set to the HEC-RAS obstructed area values at all points to the left of the defined station and to the right of the defined right station. For blocked obstructed areas, Elevation will be set to the HEC-RAS obstructed area elevation values between the defined pairs of left and right stations.
Roughness Manning's n	Imported from HEC-RAS n Val data Ineffective flow areas Where ineffective flow areas are defined, Manning's n will be set to 0: For normal ineffective areas, Manning's n will be set to 0 at all points to the left of the defined left station and to the right of the defined right station. For blocked ineffective flow areas, Manning's n will be set to 0 between the defined pairs of left and right stations. Note InfoWorks does not support non-permanent ineffective flow areas. Non-permanent ineffective flow areas will be treated as permanent ineffective flow areas.
New panel	Set at changes in Manning's n

Bridges

HEC-RAS Bridges are imported as an InfoWorks ICM bridge link and cross section lines representing bridge upstream, downstream and deck sections:

As HEC RAS has no geoplan geometry for the bridge deck, the cross section line representing the bridge deck is created by inserting an interpolated section and then populating the elevation data from bridge deck data.
The bridge deck is represented by one section in InfoWorks ICM, but by two in HEC RAS. Only the upstream deck data from HEC RAS is imported into ICM.

Bridges can be built from the imported bridge links and cross section lines after the import process has been carried out.

Note: the import of bridge opening data is not currently supported.

Storage Areas

HEC-RAS Storage Areas are imported as InfoWorks ICM Storage Areas and associated Storage Nodes.

The storage area and storage node IDs are generated from the HEC-RAS storage area name
Storage area and storage node X and Y coordinates are imported from the HEC-RAS storage area
The Level-Area grid of the node's storage array is populated with values from the HEC-RAS storage area:
- If the Area x Depth method has been used, one level / area pair is imported into the grid from the HEC-RAS Area and Min Elev. fields. A second level / area pair is added to the grid assuming a constant area.
- If the Elevation versus Volume Curve method has been used, pairs of level / area values are imported from the HEC-RAS Elevation Volume Curve.

Lateral Structures

HEC-RAS Lateral Structure objects that are attached to river sections are imported as InfoWorks ICM Bank Lines.

ICM Bank Line Data	Import Notes
X and Y	Imported from HEC-RAS X,Y data
Bank level	Imported from HEC-RAS Elevation data
Discharge coeff - cd	Imported from HEC-RAS Weir Coefficient data
Modular limit	Not imported

Storage Areas (2D)

HEC-RAS Storage Area objects with 2D flags are imported as InfoWorks ICM 2D Zones. Basic geometry is imported.

Land Cover Regions

HEC-RAS Land Cover (LC) Region objects are imported as InfoWorks ICM Roughness Zones. Basic geometry is imported. Roughness is not imported as the mechanisms for determining it is significantly different between HEC-RAS and InfoWorks ICM.