HEC-RAS reads channel geometry from a text file composed of several sections. A discussion of the sections in the import file is provided below. And example RAS GIS import File is provided at the end of this appendix.

Header

The header is bounded by the records "BEGIN HEADER:" and "END HEADER:" and should contain a record to identify the units system used in the imported data set. The units system can be "US CUSTOMARY" or "METRIC". A summary of record that may be used in the Header section are provided in the table below.

Keyword

Value Type

Value

UNITS:

String

US CUSTOMARY or METRIC

DTM TYPE:

String

Type of terrain model (TIN or GRID)

DTM:

String

Name of terrain model

STREAM LAYER:

String

Name of Stream Centerline layer used in the CADD or GIS.

NUMBER OF REACHES:

Integer

Number of hydraulic reaches in the SDF file.

CROSS-SECTION LAYER:

String

Name of the Cross-Sectional Cut Lines layer used in the CADD or GIS.

NUMBER OF CROSS-SECTIONS:

Integer

Number of cross sections in the SDF file.

MAP PROJECTION:

String

Projection (coordinate) system used (e.g. Stateplane)

PROJECTION ZONE:

String

Projection zone (if applicable, e.g. 5101)

DATUM:

String

Reference datum for planar coordinates.

VERTICAL DATUM:

String

Reference datum for vertical coordinates.

BEGIN SPATIAL EXTENT:

None

None. Begin of Spatial Extents object.

Xmin:

Float

Minimum easting of geospatial data.

Ymin:

Float

Minimum northing of geospatial data.

Xmax:

Float

Maximum easting of geospatial data.

Ymax:

Float

Maximum northing of geospatial data.

END SPATIAL EXTENT:

None

None. End of Spatial Extents object.

NUMBER OF PROFILES:

Integer

Number of profile exported from HEC-RAS. RAS GIS Export File only.

PROFILE NAMES:

String array

Water surface profile names exported from HEC-RAS. RAS GIS Export File only.

River Network

The river network section is bounded by the records "BEGIN STREAM NETWORK:" and "END STREAM NETWORK:" and contains records describing reaches and reach endpoints. At a minimum, the stream network section must contain at least two endpoints and one reach.

A reach endpoint is represented by a record containing the keyword "ENDPOINT:" followed by four comma-delimited values containing the endpoint's X, Y, Z coordinates and an integer ID.

 A reach consists of a multi-record object that begins with a record containing only the keyword "REACH:" and ends with a record only containing the keyword "END:". At a minimum, a reach object must contain records setting values for a Stream ID, a Reach ID, a FROM point, and a TO point. A reach's FROM and TO point IDs must match IDs for endpoints listed before the reach object in the file. The reach object must also contain an array of locations defining the stream centerline. This array begins with a record containing only the keyword "CENTERLINE:" and ends when any keyword is encountered. A location element in the array contains the X, Y, and Z coordinates of a point on the stream centerline, and the point's river station. In HEC-RAS, elevation and stationing are optional in the stream network definition. If a location element includes a station value, it must occupy the fourth field in the element. If the elevation is not known, the word "NULL" must take its place.

Stationing is used for indexing locations along reaches, and is not used to precisely locate objects in the model. A summary of record that may be used in the River Network section are provided in the table below.

Keyword

Value Type

Value

ENDPOINT:

Location

X, Y, Z coordinates and integer ID.

REACH:

None

Marks beginning of Reach object.

END:

None

Marks end of Reach object.




The following records are required for a Reach object.



STREAM ID:

String

River identifier to include reach.

REACH ID:

String

Unique ID for reach within river.

FROM POINT:

String

Integer reference to upstream endpoint.

TO POINT:

String

Integer reference to downstream endpoint.

CENTERLINE:

Location array

Array elements contain coordinates and station values.

Cross Sections

The cross-sectional data section begins with a record containing the only the keyword "BEGIN CROSS-SECTIONS:" and ends with a record containing the only the keyword "END CROSS-SECTIONS:". A cross section is represented by multi-record object beginning with a record containing only the keyword "CROSS-SECTION:" and ending with a record containing only the keyword "END:."   A cross-sectional object must include records identifying the Stream ID, Reach ID, and Station value of the cross-section, a 2D cut line, and a series of 3D locations on the cross section. Stationing is given in miles for data sets with plane units of feet and in kilometers for data sets with plane units of meters. A cut line is composed of the label "CUT LINE:" followed by an array of 2D locations. A cross-sectional polyline consists of the label "SURFACE LINE:" plus 3D coordinates written as comma-delimited X, Y, Z real-number triples, one triple to a line. A summary of record that may be used in the River Network section are provided in the table below.

Keyword

Value Type

Value

CROSS-SECTION:

None

Marks beginning of Cross Section object.

END:

None

Marks end of a Cross Section object.




The following records are required for a Cross Section object.



STREAM ID:

String

Identifier for the River on which the cross section resides.

REACH ID:

String

Identifier for the Reach on which the cross section resides.

STATION:

Float

Relative position of the cross section on the river reach.

CUT LINE:

Location array

Array elements contain planar coordinates of cross section strike line.

SURFACE LINE:

Location array

Array elements contain 3D coordinates of cross section.




The following records are optional for a Cross Section object.



NODE NAME:

String

Description of cross section.

BANK POSITIONS:

Float

Fraction of length along cut line where main channel bank stations are located.(Left, Right)

REACH LENGTHS:

Float

Distance along left overbank, main channel and right overbank flow paths to next cross section downstream.(Left, Channel, Right)

N VALUES:

Float

Manning's n values expressed as a fraction along cut line to start of n value.(fraction, n value)

LEVEE POSITIONS:

String, Float

Levee positions expressed as a fraction along cut line to position with elevation.(ID, fraction, elevation)

INEFFECTIVE POSITIONS:

String, Float

Ineffective flow areas expressed as a fraction along cut line to beginning and end positions with trigger elevation.(ID, begin fraction, end fraction, elevation)

BLOCKED POSTITIONS:

Float

Blocked flow areas expressed as a fraction along cut line to beginning and end positions with trigger elevation.(ID, begin fraction, end fraction, elevation)

WATER ELEVATION:

String array

Water surface profile names exported from HEC-RAS. RAS GIS Export File only.


Additional Cross Section Properties

Geospatial data used for display purposes in HEC-RAS for levees, ineffective flow areas, are blocked obstructions are stored outside of the Cross Section block of information. A summary of additional cross section properties is summarized in the table below.

Keyword

Value Type

Value

Levee records



BEGIN LEVEES:

None

Marks beginning of Levees object.

LEVEE ID:

String

Levee identifier. Corresponds to ID in LEVEE POSITIONS object on cross section.

SURFACE LINE:

Location array

Array elements contain 3D coordinates of levee profile points. Array concludes with END:

END LEVEES:

None

Marks end of Levees object.




Ineffective flow area records



BEGIN INEFFECTIVE AREAS:

None

Marks beginning of Ineffective Areas object.

INEFFECTIVE ID:

String

Ineffective area identifier. Corresponds to ID in INEFFECTIVE POSITIONS object on cross section. Concludes with an "END:".

POLYGON:

Location array

Array elements contain 2D coordinates of ineffective area polygon points.

END INEFFECTIVE AREAS:

None

Marks end of Ineffective Areas object.




Blocked obstruction records



BEGIN BLOCKED AREAS:

None

Marks beginning Blocked Obstructions object.

BLOCKED ID:

String

Blocked obstructions identifier. Corresponds to ID in BLOCKED POSITIONS object on cross section.

POLYGON:

Location array

Array elements contain 2D coordinates of ineffective area polygon points.

END BLOCKED AREAS:

None

Marks end of Blocked Obstructions object.

Bridges / Culverts

The bridge/culvert data section begins with a record containing the only the keyword "BEGIN BRIDGE/CULVERTS:" and ends with a record containing the only the keyword "END BRIDGE/CULVERTS:". A bridge is represented by multi-record object beginning with a record containing only the keyword "BRIDGE/CULVERT:" and ending with a record containing only the keyword "END:."  Bridges/Culverts have the same required records as the Cross Sections object, but have other optional records. A summary of Bridge/Culvert records is provided in the table below.

Keyword

Value Type

Value

BRIDGE/CULVERT:

None

Marks beginning of Bridge/Culvert object.

END:

None

Marks end of a Bridge/Culvert object.




The following records are required for a Briodge/Culvert object.



STREAM ID:

String

Identifier for the River on which the bridge/culvert resides.

REACH ID:

String

Identifier for the Reach on which the bridge/culvert resides.

STATION:

Float

Relative position of the bridge on the river reach.

CUT LINE:

Location array

Array elements contain planar coordinates of bridge location.

SURFACE LINE:

Location array

Array elements contain 3D coordinates of bridge deck.




The following records are optional (but recommend) for a Bridge/Culvert object.



NODE NAME:

String

Description of cross section.

US DISTANCE:

Float

Distance to upstream cross section.

TOP WIDTH:

Float

Top width of bridge deck.

Inline Structures

The inline structures data section begins with a record containing the only the keyword "BEGIN INLINE STRUCTURES:" and ends with a record containing the only the keyword "END INLINE STRUCTURES:". An inline structure is represented by multi-record object beginning with a record containing only the keyword "INLINE STRUCTURES:" and ending with a record containing only the keyword "END:."  Inline structures have the same required records as the Bridge/Culvert object. A summary of Inline Structures records is provided in the table below.

Keyword

Value Type

Value

INLINE STRUCTURES:

None

Marks beginning of Inline Structure object.

END:

None

Marks end of a Inline Structure object.




The following records are required for a Inline Structure object.



STREAM ID:

String

Identifier for the River on which the inline structure resides.

REACH ID:

String

Identifier for the Reach on which the inline structure resides.

STATION:

Float

Relative position of the inline structure on the river reach.

CUT LINE:

Location array

Array elements contain planar coordinates of inline structure location.

SURFACE LINE:

Location array

Array elements contain 3D coordinates of inline weir profile.




The following records are optional (but recommend) for an Inline Structure object.



NODE NAME:

String

Description of inline structure.

US DISTANCE:

Float

Distance to upstream cross section.

TOP WIDTH:

Float

Top width of inline weir.

Lateral Structures

The inline structures data section begins with a record containing the only the keyword "BEGIN LATERAL STRUCTURES:" and ends with a record containing the only the keyword "END INLINE STRUCTURES:". A lateral structure is represented by multi-record object beginning with a record containing only the keyword "LATERAL STRUCTURES:" and ending with a record containing only the keyword "END:."  Lateral structures have the same required records as the inline structures object. A summary of Lateral Structures records is provided in the table below.

Keyword

Value Type

Value

LATERAL STRUCTURES:

None

Marks beginning of Lateral Structures object.

END:

None

Marks end of Lateral Structures object.




The following records are required for a Lateral Structure object.



STREAM ID:

String

Identifier for the River on which the lateral structure resides.

REACH ID:

String

Identifier for the Reach on which the lateral structure resides.

STATION:

Float

Relative position of the lateral structure on the river reach.

CUT LINE:

Location array

Array elements contain planar coordinates of lateral structure location.

SURFACE LINE:

Location array

Array elements contain 3D coordinates of weir profile.




The following records are optional (but recommend) for a Lateral Structure object.



NODE NAME:

String

Description of lateral structure.

US DISTANCE:

Float

Distance to upstream cross section.

TOP WIDTH:

Float

Top width of weir.

Storage Areas

The storage areas data section begins with a record containing the only the keyword "BEGIN STORAGE AREAS:" and ends with a record containing the only the keyword "END STORAGE STRUCTURES:". The keyword "SA ID:" identifies a storage area object. A summary of Lateral Structures records is provided in the table below.

Keyword

Value Type

Value

SA ID:

String

Storage area identifier.

POLYGON:

Location array

Array elements contain 2D coordinates of storage area boundary. Concludes with an "END:"

ELEVATION-VOLUME:

Float array

Elevation volume information for storage area. (Elevation, Volume)Concludes with an "END:"




The following records are optional for a Storage Area object.



TERRAIN:

Float array

X,Y,Z coordinates for terrain data within storage area. Concludes with an "END:".

Storage Area Connections

The storage areas data section begins with a record containing the only the keyword "BEGIN SA CONNECTIONS:" and ends with a record containing the only the keyword "END SA CONNECTIONS:". An inline structure is represented by multi-record object beginning with a record containing only the keyword "SA CONNECTION:" and ending with a record containing only the keyword "END:." A summary of Storage Area Connection records is provided in the table below. 

Keyword

Value Type

Value

SACONNID:

String

Storage area connection identifier.

USSA:

String

Identifier of upstream storage area (SA ID).

DSSA:

String

Identifier of downstream storage area (SA ID).

CUT LINE:

Location array

Array elements contain planar coordinates of storage area connection location.

SURFACE LINE:

Location array

Array elements contain 3D coordinates of weir profile.




The following records are optional for a Storage Area Connection object.



NODE NAME:

String

Description of storage area connection.

TOP WIDTH:

Float

Top width of weir.