Defining Culverts for HEC-HMS Storage Areas

The Culverts data panel of the Storage Area Data dialog box is enabled when Outflow Structures is selected as the routing method. Otherwise, this data panel entry is disabled (i.e., grayed out).
Culverts data panel of the Storage Area Data dialog box

The following sections describe how to interact with the Culverts data panel of the Storage Area Data dialog box.

Culvert Definition

In the Culvert Definition data table, the user can choose from different types of culvert shapes such as:

Box
Circular (default)
Semi-Circular
Ellipse
Arch
High-Profile Arch
Low-Profile Arch
Pipe Arch
CON/SPAN Arch

A maximum of 20 culvert structures can be defined, and each culvert structure can have 10 identical barrels. The user can also define the Flow Direction where the culvert flow is being routed. Main and Auxiliary are the available flow direction types.

Chart number
This dropdown combo box entry defines the Federal Highway Administration (FHWA) chart number of the culvert shape being defined. The chart number entry changes based upon the culvert shape selected.
Scale number
This dropdown combo box entry defines the FHWA scale number of the culvert shape being defined. The scale number entry changes based upon the chart number selected.
Solution criteria
This dropdown combo box entry defines the solution method to be used in the culvert computations. This dropdown combo box provides the following entries:
1. Automatic
2. Inlet Control
3. Outlet Control

Culvert Dimensions

This section contains the following options:

Diameter or height
This entry defines the diameter of a circular culvert or the height of the culvert shapes. This entry is disabled (i.e., grayed out) for the High-Profile Arch and Low-Profile Arch culvert shapes.
Width or span
This entry defines the width (or span) of the culvert shapes. This entry is disabled (i.e., grayed out) for the Circular, Pipe Arch, and Semi-Circular culvert shapes.
Culvert length
This entry defines the length of the culvert barrel. Clicking the […] button will cause the dialog box to temporarily disappear and allow the user to measure the length of the culvert barrel from the Map View.
Inlet invert elevation
This entry defines the culvert invert on the inlet (or upstream) side of the culvert.
Outlet invert elevation
This entry defines the culvert invert on the outlet (or downstream) side of the culvert.
Culvert slope
This read-only field automatically calculates the culvert slope.

Culvert Coefficients

This section contains the following options:

Entrance loss coefficient
This entry defines the entrance loss coefficient for the defined culvert. This coefficient describes the energy loss as water moves into the culvert inlet from the upstream area. Clicking the […] button displays the Culvert Entrance Loss Coefficients lookup dialog box.
Exit loss coefficient
This entry defines the exit loss coefficient for the defined culvert. This coefficient describes the energy loss as water moves from the culvert outlet to the downstream area. Clicking the […] button displays the Culvert Exit Loss Coefficients lookup dialog box.
Manning’s n
This entry defines the culvert Manning’s roughness coefficient. Clicking the […] button displays the Manning’s Roughness lookup dialog box.