Headwall

This is a structure that forms an entrance to an underground pipe or culvert. Usually, it is a wall built around the upper end of the conduit with side walls or wingwalls that guide flows into the conduit.

In DRAINS, headwalls are used  where an open channel enters a pipe or set of pipes, and overflows may occur over the top of the headwall. 

If water rises above the nominated overflow level for the headwall, the headwater level will be set by weir characteristics or an elevation-discharge relationship defined in the property sheet for the overflow route leading out of the headwall.

The DRAINS headwall should only be located at the entrance to a pipe.  In engineering practice, the term 'headwall' is sometimes applied to the outlet of a pipe where flow discharges into an open channel or waterbody, or 'tails out' flows, spreading them over an area of land.  In DRAINS an outlet of this kind must be modelled as a node, as shown below:

• Related Articles

• Headwall drawing tool

  This tool, , allows you to draw a headwall in the Main Window. When you click on this tool, the arrow cursor changes to a pencil. Click the cursor on the point where the headwall is to be inserted, and the headwall symbol will occur. To enter data, ...

• Headwall property sheet

  Headwalls can be used in cases where an open channel enters a pipe and overflows can occur over the top of the headwall. The inputs to the property sheet for a headwall consist of its name (of up to 10 characters), an entrance loss factor and an ...

• Overflow route from a detention basin or headwall

  For this situation, the Overflow Route property sheet must contain the required information for an overflow route from a pit, plus information about the high-level outlet of the basin or the surface overflow from the headwall. This can be in the form ...

• Culvert property sheet (obsolete)

  This window displays the information for a culvert specified as a single object , a form that is now obsolete and not available for new DRAINS projects. For these, enter a headwall, pipe, overflow route and node, as shown below. In the property sheet ...

• Culverts

  This refers to a system involving a headwall, pipes and an outlet that is used to convey water under earthworks or structures that fill a waterway, such as a road embankment. The headwall on the upstream side of the culvert usually has side walls or ...