Definition - What does Headwall mean?
A headwall is a wall, made of a variety of materials, often placed at the outfall of a drain or a culvert to serve as a retaining wall and protect fill from scour or undermining, increase hydraulic efficiency or divert the direction of flow. Headwalls are an important part of trenchless repair and rehabilitation efforts.
Trenchlesspedia explains Headwall
Headwalls are used to prevent the washing away of materials or undermining of the culvert's end. Headwalls can also be used to increase hydraulic efficiency in terms of the actual rate of flow through a culvert or change the direction of flow to help prevent infiltration and inflow. Used as a retaining wall at the end of a culvert, it can help to prevent loss of the earth around the end of the culvert by means other than scour or undermining.