FLOOD01360

• County: Statewide
• Title: Hydraulic Design of Highway Culverts
• Date: 9/1/1998
• Prepared By: Federal Highway Administration
• Floodplain - Doc Type: Educational/Technical/Reference Information

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DEPTH OF FLOW WITHOUT -;M ::::J---

ADDEO DEPTH DUE TO BACKWATER

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CONTROl. SECllON

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4 SUBCRITICAL
FlOW
(lJ)W VEI..OCITYI
Frc I

Sl*ERCRlTICAL.
Fl.OW
(HIGH VE\..OCI'TY)
Fr.'
CRITICAL DEPTH

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Figure I-l2-Flow over a small dam (schematic).

Section

HW ...; Headwater
TW - Tailwater
W.S. - Water Surface
dc - Critical Depth

TW
W;!~_

XW.S.
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Figure I-13--Typlc:allnlet control flow condition,

b. Outlet Control. Outlet control
flow occurs when the culvert barrel is not
capable of conveying as much flow as the
inlet opening will accept. The control
section for outlet control flow in a
culvert is located at the barrel exit or

further downstream. Either subcritical
or pressure flow exists in the culvert
barrel under these conditions. Figure
1-14 shows two typical outlet control
flow conditions. All of the geometric
and hydraulic characteristigg of the

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