I

U.S. Army Corps of Engineers,

Variables in the equation are defined in appendix

values of n by modifying the culvert length as

D.

directed in paragraph B6, which describes use

of the outlet-control nomography. The value of

Adding the three terms and simplifying, yields for

H must be measured from some "control" ele-

full pipe, outlet control flow the following expres-

vation at the outlet which is dependent on the

sion:

rate of discharge or the elevation of the water

surface of the tailwater. For simplicity, a value

hO is used as the distance in feet from the culvert

invert (flow line) at the outlet to the control el-

evation. The following equation is used to com-

This equation can be solved readily by the use

pute headwater in reference to the inlet invert:

of the full-flow nomography, figures BII through

B17. The equations shown on these nomo-

HW = hO + H LSO . . . . . . . . . . . . . . . . . . . . . . (2)

graphy are the same as equation 1 expressed in

a different form. Each nomograph is drawn for

a single value of n as noted in the respective

figure. These nomography may be used for other

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