Culvert Flow

Culverts are hydraulic structures to underpass embankments. The discharge through culverts (circular or rectangular) can be estimated following the framework described in Hager & Del Giudice (1998). It distinguishes between submerged - unsubmerged and inlet - outlet controlled devices.

(1) Unsubmerged inlet: h / D < 1.2

(1a) inlet controlled (critical flow): Qc = f (D, h, g)
(1b) outlet controlled (uniform flow): Qu = f (ce, D, dze, h, L, n)
Qculvert = min (Qc, Qu)

(2) Submerged inlet: h / D > 1.2

(2a) inlet controlled (gated flow): Qg = f (cd, D, h)
(2b) outlet controlled (pressurized flow): Qu = f (ce, D, dze, h, L, n)
Qculvert = min (Qg, Qu)

Equations:

Reference:
Hager W. H., Del Giudice G. 1998. Generalized Culvert Design Diagram. J. Irrig. and Drainage Engrgr. ASCE, Vol. 124 / 5.