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Gutter & Inlet Capacity

Compute gutter flow Q from spread T and slopes (HEC-22), then curb-opening intercept length LT and inlet efficiency E.

Inputs

Spread T (m)

Cross slope Sx

Long. slope SL

Manning's n

Inlet length L (m)

Inlet width W (m)

Method — HEC-22

Gutter Q = (0.376/n)·Sx^(5/3)·SL^(0.5)·T^(8/3) [SI].
Curb-opening LT = 0.817·Q^0.42·SL^0.3·(1/(n·Sx))^0.6 (full interception).
Efficiency E = 1 − (1 − L/LT)^1.8 for partial L.

Results

Gutter Q—

LT (full intercept)—

Efficiency E—

Intercepted Qi—

Bypass Qb—