Slope-Area Method (SI) for Discharge

from "Chow, V.T., Maidment, D.R., Mays, L.W., 1988, Applied Hydrology: New York, McGraw- Hill."

Manning's n Tables Manning's n values for Channels, Closed Conduits Flowing Partially Full, and Corrugated Metal Pipes.

Manning's n Table TxDOT Manning's n Table

Estimates discharge in US customary units from

Q = (1.0/n)*A*(A/P)^(2/3)*S^(1/2)
    Q is the discharge (cubic meters per second)
    n is Manning's roughness coefficient (read from table)
    A is cross sectional flow area (square meters)
    P is wetted perimeter (meters)
    S is friction slope (often the channel slope is substituted)

----- INPUT VALUES -----

Manning's n Look-Up
Flow Area (m^2)
Perimeter (m)
Slope (m/m)