Manning's Equation Drainage Slope

Self-cleansing slope and slope to carry target flow at half-full.

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Formula and source

English Manning V = (1.486 / n) × R^(2/3) × S^(1/2), solved for self-cleansing slope at 2 ft/s and the slope to carry target flow at half-full with R = D / 4.

Manning equation; n-values from USGS WSP-2339 (public domain).

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