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Typical Manning's n Values

Knowledge Base

Typical Manning's n values are available by right-clicking from within PC-Convey on certain screens (eg. the 'Create Cross-section' and 'Edit Multiple Manning's ns' screens).

While it is the responsibility of the User to determine appropriate Manning's n values, the following could be used as a guide:

Smooth concrete

0.013

Road (pavement only)

0.015

Side of house in flowpath

0.015

Rockwork - smooth

0.020

Earth channel - little or no grass

0.025

Road (if including footpath/nature strip)

0.025 - 0.035

Natural watercourse - 'less' vegetation

0.040 - 0.080

Natural watercourse - 'more' vegetation

0.090 - 0.150

Well-maintained grass / floodway

0.035

Rock - irregular

0.050

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