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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