Wetted perimeter

[1] The length of line of the intersection of channel wetted surface with a cross sectional plane normal to the flow direction.

The term wetted perimeter is common in civil engineering, environmental engineering, hydrology, geomorphology, and heat transfer applications; it is associated with the hydraulic diameter or hydraulic radius.

Engineers commonly cite the cross sectional area of a river.

The wetted perimeter can be defined mathematically as where li is the length of each surface in contact with the aqueous body.

In open channel flow, the wetted perimeter is defined as the surface of the channel bottom and sides in direct contact with the aqueous body.