Product(s):	CivilStorm, SewerGEMS, StormCAD
Version(s):	08.09.26.17 and later
Area:	Layout and Data Input

 

Problem

What is the purpose of the left and right overbank in the conduit properties, when using the "Bank Channel" roughness type of an irregular channel? What is the purpose of "left bank station"/"left overbank Manning's n", "right bank Station"/"right overbank Manning's n" and "channel manning's n"?

Solution

When selecting "Bank channel" as the roughness type of an irregular channel, the user must define the roughness coefficient for the left bank of the channel, right bank of the channel and central part of the channel. The "Left bank station" is the station point that marks the end of the left bank. The left bank is measured from the first station-depth point in the irregular channel section table to the selected point. The "left overbank Manning's n" is the roughness coefficient for the left river bank (the part of the channel to the left of the "left bank station".) The "right bank station" is the station point that marks the beginning of the right bank. The right bank is measured from the selected point to the last station-depth point in the irregular channel section table. The "right overbank Manning's n" is the roughness coefficient for the right river bank (the part of the channel to the right of the "right bank station".) The "channel Manning's n" is the roughness coefficient for the middle part of the channel, between the left and right bank stations. Basically if the water surface is below the banks, the "channel Manning's n" applies but if the flow rises to a point where some of it goes over the banks on the sides of the river, part of the flow is subjected to a different roughness, based on the coefficients entered.

You would also choose the Channel Weighting Method (default is Pavlovski) which is used to determine the overall Mannings n as water flows beyond the banks.

See Also

Original Author:

Jesse Dringoli