Depth of Flow In an Open Channel (bioswale)

[Snydes]

This may have been covered before, but I was wondering if anyone has a straightforward method for calculating the depth of flow in an open channel (specifically bioswale). I have a design Q (flow), swale dimensions are T = 8, B = 2, side slopes 3:1, and slope is 1.5%.
Thanks.

 

[cvg]

mannings equation. google this site and you will find plenty of references to ways to calculate depth of flow in channels

 

[SMIAH]

FLOW PRO 2.1 is not bad for this
Freeware.