Wetland CN

[watershedc]

Hello,

Does anyone have a suggestion on appropriate CN to use for multiple wetland areas, which are included in a large scale modeling analysis? The wetland areas appear to hold permanent pools of water based on orthophotography, although I'm hesitant to assign a high CN such as 98 or even 100 given the likelyhood the wetlands have significant storage capacitities above the water surfaces. Obviously many complex processes going on in each area but I'm just trying to get a decent estimate, given the scale of the analysis. Thanks.

 

[psmart]

The "storage capacities above the water surface" would generally be modeled by using a pond or reach routing. This would allow for the delay is water leaving the wetland. A CN value of 98-100 is appropriate for your "runoff" calculation. Anything lower will cause losses (infiltration) that does not exist in this situation.


Peter Smart
HydroCAD Software

http://www.hydrocad.net