Conductance values for drains - Visual Modflow

[Julio Y.]

Hi all, 

does any know the exact formula used by Visual Modflow to calculate drain conductance (m^2/day) from values of linear conductance (1/day). Looks like it is the simple multiplication of linear conductance and cell area but I'm seeing different values when I convert the conceptual model to numerical model. 

Thanks in advance for any help!

Kind regards. 

Julio Y. 

[赵航剑]

Hi Julio,

I don't have lots of experience with Visual Modflow, but I did lots of gw modelling in GMS. In GMS, depending on the type of shapefile used to assign the DRN boundary, the value we put could be associated with different units.

For example: 

"when a conductance is entered for an arc, it should be entered in terms of conductance per unit length"

"For polygons, conductance should be entered in a conductance per unit area form"

https://www.xmswiki.com/wiki/GMS:Conductance

I am not sure whether this would be a similar case for this UI, and I would recommend to check the documentation as well.

Sounds like you got a linear conductance input, instead of using cell area, you might want to multiply the actual drain area within the cell area (e.g.wetland), unless the whole cell area is covered by a drain boundary.

Hope this helps,

Hangjian