River Package Assigning Stage = 0 in Areas Where Polygon Partially Covers a Cell

[mgozdor]

I am using GMS 10.5 with MODFLOW USG.  I have a coverage that is using the river package.  The River is fairly wide so I created a polygon to represent the river.  To assign the stage I created a TIN with the transient stage data.  The problem is that when the polygon containing the river only partially covers a cell, GMS makes the cell a river boundary condition, assigns the bed elevation and conductance correctly, but assigns the river stage to be an elevation of zero feet.  This obviously causes a lot of errors.  Any solutions?

[Sean Czarniecki]

I've never assigned stage using a TIN, so I'm just guessing here.  It sounds like your polygon manages the bed elevation and conductance, so that is working properly.  However, when you use the TIN to assign transient stage data, does it only assign stage data where there are nodes?  If a node doesn't land in the partially covered cell, then stage data would remain zero.  Again, I'm just brainstorming.....

[mgozdor]

That ended up being the problem.  My TIN was created from the river coverage.  So if the TIN did not fully cover a cell where the river coverage assigned a river BC, then the stage would be assigned a zero value.  So, I had to make my transient TIN to overlap anywhere where the river coverage assigned a river BC before it would assign the proper stage.