Multy-layer model, with aquifer, all dry

[sckara]

Good morning or evening,

i'm trying building a model with different layer (that I create from boreholes-> tin-> solid -> conceptual model), and under -40 meter from the surfaces i have an aquifer, Above and below the acquifer i have differt layer with different material.

In any case i create in MAP DATA: 1 coverage, with 2 no flux arcs, and 2 arcs defined as specific head ( i use the flow line of the piezometry for them), and some well.

1 coverage, with the poligon of source and sinks( rain and EV)

i create a modflow model, but i read different tutorial, and if i use as starting head the top elevation modflow give as reply only dry cell, but if i put as starting head the value of the piezometry, modflow don't work.

someone have some suggestion or idea?

thanks in advance for all the reply

sckara

ps. i'm using a modflow model 2005, package LPF, Solver PCG2

[Sean Czarniecki]

It sounds like your water table is below your top layer. Therefore, that layer should either be made an extension of the water table aquifer, or inactivated (there are things to also consider if you do that). By having a layer that totally dries out, MODFLOW will often run into solver problems. Unless you are going to allow it to rewet, it is usually best to eliminate having all of those dry cells.

[sckara]

thank you very much,

but now the simulation end with the error that the program is unable to read the file. hed, ( "file formatted incorrectly"), and that file.ccf stopped

i read this reply: http://forum.aquaveo.com/topic/1423-error-about-reading-some-file/

but even if i change the solver, i have the same problem. do you know why?

[Sean Czarniecki]

It sounds like the model still may not be converging. If the status box says that the model converged successfully, then there is still a mystery. If it didn't converge, GMS can't read a .hed file. You can look at the output file, go to the end and see if it says that it converged or didn't (and potentially figure out where in the model grid that there might be a problem). As the thread you linked suggested, run the model checker to see if there is anything obvious that is causing the problem.

[Jeremy Croes]

Hi,

I was running into a similar problem.

Setting starting heads of the entire grid to 0 helped the problem of the model resulting in dry cells.

Hope this helps.

Jeremy