SEAWAT/MODFLOW Model Instability After Adding High-Capacity Beach Wells

[MOHAMMED ALNAHHAL]

Hello everyone,

I built a SEAWAT/MODFLOW model and the model was running successfully with good calibration results. Everything was working correctly until I added three pumping wells representing the desalination plant beach wells.

These wells were set to start pumping after 1095 days. After adding them, the model only produced results for the periods before day 1095, and no results were generated afterward.

To investigate the issue, I created a separate model where the simulation starts directly with the operation of these pumping wells from day 0. However, the model completely collapsed and did not produce any results.

The beach wells pumping rate is 5280 m³/day per well, with screen elevations from -48 m to -79 m.

I would really appreciate any advice or suggestions from anyone who may have experience with similar SEAWAT/MODFLOW instability issues.

Thank you.

[Jakab Andras - Gmail]

If your simulation was steady-state, there is no effect in adding a well that would start pumping at a later time. For the second case, the model could colapse due to many reasons. First, make sure that your initial conditions are inherited from the results of the first simulation. If the problem still persists, check the lst file for reasons causing failure. 

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[Rahena Parvin Rannu]

Hi Mohammed,

What did it show while running? Not converged?

I am assuming that there may be high pumping issue that causes dry cell and then simulation didn’t converged or stopped. Check the pumping input if it correct. Also try with less pumping and see.

You can also play with changing initial time step, max time step size, number of inner and outer iteration etc and see how it goes.

As Jacob said, check lst file to see where it stopped and why.

Good luck.

Rahena 

To view this discussion visit https://groups.google.com/d/msgid/modflow/CAKmr6Mvp5EEfKX1XEv3g_VEid9giOS%3Dpc%2BJQicqMA8h%2BO67W7g%40mail.gmail.com.

[Enass Elimy]

you should check the pumping schedule regarding your data ,your schedule should appears as for example 

initial time	End time
0	1095
1095	7300

also you should check that your transient phase depending on the head data resulted from your steady state phase after calibration 

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