I am currently trying to build a model in MODFLOW-USG similiar to a model in MODFLOW-NWT. My NWT model is fast and robust.
I have tried to build a similar model of the same area in USG in different ways, ending with the same problem. The model will not converge if any cells is dry. I discovered this by adjusting the recharge parameter. My USG model converged when the recharge was extremely high and no cells were dry.
I tried to "convert model to MODFLOW-USG simulation" in GMS to check if the model would converge when there was no difference in grid structure. I get the same result. I need to increase the recharge to have no dry cells and a model that does not crashes.
Can anyone tell me if the SMS solver in MODFLOW-USG can be set up in the same way as the NWT solver to handle dry cells, and how?