LPF package convertible upstream option

[Laura Rod]

Hello

My model is not running when I set the 1st layer as convertible (Unconfined aquifer). However, when I tested the Convertible Upstream option in the LPF package my model finally ran (still didn't converge tough). In what cases do you recommend to use the Convertible Upstream option from the LPF package? I'd like to know if it is recommended for a 2-layer unconfined aquifer before changing other parameters in my model to make it converge.

[HelenaH]

Hi Laura,

If it's just a simple 2-layer model, you should be able to use convertible layers, even before changing your parameters. However, I've experienced issues with using convertible layers if the layers are too thin, and/or if there are dry cells. Though I've only had this issue with ugrid (unstructured grid) models it might also occur using a structured grid. 

All in all, there should be no issues using the LPF package and convertible layers, however there might be other issues with the model resulting in MODFLOW ending before running the model. 

[Laura Rod]

On 9/17/2022 at 3:52 AM, HelenaH said:

Hi Laura,

If it's just a simple 2-layer model, you should be able to use convertible layers, even before changing your parameters. However, I've experienced issues with using convertible layers if the layers are too thin, and/or if there are dry cells. Though I've only had this issue with ugrid (unstructured grid) models it might also occur using a structured grid. 

All in all, there should be no issues using the LPF package and convertible layers, however there might be other issues with the model resulting in MODFLOW ending before running the model. 

Thanks HelenaH. My model has a Ugrid as well. I ran the model with convertible negative and now I'm running it again with convertible layer and it takes longer, the convertible upstream option is much faster. I am waiting for the results of this second run to see if it makes any difference on my heads.