Compare Peelvenen model MODLFLOW6 input with iMOD5

[JoerivanEngelen]

Compare Peelvenen model MODLFLOW6 & MetaSWAP input written by iMOD Python's from_imod5_data with iMOD5 RUNFILE batch option

[JoerivanEngelen]

Looking at the heads, there are two notable differences:

1. There is a large difference around the "Hoofdbreuk" HFB
2. There are differences around the edges of the model. Possibly related to the fact that iMOD5.6 doesn't place CHD cells, and the fact that we don't mask boundary condition cells where IBOUND==-1, see Mask topsystem packages where IBOUND == -1 #1787

I'll focus on what is causing the differences in HFB placement first, then I'll look at fluxes as well.

[JoerivanEngelen]

Apparently iMOD Python doesn't place HFB cells in layers 5, 12, and 16 for the main fault. I'll have to investigate why that is the case. Also haven't looked at the hydraulic_characteristic/resistance yet:

[JoerivanEngelen]

The differences are probably explained by the known issue of iMOD5, where it incorrectly computes resistances: It effectively adds a background resistance (the resistance of the horizontal conductivities) twice if you use a positive multiplication factor. I tested the workaround in the documentation (setting the multiplication factor to a negative value), but this generates an empty file, so it is hard to run a proper comparison with the HFB package.