1Pseudo-3D Model — Fort Custer, Michigan
Step 1 — Load and Simulate the 2D Parent Model
Click 
to load the regional model from Tutorial 1, then add a submodel and apply 'Boundary Conditions from Parent Model' in the Default Attributes menu.
Step 2 — Simulate the 2D Submodel First
Click 
to submit the 2D submodel for simulation. This produces the water table solution that will define the top of the pseudo-3D model in the next steps.
Step 3 — Save the Model and Configure Sublayers
Click 
to save the 'Latest Model Zipped File'. Then open the Simulation Settings tab in the Default Model Input Parameters and Display Options menu. Check the box next to 'SubLayers=' and specify the number of vertical computational layers — for example, 5 sublayers divides the aquifer thickness into 5 equal vertical slices.
Step 4 — Apply "Water Table as Top"
Click 
and check the box next to 'Water Table as Top'. This tells the model to use the computed water table (from Step 2) as the top elevation of the pseudo-3D model — instead of the land surface. The aquifer is now bounded by the water table above and the aquifer bottom below, subdivided into the number of sublayers you specified. Then apply 'Boundary Conditions from Parent Model', check 'Import', and upload the zipped file from Step 3.
Step 5 — Draw a Cross-Section
Click to draw a cross-section through an area of interest. This cross-section will now show multiple computational layers — revealing vertical flow structure that was invisible in the 2D model.
Step 6 — Re-Submit for Simulation
Submit the pseudo-3D model for simulation. The solver now computes flow in each sublayer independently — horizontal AND vertical flow components. Vertical circulation patterns emerge: downward flow in recharge areas, upward flow near discharge features (rivers, drains).
Step 7 — View Cross-Section and 3D Results
Click 
the 'Analysis' button, then select 
'Display Charts'. This launches analysis windows including the full cross-section chart (showing vertical flow vectors and head distribution across layers) and the 3D forms chart (showing the aquifer structure and flow in three dimensions).
Step 8 — Save or Publish
Click 
to save or publish the model for future use.
Key Concepts
"Water Table as Top" — why it matters: In a 2D model, the top elevation is typically the land surface (DEM). But between the land surface and the water table, there's an unsaturated zone where groundwater equations don't apply. By using the water table as the model top, the pseudo-3D model represents only the saturated aquifer — making the sublayer computation physically correct. The water table is smoother than the DEM, which also improves numerical stability.
Sublayers vs aquifer layers: Sublayers are purely computational — they divide a single aquifer unit into vertical slices of equal thickness. Aquifer layers (Tutorial 10) represent real geological units with distinct properties. You can have sublayers WITHIN an aquifer layer for even finer vertical resolution.
When to use vertical resolution: Add sublayers when you need to see vertical flow patterns (recharge/discharge dynamics), model contaminant plume depth, track vertical migration of DNAPL or LNAPL, or resolve flow near partially penetrating wells. If your questions are purely about horizontal flow patterns, 2D is sufficient and faster.
2What's Next
With vertical dynamics captured, continue the learning path:
Tutorial 7: Transient Modeling — add time-varying conditions to see how vertical flow patterns respond to seasonal pumping and recharge
Tutorial 10: Aquifer Layers — add entirely new geological layers with distinct properties (the full 3D approach)
Tutorial 8: Calibration — match your multi-layer model to observed heads at different depths