💧 IGW-NET · Quick Tutorial 2 of 31

Tutorial 2: Nested Modeling

Create a detailed sub-model embedded within a regional model. Interpolate boundary conditions from the parent model to the nested domain.

IGW-NET Tutorial 2 Prereq: MAGNET4WATER account 2 sections

This tutorial covers

  1. Creating a Nested Model at Fort Custer, MI
  2. What's Next

1Creating a Nested Model at Fort Custer, MI

Step 1 — Load the Parent Model

Click Load Model button to load the parent model domain using a previously saved model file from Tutorial 1 (Steady 2D Flow Modeling). Submit the parent model for simulation to generate the regional flow solution that will provide boundary conditions for the child model.

Step 2 — Delineate the Submodel Domain

Click Draw Domain button to delineate the submodel domain within the parent model results. Draw a box around your area of interest — in this case, Fort Custer, Michigan. The submodel domain must be entirely contained within the parent model.

Step 3 — Inherit Boundary Conditions from Parent

Click Settings button to open the Default Model Input Parameters and Display Options window. Check the 'Boundary Condition from Parent model' option box. This tells the child model to extract its boundary conditions directly from the parent model's computed solution — no manual boundary setup needed.

Step 4 — Submit and Simulate

Click Submit button to submit the new submodel for simulation. The child model runs at higher resolution within the boundary conditions inherited from the parent. Results show finer detail in the area of interest while maintaining consistency with the regional flow pattern.

Step 5 — Repeat: Nest Deeper

Continue to repeat Steps 1–4 until the area of interest is captured in sufficient detail. Each nesting level zooms in further: regional → subregional → local → site. At each level, the parent's solution feeds the child's boundaries automatically.

Step 6 — Save or Publish

Click Save button Publish button to save or publish the final submodel for future use.

Complete nested modeling workflow showing parent model with regional head contours on left, submodel domain drawn inside the parent on upper right, and the nested model results at higher resolution on lower right — boundary conditions inherited from parent solution
Figure 1–2: Nesting a submodel within the parent model. Left: parent model with regional flow. Right: submodel domain drawn inside the parent, inheriting boundary conditions. The child model resolves finer detail while maintaining consistency with the regional solution.
Progressive nesting from regional to local scale showing three zoom levels — each inheriting boundary conditions from its parent, with increasing grid resolution at each level
Figure 3: Progressive nesting — regional → subregional → local. Each level increases resolution and detail. The modeling hierarchy becomes the management hierarchy.

Key Concepts

Grid-independent conceptual model: Wells, rivers, boundaries, and geological features are defined as real-world xyz objects. When you create a child model at finer resolution, these features auto-remap to the new grid — you don't rebuild anything.

No artificial boundary effects: By starting with a regional model much larger than the area of interest, the outer no-flow boundaries have negligible impact on the nested results. Each child model inherits physically meaningful boundary conditions.

Incremental refinement: You don't need to decide the final resolution upfront. Start coarse, identify where detail matters, nest there. Add more levels only where the science demands it.

2What's Next

With nested modeling mastered, continue the learning path:

Tutorial 3: Particle Tracking — trace flow paths and delineate wellhead protection areas within your nested models
Tutorial 4: Water Balance — analyze inflows, outflows, and storage at any nesting level
Tutorial 5: Contaminant Transport — simulate plume migration at the site scale using nested resolution