Tutorial 23: MODFLOW Analysis Tool

1Load and Inspect

Step 1 — Load and Simulate the Model

First, ensure the unstructured grid model from Tutorial 21 is available. Load it via 'Other Tools' → 'LoadModel' → 'Local Model File' (or 'Last Model on Server'). Run the simulation: 'Simulation Tools' → 'Simulate'. The parent model results appear in the map display.

Step 1 — Unstructured grid model loaded and simulated — parent model results displayed

Step 2 — Open the MODFLOW Analysis Tool

Go to 'Other Tools' → 'LoadModel' → 'ModFlow Model'. This opens the MODFLOW from ZipFile interface. Select 'Last magnetMF Model' to load the model you just simulated. This loads the MODFLOW model files — grid definition, boundary conditions, properties, and solver settings — into the analysis environment.

Step 2a — MODFLOW from ZipFile interface with Last magnetMF Model option selected

Step 3 — Inspect Boundary Conditions

Click 'Boundary Conditions' in the ZipMODFLOW interface. A new display opens showing the model grid with inactive cells highlighted by default. Check the boxes next to 'WEL' and 'RIV', then click 'Update Display'. The display now highlights which cells contain well packages and river packages — you can see exactly where boundary conditions are assigned without opening any input files.

Step 2d — Boundary conditions displayed: WEL and RIV cells highlighted on the unstructured grid

Why Inspect Before You Run?

Trust but verify: Before running any model, you should confirm that boundary conditions are where you expect them. Are the river cells along the actual stream? Are the well cells in the right locations? Are there inactive cells that shouldn't be? The boundary condition display gives you instant visual QA — catching errors that would otherwise produce puzzling results.

Applicable to any MODFLOW model: This inspection capability works for any MODFLOW model you load — not just ones built in IGW-NET. If you receive a model from a colleague, a regulatory agency, or a legacy archive, the first thing you should do is inspect its boundary conditions. The MODFLOW Analysis Tool makes this a one-click operation.

2Add Basemap and Run

Step 4 — Capture a Terrain Basemap

Click 'Display Options' in the Boundary Conditions interface. Navigate to the 'Basemap Display' tab. Click 'Capture Basemap' to capture the TERRAIN map within the model area. Check 'Show basemap' and click 'Update Basemap'. The terrain imagery now serves as the background for all subsequent results — giving spatial context to every head contour and flow vector.

Step 3a — Display Options interface for configuring basemap and model display settings

Step 5 — Run and Display Results on Terrain

Close the Display Options and Boundary Conditions interfaces. In the ZipMODFLOW interface, click 'Run Model'. After the simulation completes, the MODFLOW Results interface opens with head contours and velocity vectors overlaid on the terrain basemap. This is the power of the tool — MODFLOW results in geographic context, not just abstract colored cells.

Step 3f — Simulated head contours and velocity vectors overlaid on TERRAIN basemap

Step 6 — Zoom Into Areas of Interest

Click 'Display Options' in the MODFLOW Results interface. Click 'draw rectangle', then draw a zoom box on the map display (two clicks define opposing corners). Click 'Save', then 'Update Display'. The display refreshes to show the zoomed area — detailed head contours and flow vectors at higher visual resolution. This interactive zoom lets you examine any part of the model without changing the grid or rerunning.

Step 4 — Zoomed into area of interest showing detailed head contours and flow patterns

Step 7 — Reset to Full Model View

To return to the full domain: click 'Display Options', go to the 'Model Display' tab, click 'clear' to remove the zoom window, then 'Save' and 'Update Display'. The display returns to the complete model extent.

3Particle Tracking with MODPATH

MODPATH Inside the Analysis Tool

Seamless integration: Traditional MODPATH workflows require exporting MODFLOW results, creating separate MODPATH input files, running MODPATH externally, and importing pathline files back into a visualization tool. The MODFLOW Analysis Tool eliminates all of this — click 'Pathlines', define particle release locations interactively on the map, and run MODPATH directly. Results display immediately in the same interface.

Flexible particle release: Particles can be released in multiple ways: around a well or point (with configurable radius), within a zone, along a line, from model features, or from an uploaded file of starting positions. This tutorial demonstrates the point-release method — placing particles around the injection well to trace where injected water goes.

Step 8 — Set Up MODPATH Particle Tracking

In the MODFLOW Results interface, click 'Pathlines'. This opens the Create MODPATH Model interface. Configure:

1. Check 'Release from around well/point'
2. Set Particle Well Radius to 50 meters
3. Click 'Add Well' then click on the map at the injection well location
4. Click 'Save'

Default simulation parameters are used: forward tracking, simulation extended until all particles terminate, both pathlines and endpoints generated for display.

Step 6 — Create MODPATH Model interface with particle release around well/point option

Step 9 — Run MODPATH and View Results

Click 'Run' in the Create MODPATH Model interface. After processing, the particle pathlines and endpoints appear on the MODFLOW Results display. The pathlines show where water from the injection well travels through the aquifer — following the hydraulic gradient, deflected by the low-K zone, potentially reaching the river or other discharge boundaries.

Step 7 — MODPATH particle pathlines and endpoints displayed on model results

MODPATH results detail — particle trajectories showing flow paths from the injection well area

Key Concepts

Any MODFLOW model becomes interactive: The MODFLOW Analysis Tool is not limited to models built in IGW-NET. Any standard MODFLOW model — from Visual MODFLOW, GMS, ModelMuse, or hand-built input files — can be loaded as a zip package and instantly gains cloud compute, terrain basemaps, interactive zoom, boundary condition inspection, and MODPATH integration. This makes IGW-NET a universal MODFLOW post-processing environment.

From static files to dynamic exploration: Traditional MODFLOW post-processing is batch-oriented: run the model, open results in a viewer, export images, create a report. The MODFLOW Analysis Tool is interactive: zoom in, pan, change display settings, run particle tracking, zoom to a different area — all in real time, all in the browser. The model becomes something you explore, not just something you report.

Particle tracking answers management questions: The pathlines from Step 9 directly answer practical questions: Where does injected water go? Does it reach the river? Does the low-K zone divert it? How long does it take? These are the questions that regulators, consultants, and site managers need answered — and MODPATH integrated into the analysis tool delivers them without leaving the interface.

Workflow integration: This tutorial completes a three-part sequence: Tutorial 21 (build the unstructured grid model), Tutorial 22 (visualize subgrid results), Tutorial 23 (load into the MODFLOW Analysis Tool for post-processing and particle tracking). Together, they demonstrate the full lifecycle of a variable-resolution MODFLOW-6 model in IGW-NET.

4What's Next

Continue to advanced 3D modeling and data integration:

Tutorial 24: T-PROGS 3D Geologic Model — build 3D geology from borehole lithology data
Tutorial 25: 3D Flow Visualization — immersive 3D flow fields, water table, and layers
Tutorial 26: 3D Point Data Analysis — borehole and well data in 3D

This tutorial covers