💧 IGW-NET Documentation

Groundwater modeling end-to-end — from global data to defensible decisions. IGW-NET runs MAGNET's own IGW solver and the USGS MODFLOW family natively. Real aquifers tied to real data, or the classical conceptual problems where the mechanism itself is the subject — Tóth flow, capture zones, plume migration. Both are first-class.

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Native engines: IGW and the USGS MODFLOW family. IGW-NET runs MAGNET's own IGW solver — often more efficient and robust than equivalent MODFLOW runs, mathematically identical under same assumptions, parameters, and discretization. The MODFLOW family is also a native execution engine. IGW-NET models export as MODFLOW files; raw MODFLOW files open in IGW-NET's visualization mode. The translation is one-way by design: IGW-NET works in continuous xyz,t space with conceptual objects (points, lines, polygons); MODFLOW is grid-bound. That asymmetry is what lets IGW-NET stay conceptually expressive at any scale.

Six Pillars of IGW-NET Documentation

Each pillar serves a distinct user need. Start wherever matches your question.

📖 Beginner's Manual — by Dr. George F. Pinder

A 111-page science-first introduction to groundwater flow and transport modeling with IGW-NET. Ten chapters cover model philosophy through transient transport, with 98+ annotated screenshots. Written by Dr. George F. Pinder (University of Vermont; founding editor, Advances in Water Resources) — the natural entry point for students and anyone new to groundwater modeling.

Groundwater Flow & Transport Modeling with IGW-NET

Dr. George F. Pinder, with Drs. Curtis, Li, and Liao
10 chapters · 98+ annotated screenshots · 111 pages

Covers the fundamentals: Darcy's law, governing equations, conceptual model development, boundary conditions, model execution, calibration, and contaminant transport. Uses IGW-NET as the vehicle for teaching groundwater science — complementary to the Users' Reference Manual, which focuses on the platform itself.

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📘 The Users' Reference Manual

Comprehensive 22-chapter reference covering the full modeling workflow — applicability, domain setup, aquifer attributes, vertical layering, boundary conditions, calibration, stochastic methods, and 33 common pitfalls with interface-based diagnostic recipes. Where Pinder's Beginner's Manual teaches the science, the Users' Reference Manual teaches the platform.

Open the full Users' Manual — all 29 chapters →

🎓 31 Quick Tutorials

Progressive skill-building — from your first 2D model through Monte Carlo uncertainty, 3D visualization, T-PROGS geology, and DataNET integration.

1
2D Steady Flow
Domain, boundaries, first simulation
2
Nested Models
Child inside parent, auto BC inheritance
3
Particle Tracking
Capture zones, wellhead protection
4
Water Balance
Inflows, outflows, storage analysis
5
Contaminant Transport
Plumes, dispersion, real-time migration
6
Vertical Layers
3D architecture, confining units
7
Transient Modeling
Time-varying pumping, seasonal recharge
8
Calibration
Match model to observations
9
Synthetic Model
Random heterogeneous aquifers
10
Aquifer Layers
Multi-layer systems, borehole data
11
Model Hierarchy
Multiscale parent-child analysis
12
Profile Modeling
Vertical cross-section, seepage, dams
13
Import Shapefiles
External GIS data into your model
14
Post-Analysis
Results, videos, scenario comparison
15
Stochastic Flow
Correlated random K fields
16
Monte Carlo Flow
Hundreds of realizations, uncertainty
17
MC Transport
Probabilistic plume, MCL exceedance risk
18
Probabilistic Capture
Monte Carlo wellhead delineation
19
Auto Calibration
PEST-based parameter estimation
20
Theis Solution
Pumping test analysis, T and S
21
Unstructured Grid
Nested refinement near wells, plumes
22
Unstructured Results
Analysis on refined grids
23
MODFLOW Analysis
Import external MODFLOW models
24
T-PROGS Geology
3D heterogeneity from borehole lithology
25
3D Visualization
Heads, vectors, pathlines in VTK
26
3D Point Data
Statistics, interpolation, iso-surfaces
27
DataNET Model
Model from federated web data services
28
Data & Regression
Noisy well records, filter, regression
Browse all 31 quick tutorials →

💡 Modeling Concepts

The IGW-NET modeling playbook: high-value groundwater concepts that explain system dynamics, data, calibration, sensitivity, scale, transport, surface water, and model interpretation.

01
Global Does Not Mean Coarse
Why the global base model is already physically rich, high-resolution, and useful before local customization begins.
02
Structural Dynamics vs Perturbations
Stop reinventing groundwater systems; understand where local reality deviates from the larger hydraulic structure.
03
Turn Any Location Into a Working Groundwater Model
Reusable system fabric changes groundwater modeling from manual assembly to computational steering.
04
Many Noisy Observations vs Few Precise Measurements
Regional spatial comparison and local temporal calibration from national well data systems.
05
Sensitivity Analysis as Perspective Building
Not everything matters equally — fast sensitivity analysis shows where effort should go.
06
Hydraulic Remoteness
Why regional parent models make local boundary placement less fragile.
07
Geological Layers vs Computational Layers
Hydrostratigraphy is not the same thing as numerical vertical resolution.
08
Numerical vs Physical Dispersion
Robustness, numerical dilution, refinement, and transport realism.
09
Three Surface-Water Representation Levels
Fully coupled SW-GW, mapped hydrography as boundaries, or emergent DEM drainage.
10
Lidar-Enabled Groundwater-Dependent Ecosystems
Fragile headwaters, seeps, wetlands, and coldwater streams need resolution.
11
Vadose Zone via SwaNET/INFIL
Why coupled-model recharge beats in-IGW-NET infiltration.
12
Darcy Applicability at Scale
EPM defensibility in karst, fractures, and conduits.
13
Stream vs Drainage Precedence
Avoiding double counting while allowing hydrologic emergence.
14
Surface Drainage as Wetland Predictor
Why wetlands and seeps can emerge from groundwater solutions.
Browse all modeling concepts →
For detailed field names and terminology, see Users’ Manual Chapter 22 — Fields.

📚 Case Studies

Real-world modeling projects walked through end-to-end — concept model, data sourcing, simulation, calibration, interpretation. See how experienced modelers approach full projects.

🛠️ Realtime Help

Realtime Help is more than a reference library — it's the knowledge layer of the platform. Modeling concepts, governing science, numerical methods, per-element operational help, visualization guidance, and the foundational engine references — organized hierarchically so you can stop at any depth and still have what you need. Especially deep on aquifer flow, transport, conceptual modeling architecture, and the IGW and MODFLOW family of solver engines.

💧 Browse the IGW-NET Reference Library
Per-element reference for every IGW-NET UI component, hierarchically organized — open the dedicated reference index to navigate by topic area.

What's inside: Map navigation · grid setup · boundary conditions · pumping wells · transport · particle tracking · calibration · uncertainty · 3D visualization · model output

Why a separate index? Flat lists hide structure and overwhelm. The reference library groups related topics into clear categories so you find what you need in seconds, not minutes.
Map UIBoundary ConditionsWells & PumpingTransportCalibration3D Visualization
Open Reference Library →
Browse all 180 realtime help pages →

📚 USGS MODFLOW Family References

IGW-NET is built on the USGS MODFLOW family — the international standard for groundwater modeling. These are the authoritative reference manuals and software pages for each engine, hosted by the U.S. Geological Survey.

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MODFLOW 6

Current core engine — control-volume finite-difference, structured and unstructured grids, multi-model coupling
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MODFLOW-2005 & MODFLOW-NWT

Legacy core engines — the most widely used historical MODFLOW versions; NWT solver handles dry cells in unconfined aquifers
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MT3DMS & MT3D-USGS

Solute transport — multi-species advection, dispersion, sorption, reactive decay; MT3D-USGS is the actively maintained USGS continuation

MODPATH

Particle tracking — capture zones, travel times, wellhead protection, contaminant pathlines (forward and reverse)
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SEAWAT

Variable-density flow — saltwater intrusion, brine migration, coupled MODFLOW + MT3DMS for density-dependent flow and transport

🤖 Or ask the IGW-NET AI

Trained on all six documentation pillars. Answer workflow questions, interpret errors, point you to the right dialog or chapter.

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