Engines & Capabilities

1Two engines. One workflow.

IGW-NET offers users a choice between two interoperable solver engines — the same conceptual model, same domain, same grid, different mathematics underneath. One click switches between them.

2Realtime cloud-powered modeling

IGW-NET is cloud-powered — accessible on demand anywhere, anytime, through an internet browser on your PC, smartphone, or tablet. There is no software or data to download, there are no operating system requirements, and simulation, analysis, and visualization are all handled on IGW-NET's server.

Data, software, platform, and computational infrastructure are provided as a service, benefiting the entire environmental / water community — researchers, consultants, educators, students, managers, and planners.

3Collaborative / participatory modeling

Because IGW-NET is web-based, it enables a new type of participatory modeling experience where collaborators from around the world operate, control, and work live on the same model. Changes and updates made by users in completely different locations are displayed to all users in real time. When one user submits a model for simulation, all users in the group simultaneously view the results.

4Realtime data-enabled modeling

IGW-NET is data-enabled — it is live-linked to a preprocessed global spatial database so you can instantly create a unified flow and transport model that can then be further refined or modified. Key global datasets include:

• Land topography and surface-water networks (from high-resolution DEMs)
• Surficial aquifer thickness
• Hydraulic conductivity of surficial aquifers / deposits
• Climate data (precipitation, air temperature)
• Static water levels
• Monitoring-well sensor data
• Land use
• Soil type and soil properties

Additional datasets are available for specific regions (e.g., the United States), and the global spatial database is continuously expanding.

Web Data Services-enabled modeling

Recently, Web Data Services-enabled modeling was added to IGW-NET — a direct link or "bridge" between DataNET WMS, WFS, and WCS service layers and IGW-NET for data import and model parameterization. Users can take advantage of a global, multi-scale "Data Tree" of existing Data Web Services — organized by region and environmental category — or they can import from external / third-party web data servers.

For a hands-on walkthrough, see DataNET Tutorial 9 — DataNET-based Groundwater Model (Maple Creek Watershed, ND).

5Realtime hierarchical modeling

IGW-NET users can interactively and on-the-fly insert models inside of models (inside of models, etc.) to characterize flow and transport processes at and across different spatial scales.

This approach lets you solve large, complex real-world hydrogeology problems as a series of smaller, interconnected problems — multiple models across different scales or areas of interest — instead of forcing everything into one enormous high-resolution model. It significantly relaxes the computational / numerical bottlenecks traditionally involved with tackling complexity.

6Realtime unstructured grid modeling

IGW-NET lets users refine the computational grid to resolve more details in key areas of interest — in the vicinity of a pumping well, or near a river or stream, where head dynamics change quickly over space and time.

The approach is based on nested grids of rectangular cells (other cell shapes are not supported at this time). Users can generate and visualize their unstructured grid within IGW-NET, or import refinement zones from an externally-created shapefile. Unstructured-grid results render automatically in the map display.

Analysis tools for unstructured grids include:

• Aquifer / zone water balance
• Cross-section visualization
• Time-series hydrographs at monitoring wells
• Particle tracking

7Realtime stochastic modeling

IGW-NET enables users to examine the impact of unmodeled small-scale heterogeneities and perform risk-based prediction through stochastic Monte Carlo simulation. Spatial parameters are represented as random fields, and flow and transport simulations are automatically recomputed for the various realizations.

Monte Carlo forward and reverse particle tracking support realtime delineation of:

• Probabilistic capture zones (forward tracking — where does water end up?)
• Impact / influence zones (reverse tracking — where did water originate?)

Monte Carlo solute transport modeling can be used to calculate the risk of exceeding MCL / threshold concentration values at locations of interest or concern.

8Immersive 3D geologic modeling

IGW-NET includes capabilities for multiscale transition-probability geostatistics (Carle, 1999) to simulate 3D aquifer-material variability. The model links fundamental observable attributes (lithology transition rates from borehole records) with probabilistic Markov-chain model parameters.

The output is a set of material classes and a visual representation on a 3D grid. The four standard classes are:

• AQ — aquifer
• MAQ — marginal aquifer
• PCM — partially confining material
• CM — confining material

Material classes can be used for groundwater modeling directly (e.g., to generate a 3D hydraulic-conductivity field). IGW-NET is live-linked to a number of statewide borehole-lithology databases and also provides an interface filter for importing external lithology datasets.

See also: DataNET Tutorial 13 — Visualizing Borehole Lithologies.

9Realtime reactive transport modeling

IGW-NET users can interactively introduce particles as tracers — at a point, in a zone, around a well or wells, or along a line — or contaminants in different modes (specified concentrations, fluxes, or head-dependent fluxes) from a variety of surface or subsurface sources, including:

• Polluted streams
• Lakes
• Injection wells
• Leaky landfills / dump sites

Particles and plume migration are instantly tracked and visualized, taking into account diffusion, dispersion, sorption, and reactions.

Solute transport can be done with the Interactive Ground Water (IGW) source code or using MT3D, which supports multi-species reactions including interspecies reactions and parent-child chain reactions.

10Realtime variable-density flow modeling

IGW-NET users can model variable-density groundwater systems — those involving temperature gradients or seawater intrusion — using the integrated SEAWAT or MODFLOW-6 "Density Flow" solver. This couples constituent transport and flow and creates visualizations with both concentration and head.

11Realtime coupled lake-aquifer modeling

IGW-NET enables lake water-balance modeling and coupled lake-groundwater modeling, accounting for:

• Precipitation
• Evaporation
• Surface runoff
• Surface-water inflows / outflows
• Groundwater seepage and infiltration

Lake levels can be computed as part of this coupled groundwater-lake interaction model.

12Realtime calibration with big data

IGW-NET allows flow-model calibration at regional scale using water-level measurements from densely populated statewide / provincial water-well databases. Calibrating regional flow models to high-density (but noisy) water-level data provides an excellent starting point for sub-scale data collection, modeling, and analysis.

Also available for calibration: USGS sensor data that can be seamlessly extracted and compared with simulated outputs. Groundwater-level time-series data can be used for both transient and steady-state model calibration — by comparing average, maximum, or minimum observed water levels to steady-state simulated head.

13Automated parameter optimization

IGW-NET supports automated parameter estimation via the UCODE auto-calibration (inverse modeling) method, based on nonlinear regression (Poeter and Hill, 1999).

Observations that can be matched in the regression:

• Head (water levels)
• Fluxes (e.g., to / from surface-water bodies)
• Concentrations

Calibration parameters that can be optimized:

• Recharge (or recharge multiplier for spatially-explicit representations)
• Hydraulic conductivity (or conductivity multiplier)
• Anisotropy ratios (K_x/K_y, K_x/K_z)
• Specific yield and specific storage
• River / stream / lake leakances
• Drain leakances

14Realtime aquifer test modeling

IGW-NET provides tools for calculating drawdown and estimating aquifer properties (transmissivity T, storage coefficient S) from observed drawdown data. Sub-tools include:

• Theis solution graphical interface
• Specific-capacity analysis
• Root-mean-square drawdown analysis
• Automated estimation of T and S (based on an initial guess)
• Curve matching (type curves and pump-test data)
• Confined, leaky, and unconfined aquifer support
• Slug test analysis — methods: Hvorslev (1951), Cooper (1967), and Bower-Rice (1976)

15Realtime data analysis tool

An analytics tool is available for visual and statistical exploration of scatter-point data, including:

• Histogram, PDF / CDF
• Spatial and temporal analysis of parameter values
• Data-density distribution visualization
• Spatial interpolation (2D or 3D) using Inverse Distance Weighting or Kriging with variogram modeling
• Linear regression analysis
• Outlier analysis and removal

16ZipMODFLOW post-analysis tool

In addition to the real-time tools, IGW-NET users can load, run, and visualize previously completed MODFLOW models using the ZipMODFLOW post-analysis tool. You can take most any MODFLOW model and:

• Inspect the boundary conditions
• Run the model
• Inspect cross-sections
• Do basic calibration
• Perform MODPATH particle tracking
• ...and more

17Global Model Network & Instant Intelligent Reporting

IGW-NET is directly linked to a Global Model Network, allowing users to selectively share model results (images, plots, animations) and / or the model and its data.

IGW-NET's Intelligent Report System automatically and instantly converts "incomprehensible" low-level model inputs, options, and settings into a high-level report summary of the model representation — easy for a general audience to assimilate. Users choose what and how much to make public.

18Realtime situational help

IGW-NET's user reference material is situationally embedded inside the modeling platform interfaces and submenus — real-time help buttons provide instant access to sub-pages explaining how to use different options or features.

The Realtime Help pages are continuously improving and will include not only technical reference material but also links to related scientific material (typical parameter values, numerical / computational aspects, etc.). Eventually, the goal is to let users model without a manual.

19Action-oriented curriculum

IGW-NET is supported by a comprehensive set of web materials for groundwater education and learning the various tools. The action-oriented groundwater curriculum consists of:

• Engaged-learning lessons
• Short problems and exercises
• Integrated capstone projects
• Video lectures and demos
• A Digital Library of model animations and visualizations

Problems and projects can be edited, customized, and refined by instructors based on their specific course learning objectives / curricular expectations. New content can be added directly to the Curriculum Network through IGW-NET's embedded editing system.