Developments in computer technology, computer programs, and databases have significantly increased the use of computer modeling in water resources and environmental management. In response, Matrix’s capabilities in computer modeling and analysis have become an increasingly important aspect of our work in water resources development, permitting, aquifer test analyses, and environmental applications. Our computer modeling expertise encompasses numerical and analytical groundwater flow modeling, aquifer test analysis, and contaminant mass transport. We are familiar with the latest versions of the published models and pre-processors accepted by federal and state regulators.

Modeling Projects
Matrix has developed groundwater models for numerous projects to support applications for Assured and Adequate Water Supply (AAWS), Underground Storage Facilities (USF), Aquifer Protection Permits (APP), adjudication of Water Rights Settlements, and compliance with National Environmental Policy Act (NEPA) and Endangered Species Act (ESA) requirements. These projects range from local site-specific models of relatively small areas to models of regional and sub-regional hydrologic systems.

Matrix uses and adapts the latest regional groundwater flow models published by various government agencies, including the U.S. Geological Survey (USGS) and the Arizona Department of Water Resources (ADWR). Model details, assumptions, and upgrades are frequently discussed with USGS and ADWR model authors. Matrix keeps the regional models up-to-date, incorporating all of the most recent Assured Water Supply (AWS) approved demands. Matrix has used the models extensively for groundwater resource and 100-year impact evaluations, developing a unique proficiency at adapting the models to support our clients' projects and requirements.

In addition to possessing the requisite mathematical, statistical, and computer skills; Matrix professionals have in-depth knowledge of local and regional hydrogeologic conditions, and years of experience working with water policy makers and regulatory agencies. Matrix modelers also know the limitations of computer models – that models produce information, not decisions. A key aspect of Matrix’s groundwater modeling expertise is our ability to understand and communicate the assumptions upon which a model is based so that the model results can be defended.

Advanced Flow Modeling
Matrix modelers implement state-of-the-art modeling techniques, allowing the team to employ the latest scientific advancements in advanced groundwater flow modeling. Matrix employs the latest version of USGS MODFLOW codes, including unstructured grid control volume finite difference (MODFLOW-USG) and the Newton-Raphson finite difference (MODFLOW-NWT) formulations. Matrix conducts pre- and post-processing using popular software tools like Groundwater Vistas© and Visual MODFLOW©, but also takes advantage of the geoprocessing power of ESRI GIS software and the three-dimensional (3-D) visualization capacities of Earth Volumetric Studio (EVS). Matrix makes use of advanced model calibration and uncertainty analysis capabilities of the PEST suite of software tools, including Tikhonov regularization, truncated singular value decomposition, and null space Monte Carlo analysis. A wide array of tools is available to modelers today, and the Matrix team knows how to select the right tools to meet the needs of our clients for efficient and effective model development and presentation.

Contaminant Transport Modeling
Subsurface contaminant movement is highly site-specific depending on multiple variables, including the hydrogeological, chemical, and biological characteristics of the porous media and the contaminant chemical properties. Understanding the complexities of these systems is extremely important to be able to build a model to predict contaminant movement and the effects of remedial efforts looking forward. Matrix understands these subsurface complexities and regularly conducts fate and transport modeling to support clients with various types of unique challenges, including groundwater remediation sites that involve pump and treat systems and in situ methods, artificial groundwater recharge facilities, and mining. These models range from simple analytical screening models such as BIOCHLOR to particle trace analyses using MODPATH to full three-dimensional reactive chemical transport models using MT3DMS. Matrix modelers know how to select the right tool for the task at hand.

3D Modeling Capabilities
Matrix offers 3-D modeling capabilities utilizing Earth Volumetric Studio (EVS). Our use and understanding of EVS software along with the team’s multidisciplinary experience allows us to provide clients state-of-the-art capabilities for analyzing and visualizing subsurface data. Applications include:
Evaluation of site assessment data (soil and groundwater)
Remedial strategies and monitoring
Groundwater modeling simulations, litigation support
Regulatory reporting
Public relation presentations

We incorporate into our models site specific parameters such as hydrostratigraphic data, analytical data, groundwater level data, geophysical data, infrastructure information, GIS information, water levels, analytical data, AutoCAD drawings, aerial photographs, computer model outputs, subsurface characterization tools (CPT, MIP), and geophysical survey data.

The use of EVS has become the foundation of Matrix’s site characterization approach, which we use to evaluate complex hydrostratigraphic environments, potentiometric surfaces, water producing zones, contamination pathways, and contaminant volume. This characterization provides a solid basis for developing conceptual models, a critical first step in developing numerical models. EVS is also used to visualize groundwater and solute transport modeling results which can be performed from third party modeling systems such as USGS MODFLOW, MT3D, GMS©, Groundwater Vistas© and Visual MODFLOW©. Matrix’s 3D modeling capabilities are key to meeting our clients’ desire for excellence, whether the objective is to maximize the efficiency of remediation efforts or visualize the quantity and quality of groundwater resources. Providing industry-leading hydrogeologic solutions that exceed clients’ expectations is our goal and shared priority.