Groundwater Modeling Software

AnAqSim (analytic aquifer simulator) is a groundwater modeling tool that can cover a range of needs from the simplest 2D capture zone simulation to moderately complex 3D and transient simulations.  It employs the analytic element method (AEM) in a unique way that allows fully transient modeling, multi-level aquifer systems, and anisotropy.


Dr. Charlie Fitts, author of AnAqSim and the textbook Groundwater Science, 2nd ed.,  has over 35 years experience with groundwater and geotechnical consulting, and is available for consulting on groundwater modeling projects.

AnAqSim (analytic aquifer simulator)


Gain more insight in less time

A quick alternative to MODFLOW and other numerical methods for modeling cases that range from simple to moderately complex.

Comprehensive capabilities

AnAqSim is the most versatile and capable analytic element method software:  multi-layer 3D systems, full transient capabilities, heterogeneity, anisotropy, fresh-salt interface aquifers, and a full suite of line boundary types.

Many uses

AnAqSim has been used to simulate groundwater remediation designs, mine and construction dewatering, infiltration mounding, regional aquifer flow, capture zones, well field impacts, fresh/salt interface flow in coastal aquifers, pathlines, advective transport, and embankment seepage.

Learn More

Featuresspecificationstutorials and videosUser Guide.


 Video overview of AnAqSim:

Release 2017-1 has new features for pathlines, surfaces, and more

Release 2017-1, a major release, is now available with these and other new features:

  • Surfaces for spatially-variable top and bottom conditions (recharge rates, leakage rates, heads that top or bottom layer leak towards)
  • Pathlines that start from points equally spaced within a polygon area
  • All pathlines (single, line, circle, area, and well) can now start at multiple levels instead of just one level
  • Capture zone constraints: constrain the display of pathlines to only those pathlines captured by selected wells or line boundaries. Used for zone of contribution analyses.
  • Improved display of pathlines in vertical profile plots – now plots each trace as a continuous line with dots at each time marker

Please see the release notes for a full list of new features.

Some 2017-1 highlights are shown in the model at right

Area pathlines started within the red polygon (e.g. contamination source) at the water table in a four-level area of the model. The pathlines are drawn into a shallow permeable remediation trench in the top layer (100x higher K than the aquifer), and most are captured by a pumping well at the right end of the trench.

A vertical profile through the trench shows these pathlines in cross section.  Most are drawn into the trench and well, but some are not captured and continue deeper below the downstream end of the trench.  Water flows up into the left end of the trench and down out of the right end of the trench.  Some pathlines appear to start above the water table; this is due to the fact that the pathlines are projected on to the line parallel to the trench, but the head profiles are exactly on this line.

The same plots, but constrained to display only those pathlines that end at the well, are shown at right.  The starting locations in this plot define the portion of the source area that is captured by the well.  Capture constraints are useful for remediation design and “zone of contribution” studies.

All of these pathlines are drawn up into the trench and then captured by the well.  Most have a several week residence time in the trench.

3-D Dewatering Example Model Posted

Many users are solving transient construction and mining dewatering problems with AnAqSim, so we have created an example model to show how to create such models.  This model is of a construction dewatering system that includes a partially-penetrating sheet pile barrier, three partially-penetrating wells within the barrier, and a recharge trench outside the barrier where well discharge is injected back into the aquifer.  The model has 7 layers in the system area and is transient with two phases of pumping. See the model and its results and download the model files.

What AnAqSim users have to say

We recently purchased two AnAqSim licenses and have had a lot of success with it. We have since built a good portfolio of multi-layer models that have been successfully simulated with AnAqSim and benchmarked against other software. We are starting to use it a lot.

Stephen Thomas

Technical Director, OGI Groundwater Specialists, UK

AnAqSim is an easy to use, powerful, and cost effective AEM software that keeps getting better with every new release. I have used it successfully on a number of consulting projects including wellfield permitting, remediation design, site characterization, saltwater intrusion studies, and mine hydrology investigations, and it has worked well for all my applications. Whenever I have questions or need help with AnAqSim, Fitts Geosolutions always responds quickly and thoroughly. I would recommend AnAqSim to any groundwater flow modeler, beginner or expert.

Katie Feiner

Associate, McLane Environmental, New Jersey

I use AnAqSim for estimating the potential impact of 1) leaky wells in multi-layer aquifer settings linked with calibration constrained uncertainty analysis (via PEST); 2) rapid impacts assessment of quarry/mines.  The prompt and helpful support offered by the software developer has made understanding the principles behind the AEM method relatively easy to grasp.  I would recommend AnAqSim to anyone who requires a rapid groundwater impact assessment method.

Mark Hocking

Hydrogeologist , Hydro Geo Environmental Consulting (HGEC), Australia

I am new to AnAqSim but have already learnt some useful tips and tricks which I can apply to other modelling applications such as Modflow. The developer quickly replies to my queries and provides lengthy explanations when needed. I purchased the flexAEM tutorials with the AnAqSim software and have found these to be extremely helpful in learning how to properly set up my models. I have successfully used AnAqSim to approximate stream depletion solutions for Jenkins (1968), Hantush (1965) and Hunt (1999) type settings.

Simon Harper

Senior Groundwater Scientist, Hawke’s Bay Regional Council, New Zealand

Join the Growing List of AnAqSim Users

Satisfied AnAqSim users span the globe: North America, South America, Europe, Asia, Australia, and New Zealand.  Some work in consulting, some in research, and some in government agencies.