MODFLOW is the groundwater modelling software developed by the U.S. Geological Survey (USGS). It appeared in 1984 and has had a constant developement till now. MODFLOW’s capacities allow the representation of regional or local groundwater flow and its interaction with superficial water bodies.

Given that MODFLOW is a free source code (it’s distributed without charge), there has been a wrong perception about the program being outdated or having a lesser capacity than its commercial peers. This article lists some of the points for which MODFLOW is better than other groundwater modelling softwares.

Every modelling software is a numerical aproximation of the complex nature. There’s no such thing as the “best” modelling software, and simulation quality depends on the modeler’s criteria and input data.

Why is an open software better?

A truly open software means having the freedom to download, install, and modify the software without any charge, like MODFLOW. The decision about MODFLOW isn’t essentially based on price, although it’s a good point to take notice. The main reason of choosing MODFLOW is the information’s transfer versatility, simulations transparency, and water resources management dialogue.

Groundwater modelling of an Andean basin with MODFLOW and Model Muse

Why is MODFLOW better?

1. Because it’s free and has no charge. MODFLOW, being developed by a public U.S. institution, is distributed freely. There are commercial pre and post interfaces; nevertheless, USGS has developed a high performance pre and post interfase called Model Muse.

2. It’s well documented. Each part of MODFLOW has its manual; that is to say, each part of the software that represents a relevant physical process to groundwater flow has its own document about the main considerations taken in the simulation.

3. MODFLOW is modular and continuously updated. MODFLOW’s newest version is MODFLOW 2005 v1.9 which is from May, 2012. Given its modular structure, different packages can be attached to MODFLOW like the unsaturated flow package (UFZ) or the local refinement package (LGR).

4. MODFLOW is based on finite differences. Given its rectangular cells division, the volumetric control of what enters and exits is pretty accurate and isn’t a simulation problem. This control is also fulfilled in conditions that vary with time, having an exact control of water coming from storage.

Finite differences cell scheme and its associated flow.

5. MODFLOW represents well the physical processes related to groundwater flow. The evapotranspiration, which is the process that can discharge up to 65 % of groundwater, is well configured in MODFLOW and runs without major computational requirements. Lakes and river interaction packages are attached in the code well.

Which would be the next step in groundwater modelling softwares?

We believe that the next software that surpasses MODFLOW should be developed by a community with the support of several institutions. That would give plenty dynamism to the development of new tools.

Also, the new code should be written in a different language than Fortran, like C, with parallel computing capacity.

Windows environment is not the best for optimizing a processor’s capacity, due to the resources devoted for the graphical interface. Superior softwares may be based in Linux.