April 11, 2021

Analytical Multiaquifer Groundwater Modeling Program

(Multi Layer Program Unsteady State)

MLPU is freeware as of April 2nd, 2007        

Induced by the persistent interest in MLPU (still in 2021!), here's an announcement to clarify a few things.

In my opinion, MLPU is really outdated now. It was written in the early nineties of the 20th century, and since 2000 only small bugfixes have been applied plus a few improvements.
Although it still has features to be found in no other analytical groundwater modeling software, I think you'll have a much better deal with MLU for Windows, see here:, => Download,
or if you're familiar with Python, get TimML (TimML and TimML on github).

Please take notice of this:
MLPU will only run on single-core CPU's. When run natively on multi-CPU or multicore-CPU motherboards, Windows XP will crash and may even hang completely.
Windows 10 and many other modern operating systems don't support 16-bitprograms like MLPU anymore. But there is DOSBOX ... and maybe other DOS emulators. These allow you to run MLPU on Windows 10 (also on multicore systems) and you'll enjoy very fast computations.

What is MLPU?

MLPU is a user-friendly, fully interactive multiaquifer groundwater model running in a DOS-box. It works more or less like the Analytic Element Method (AEM). It has been designed for rapid analysis and simulation of 3D groundwater flow at a local or sub-regional scale and as such it is especially suited for analysis of groundwater pollution situations, pumping tests and/or design of building pit dewatering schemes.

The model can be used for modeling steady state and transient groundwater flow. It can also be used for optimization of hydraulic parameters given data on groundwater heads or groundwater head changes (e.g., pumping tests).

Results are displayed in the form of horizontal (XY) contour maps , vertical cross-sections or 3-dimensional perspective views (all with 3D pathlines with optional travel time indicators), time vs. head graphs or text menus.

Its mathematical background is largely based on well-known literature solutions.

A more elaborate description of MLPU and its practical use is given in a Conference poster

There were attempts to build a Windows version using OpenWatcom; this implied porting the GUI to C++ while leaving the number crunching as it is Fortran. Because OpenWatcom is multi-platform, it could later be ported to Linux and optionally OS/2.
But alas, lack of time sneaked in.....

Features | Requirements | How to obtain MLPU / download a demo | How to contact the author


MLPU started as a hobby project in 1989, aimed at learning more about 3D groundwater flow and more specifically, analytical multi-aquifer solutions. Another motive was that available analytical multi-aquifer software was outrageously, if not prohibitively, expensive at that time.

Over the years the program grew slowly. When I saw a feasible analytical solution for a specific situation I encountered in my professional occupation, I tried to build it in, yet preserving small size, speed and ease of use.

MLPU exists in its current state already since 1994; it has been used regularly since then. Its predecessor, the simpler and steady state program MLP has been around even longer. Getting the program ready for other users (testing and more testing, remodeling the user interface, writing a manual) went a bit slow due to lack of time. MLPU was first presented to a broader audience in the Analytic Element Conference in Nunspeet in April 1997. The poster description is reproduced on this website (Click here to see it).

Since April 2, 2007 MLPU has been made freeware (but no Open Source!). This has been motivated by the appearance of other analytical multi-aquifer software, like TIM (OSS); MLAEM (proprietary, but freeware for Dutch customers) (Mind you! I don't know if the links on the archived web page still works!); MWELL (proprietary); etc.
I have started programming a Windows version already at the end of 1998 or so, but given the small and highly specialized market (only some tens of customers) the ratio of
potential revenues (not just the financial one!) versus time to be invested was simply to small.

You can still obtain MLPU (including a manual in .pdf and a collection of test & validation models) free of charge by sending an e-mail to the author (address see below). But please take notice of the message at the top of this web page.

Year 2000 compatibility

MLPU nowhere uses dates (only numerical quantities expressed in days or years), so it is very unlikely that MLPU by itself would cause problems with the year 2000-bug.
Yet as the program is written in MS-Fortran and Turbo-Assembler, whose inner workings are unknown to me, I cannot guarantee absolute Y2K compatibility.
Another aspect is that MLPU uses files to read from and write to, and these files have date attributes. As the various file manipulation routines are in fact operating system routines, MLPU's Y2K compliance is also dependent on the operating system's Y2K compliance.
Finally, the underlying hardware also determines Y2K compliance of programs running on it.
Tests run by me on my two Y2K compliant computers, and on one old non-compliant notebook fitted with Y2K software, showed no problems.
All in all, Y2K problems cannot be ruled out, but are very unlikely.

Compatibility with modern MS Operating systems

I have ran MLPU myself under DOS, Windows 3.1, Windows 95, Windows 98, Windows ME, Windows NT, Windows 2000 Pro & Windows XP, without problems (see below for multicore). I even ran it under OS2 Warp 3, Warp 4, eComStation and various Linux distros, the latter using a DOS emulator.
Given this behaviour, I see no problems in running current MLPU versions in any Microsoft based OS.

However, be warned: MLPU has been found to hang on dual CPU systems, and hang Windows with it; you have been warned...)


MLPU assumes aquifers and aquitards to be isotropic, laterally homogeneous and of infinite extent. Wells in a particular aquifer are assumed to be screened completely. Dupuit-Forcheimer conditions are assumed valid. These are quite regular assumptions for simple analytical models. If any of these limitations is crucial for your specific problem, numerical models may perform better.

Features | How to obtain MLPU / a demo | How to contact the author | Back to start of home page

Requirements - What is needed to run MLPU?

Requirements | How to obtain MLPU / a demo | How to contact the author | Back to start of home page


Capacities (many capacities can be increased (somewhat, to some limit) on demand - contact the author)

Inverse modeling capacities:

Special features

Requirements | Features  | Back to start of home page

How to obtain MLPU and how to contact the author |

MLPU is freeware as of April 2nd, 2007. 

Support : Only available for customers who have previously paid for the commercial version. That said, I'll do what I can to help people using MLPU, but -be warned- my time is very limited. In principle support is only pertaining to program operation and/or previously unnoted program errors, rather than program applications.

From experience I know there are just a few people on Earth interested in analytical groundwater models, and just a hand full for multi-aquifer analytical models. That is the reason I have no downloads here (yet) - by requesting interested people to ask me I hope to get an idea of what people use this software. You can obtain MLPU (including a .pdf manual and a set of test and validation models) by e-mailing me or writing to:

P.R. Nienhuis
Eerste Oosterparkstraat 183
The Netherlands


I don't need full personal details - an e-mail address (if needed, just a temporary one) to sent the files or download URL to will suffice.

Some links to other web sites on groundwater modeling

  • ASCE Geo-Institute WWW site, contains a long list of groundwater and seepage models
  • Scientific Software Group, a lot of groundwater / transport / optimization etc. models
  • US EPA Kerr Lab, contains database of groundwater models
  • Hydrogeologists' Home page, contains a list groundwater models
  • The Geotechnical and Geo-environmental Software Directory details several hundred programs, software publishers and suppliers in the fields of Geotechnical Engineering, Engineering Geology, Hydrogeology, Geo-environmental Engineering, Data Analysis and Data Visualisation. It also links to other Web pages with related software.
  • MicroFEM, in case you need a very flexible numerical finite element groundwater modeling package.

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    Examples of graphical MLPU output

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    Horizontal XY map

    This example pertains to a fictitious 4-aquifer system. Three abstraction wells are screened in the second aquifer, three injection wells in the third. For the sake of clarity only the head contours in those aquifers are shown. Some streamlines flowing to the northernmost abstraction well (blue/green) and some streamlines emanating from the southernmost injection well (dark red) are shown. All streamlines show time steps on every 5-year interval. A DXF background (fictitious) map is shown in grey. The map border shows tick marks on rounded intervals.
    Horizontal maps can be used to show piezometric head contours (at any model time), groundwater table elevations, head differences across separating layers etc. Other options are: a cross-section trace, lay-out of analytic elements and observation wells. Zooming in and specifying a cross-section trace is done using the mouse. Heads (at any model time), contour map values, discharge components in any aquifer (at any model time), infiltration rates (at any model time), saturated thickness of first aquifer etc. can be requested by moving the mouse cursor in the map and typing a key letter. In addition, in this way time vs. head graphs can be requested for any location under the mouse cursor; info on analytic elements and observation wells (including posting of time/head data) will be echoed on request; streamlines can be started at any location at any depth (at any starting time).

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    Vertical cross-section

    In this picture five streamlines are shown infiltrating at 10,000, 8,000, 6,000, 4,000 and 2,000 m from an abstraction well in a semiconfined four-aquifer system. The second aquifer comprises two layers, the upper layer has a permeability of 5 times the lower one. Time steps are shown for every 250 year interval. Also shown on top are cross-sections of the piezometric head contours. As you can see, the red head contour shows a deep cone, relating to the large abstraction of the well in the 3rd aquifer.
    Zooming in into a part of the cross-section can be done using the mouse.
    It may be interesting to note that this model file is one of MLPU's verification files. By computing inflow at the infiltration location of each streamline in all aquifers and comparing that to the depth at which the streamline enters the well screen, a very elegant check can be made regarding continuity of flow. Also the effects of aquifer layering on streamline accuracy can be checked, with the well either in a layered or in a homogeneous aquifer. As you may expect, MLPU's streamline computations comply to this test.

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    3-dimensional perspective view

    This 3D perspective view is from a real world situation, somewhat simplified for clarity's sake. A water supply well field with deeply screened production wells is threatened by polluted groundwater. A number of less deeply screened interception wells is emplaced to protect the well field. The picture shows some streamlines entering one of the interception well at two levels. All wells are shown in black; the streamlines are color coded after the (model) aquifer they are crossing through.
    These 3D perspective pictures can be tilted and rotated; vertical exaggeration and perspective can be increased or decreased, all fully interactively.

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    Time vs. head graph

    This time/head graph shows results of a pumping test in a two-aquifer system. To be able to model vertical flow adequately, the upper aquifer was subdivided into 6 sub-aquifers and the lower aquifer into 2. So a total of 8 model aquifers and 7 leaky layers (+ a top aquitard with storage) had to be modeled. The graph is computed for coordinates (0, 0); the pumping well is located at (0, 0) and screened in aquifer 5.
    MLPU's T/h graphs can be drawn with two linear scales, logarithmic time scale, logarithmic and negative logarithmic head scales. In this example drawdowns have been plotted, but graphs of absolute heads vs. time can be plotted as well. Posting of measured data is easily done: put them all together in one ASCII file (in the proper order and with some extra info) and MLPU will sort out which data to plot in what color, depending on location of the T/h graph and either the specified aquifer or the specified observation screen depth. In the latter case MLPU also sorts out in which model aquifer the observation well is screened - handy if you need to change the aquifer scheme (which may be frequently needed in this type of pumping tests).

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    Last updated 11 April, 2021

    BTW this page is deliberately kept simple so that it can be read with any browser

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