iMOD User Manual version 4.4 (html)

11.12Tutorial 12: Pumping Tool

This tutorial gives a brief introduction to a more advanced Pumping Tool which serves to simulate new features within an existing model configuration. It is advised to get familiar with Section 11.6 that handles the most regular model simulation. See for more detailed references regarding the Pumping Tool Section 7.11.


This is what you will do:

Required Data

For this tutorial you need the following iMOD Data Files/folders:

Getting Started

Note: {installfolder} refers to the full path of the directory you installed iMOD in (e.g. D:\iMOD).

Quit often it is necessary to display a map for orientation. In this example we use the initial computed phreatic groundwater head located in the folder TOPBOTTOM \HEAD_STEADY-STATE_L1.IDF.


Figure 11.159: Start of the Pumping Tool.

Note: As long as the Pumping Tool window is active it is possible to use most of the general functionalities of iMOD. Be aware that entering e.g. the Cross-section Tool, the 3-D Tool closes the Pumping Tool.

Configure dewatering system

Let us construct a simple dewatering system that consists of 5 extraction wells along a single strip.

In the Well Systems window, you can define how the dewatering system (or some equivalent, e.g. Aquifer Recovery System (ARS), Aquifer Thermal Storage (ATS)) is configured. You can specify for each date an extraction rate; alternatively, you can read a comma-separated-values file with that information. Let’s do that.

The EXTRACTIONRATES.CSV file contains one descriptive header and two columns; column one stores the date (yyyymmdd) and column two the extraction rate (m\({}^{3}\)/hr), see below the content of the file:

20110918, -10.0000000
20110923, -25.0000000
20110928, -50.0000000
20111023, -60.0000000
20111028, -10.0000000
20111102, 0.0000000

iMOD will read the data and put it in the table. Be ware that the last entry of -999.0 is irrelevant, iMOD is ignoring the Q-entry or the last record. Let’s make a graph of the extraction rate.


Figure 11.160: Example of the entered well strength.

Each extraction rate is defined by its starting date, therefore a bar is drawn from that moment until another rate is specified. Let’s define the filter positions.


Figure 11.161: Example of the entered well filter screens.

The FILTERPOSITIONS.CSV file contains for each extraction filter, its label (e.g. Well 1), vertical position (top and bottom of the screen) and its horizontal position (x,y coordinates), see below for the content of the file.

‘Well 1’, 0.00, -2.50,145732.28,448621.03
‘Well 2’, 0.00, -2.50,145667.50,448673.47
‘Well 3’, -5.00,-10.00,145608.89,448725.91
‘Well 4’, -5.00,-10.00,145550.28,448778.34
‘Well 5’,-15.00,-20.00,145491.69,448821.53

iMOD assigns the well to the appropriate model layers automatically. Moreover, as this well system consists out of multiple wells, the strength that we just assigned is distributed over the different wells (1 up to 5) according their sum of transmissivity along the individual well screens.

iMOD will save the file DEWATERING.ISF in the folder {IMOD_USER} \PUMPINGTOOL. The file is editable by e.g. NotePad, although it is not advisable to change the file outside iMOD.

Effect Computation

Not much else is needed to start a model simulation.


Figure 11.162: Example of the Results tab.

The Compute Result(s) window shows the most important settings that can be changed before a simulation starts. These are very limited, compared to the settings that can be changed in the Model Tool (see Section 7.9). In this tutorial we experiment with a model configuration for a Mean Summer Situation and a Mean Winter Situation.

There will be a window opened that contains the following information.

Check-result for:

Non-existing files:

Line No. Filename

All files exist !!!

So, this means everything is okay, we’re ready to go.


Figure 11.163: Example of the Compute Results window.

The current model simulation consists of one initial steady-state simulation and 8 intermediate stress periods. The distribution of stress periods is defined automatically by the occurrences of extraction rates. The cell size of the model is 25 meter and around the maximal extent of the set of wells, a buffer is included of 1500 meter.

iMOD will create a prjfile in the folder {IMOD_USER} \PUMPINGTOOL \DEWATERING \
V1_MeanSummersituation \MODEL.PRJ (i.e. the actual and modified modelconfiguration) that consists of the extraction wells of the dewatering system as well. iMOD computes the strength for each of the individual wells and assigns them to the appropriate model layer based upon their screen depths. These will be saved in a separate IPF files {IMOD_USER} \PUMPINGTOOL \DEWATERING \V1_MeanSummersituation \WELLS \WELL*.IPF. Afterwards you can (re) uses those files for visualization and/or direct use in another PRJ of RUN file. Finally, iMOD creates a MF2005 structure and runs the model(s).


Figure 11.164: Example of the Drawdown results for the entered pumping regime at 2\(^{\rm nd}\) of November 2011.

iMOD will open the selected IDF-file in the iMOD Manager (see Section 5.4). It is advisable to check the extent of the drawdown for each model layer to see whether the applied buffersize is appropriate. In other words, the drawdown may not reach the boundary of the model area significantly.

Adding Observations

Let us add an observation wells that was measured during the dewatering.

Let us define the horizontal and vertical position of the current observation.


Figure 11.165: Example of the Time series of the added observation.

Read Section 7.11.3 for more detailed information about adding and changing observation wells. Now we have added an observation wells that we can use to evaluate our model performance.

If you select more simulation results, you will be able to analyse the behaviour of different variants of your dewatering systems.

iMOD will generate a time series for all observations which can be inspected separately in the next steps. The entered top- and bottom elevation for the observation determining what model layer need to be used to generate the time series.


Figure 11.166: Example of the Time series of the added observation and the simulated groundwater levels.


The entire project is saved in a ISF file which is easy to read and/or modify outside iMOD. Below is the example of the ISF file that we just created.

“Well Field 1”
“Well 1”,0.000,-2.500,145732.280,448621.030
“Well 2”,0.000,-2.500,145667.500,448673.470
“Well 3”,-5.000,-10.000,145608.890,448725.910
“Well 4”,-5.000,-10.000,145550.280,448778.340
“Well 5”,-15.000,-20.000,145491.690,448821.530
“Observation 1”