Exercise 2: Leaky Aquifer - Hantush - Jacob Analysis

This exercise demonstrates analysis of a leaky aquifer based on the pumping test data published in Dawson and Istok (1991), p. 113.

Create the Pumping Test and Enter the Data

To create a new Pumping test project:

[1] Launch AquiferTest and from the Welcome screen, ensuring that the "Create Pumping Test" box is checked, choose the "Create a new project" button.
If you already have AquiferTest open, create a new project by clicking the (New) button from the toolbar, or select File > New from the main menu.

[2] In the Pumping Test tab, enter the following information in the appropriate fields:

Project Information frame:

•Project Name: Exercise 2

•Project No.: 2

•Client: ABC

•Location: Your Town

Pumping Test frame:

•Name: Hantush-Jacob Analysis

•Performed by: Your Name

•Date: fills in automatically

Units frame:

•Site Plan: ft

•Dimensions: ft

•Time: min

•Discharge: US gal/min

•Transmissivity: US gal/d-ft

•Pressure: mbar

Aquifer Properties frame:

•Thickness: 20

•Type: Leaky

•Bar. Eff.: leave blank

Your fields should now look similar to the figure below:

[3] In the Wells tab, a pumping well has been created by default. Set the parameters for that well as follows:

•Name: PW

•Type: Pumping Well

•X: 0

•Y: 0

[4] Create another well by clicking the Click here to create a new well link under the first well

[5] Set the parameters for the new well as follows:

•Name: OW1

•Type: Observation Well

•X: 80

•Y: 0

Your Wells grid should now look similar to the following figure:

[6] Click on the Discharge tab to enter discharge data for the pumping well

[7] In the Discharge frame select the radio button beside “Constant”

[8] Enter 70 in the field to the right.

[9] Click the Water Levels tab to enter the water level data for the observation well. In this example you will cut-and-paste data from a data file.

[10] In the window in the top left corner highlight “OW1”

[11] Minimize AquiferTest, and browse to the folder
"C:\Users\Public\Documents\AquiferTest Pro\Exercises\SupportingFiles\" and select the file Exercise 2.xls.

[12] Double-click on this file, to open it in MS-Excel

[13] Select the first two columns of data (numbers only), and Copy this onto the Windows clipboard

[14] Minimize MS-Excel and Maximize the AquiferTest window

[15] Activate the Water Levels tab

[16] Right-click on the first cell in the Time Water Level grid, and select Paste

[17] Enter 0 in the Static Water Level field.

[18] The calculated drawdown appears in the Drawdown column and a graph of the drawdown appears to the right of the data.

The water drawdown graph should now look similar to the following figure:

If the graph is blank, click the Refresh button in the main toolbar to refresh the graph.

[19] Click on the Analysis tab

[20] Check the box beside OW1 in the Data from window.

[21] Click the Apply Graph Settings button and select Linear from the menu that appears.

The analysis graph should now look similar to the following figure:

If you are not sure whether the aquifer is leaky or not, you can use the Diagnostic Plots, and analyze the drawdown derivative data, to provide insight on the pumping test activities. This is demonstrated below.

Interpreting the Pumping Test Data with Derivative Analysis

In this section of the Exercise, you will use the advanced features of AquiferTest Pro to perform a derivative analysis and compare the results to the diagnostic plots to update the analytical based on your findings.

NOTE: The functionality and steps described below are not available in the Standard Edition of AquiferTest. If you are using the Standard Edition of AquiferTest, you may read this section for reference or skip ahead to the next section: Pumping Test Analysis - Hantush-Jacob.

[21] Click on the Diagnostic Graph tab in the Analysis plot.

[22] Press the lin-log radio button above the diagnostic graphs. The diagnostic graph should appear similar to the following image:

In this image, you can see the observed drawdown data, and the calculated derivative data. The derivative data is distinguished by an X through the middle of each data symbol, and is delineated in the image above.

To the right of the graph window, you will see six diagnostic plot windows, with a variety of type curves. The plots are named diagnostic, since they provide an insight or “diagnosis” of the aquifer type and conditions. Each plot contains theoretical drawdown curves for a variety of aquifer conditions, well effects, and boundary influences, which include:

•Confined

•Leaky

•Recharge Boundary

•Barrier Boundary

•Unconfined or Double Porosity

•Well Effects

Each diagnostic graph contains 2 lines:

•Type curve (blue solid line)

•Derivative of type curve (dotted line)

If you look at the derivative data in the Diagnostic Graph, you can see the characteristic “saddle”, typical of a leaky aquifer (outlined in the image above). Alternately, you can use the semi-log diagnostic graph to interpret the aquifer conditions.

In the Semi-Log plot, you can compare the observed drawdown curve to the diagnostic plots. In this example, it is evident that the observed drawdown curve is very similar to the characteristic "saddle" curve expected in a Leaky aquifer (refer to the theoretical drawdown curve in the second diagnostic graph, circled above).

For more details on the diagnostic graphs, see Diagnostic Plots.

Now that you are confident that the aquifer is leaky, you can select the appropriate solution method, and calculate the aquifer parameters.

Pumping Test Analysis - Hantush-Jacob

In this section of the Exercise, you will create a new analysis using the Hantush-Jacob (1955) method, which accounts for vertical leakage through an adjacent aquitard, based on the derivative analysis and interpretation you preformed in the previous section of this tutorial.

[23] Click on the Analysis Graph tab

[24] Select “Hantush” from the Analysis methods frame of the Analysis navigator panel

[25] In the Analysis Name field enter “Hantush-Jacob”

[26] Click on the (Fit) icon, to fit the data to the type curve. The analysis graph should appear similar to below:

[27] If you are not satisfied with the fit, use the Parameter Controls to adjust the curve:

To view the Dimensionless (Type Curve) view, click the Dimensionless button above the analysis plot.

[27] Click the Dimensionless button once, resulting in the following dimensionless analysis graph:

[28] The Results frame of the Analysis navigator displays the calculated values. These values should be approximately:

•Transmissivity (T) = 4.20E3 US gal/d-ft

•Storativity (S) = 9.97E-5

•Hydraulic resistance (c) = 2.85E4 min

The following table illustrates a comparison of these values with those published.

Printing the Report

In this section of the Exercise, you will print the report of your analysis.

[29] To print your report, click on the Reports tab

[30] Expand the Navigator tree in the left portion of the Reports tab

[31] Check the box beside the “Hantush-Jacob” under Analysis Graphs

NOTE: You can add your company information and logo to the space in the upper left of the report page(s) by selecting Tools > Options from the main menu and adjusting the settings in the Reports tab.

[32] Click on the (Print) button in the tool bar, or select File> Print from the main menu.

[33] Save your project by selecting File > Save As, and define a project name (e.g. Example 2.HYT).

The next exercise will demonstrate analysis of recovery data from a pumping test, using the Agarwal solution. You have the option to exit the program or to continue on to the next exercise.

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