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Exercise 2: Leaky Aquifer - Hantush - Jacob Analysis

This exercise is written with the assumption that you have gone through the first exercise, and are familiar with the AquiferTest interface.

This exercise is based on the pumping test data published in Dawson and Istok (1991), p. 113

[1] Launch AquiferTest and from the landing page ensure that the "Create Pumping Test" box is checked and 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:

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\Supporting Files\" 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] Click on the (Refresh) button in the toolbar, to refresh the graph. 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:

[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.

[21] Click on the Diagnostic Graph tab in the Analysis plot, and the following window will appear:

 

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 6 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)

These plots can be displayed on a log-log or semi-log (lin-log) scale, by selecting the appropriate radio button above the diagnostic graphs. For this example, the aquifer type is not immediately evident upon inspection of only the drawdown data. However, if you look at the derivative data, 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.

 

[22] Press the lin-log radio button above the diagnostic graphs. The following window will appear.

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 (outlined in the image above) is very similar to that expected in a Leaky aquifer (refer to the theoretical drawdown curve in the second diagnostic graph, circled above).

NOTE: the red trend line for the drawdown derivatives has been drawn on top of this figure by hand for illustration purposes

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.

[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 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 = 4.20E3 US gal/d-ft

Storativity = 9.97E-5

Hydraulic resistance = 2.85E4 min

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

 

AquiferTest

Published
(Dawson, 1991)

Transmissivity (US gal/d-ft)

4.20 E3

4.11 E3

Storativity (-)

9.97 E-5

9.50 E-6

 

[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 define your company information and logo under Tools/Options.

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

[33] Save your project by clicking on the (Save) icon or selecting File/Save as

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 (make sure you save the changes) or to continue on to the next exercise.

 

 

 


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