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Method of measurement and precautions for groundwater aeration sound

Overview of the Procedures for Measurement

With regard to a slope to be measured, determine a measurement line in the longitudinal or transversal direction.
Next, determine the intervals for measurement points that are required for the accuracy of investigation. If the intervals are too big, there may be deviation from a groundwater path (recommended value: at intervals of 2 – 10 m).
Write down the place, measurement line number, intervals for measurement points, etc. and when preparations for the entry of groundwater aeration sound have been made, start measurement by following the procedures described below.

[Prior preparation]
Assemble the device.

[Fixation of the sensor]
Insert the pickup sensor into the ground.
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[Adjustment of the degree of amplification]
Turn on power and adjust the degree of amplification so that the groundwater aeration sound has appropriate loudness by means of the switch for ◀(decrease) or ▶(increase).
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[Filter settings]
Look for settings for the frequency filters with which the sound can easily be heard by changing the ▲ (low band) or ▼ (high band) switch. When a frequency at which where groundwater aeration sound can be heard easily, record the settings by pressing the SET button (for the combination of frequency filters, refer to the "Overview of the Mechanism of Picking Out the Groundwater Aeration Sound – On Filters."
* Once settings for the filters have been made, do not change the settings until measurement is finished.
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[Data recording]
Record the groundwater aeration sound by pressing the RECORD switch. If measurement is to be made on the same measurement line, it is recommended that measurement be made with the same setting values.
* During the recording of groundwater aeration sound, attention should be given so that no sound is given off in the surrounding areas or no vibration is given to the ground.
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[Record of the result of measurement]
After completion of the recording of groundwater aeration sound, the measurement point, typical value (*D) of the result of calculation, and record number are recorded in a field book.
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[End of measurement]
Turn off power for the measurement recording unit, and pull out the pickup sensor from the ground.

[Record of the position of measurement]
Using the GPS terminal, put the latitude and longitude of the measurement point (use of the average position measurement mode is recommended), and fill out the field book with the position number.
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Move to the next measurement point.

Grasping the outline of landform

Assembly of the device

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