Advances in tensiometry for long-term monitoring of soil water pressures

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doi: 10.2113/1.2.310
Authors:Sisson, J. B.; Gee, G. W.; Hubbell, J. M.; Bratton, W. L.; Ritter, J. C.; Ward, A. L.; Caldwell, T. G.
Author Affiliations:Primary:
Bechtel Idaho, Geosciences Research Department, Idaho Falls, ID, United States
Pacific Northwest National Laboratory, United States
Applied Research Associates, United States
Desert Research Institute, United States
Volume Title:Vadose Zone Journal
Source:Vadose Zone Journal, 1(2), p.310-315. Publisher: Soil Science Society of America, Madison, WI, United States. ISSN: 1539-1663
Publication Date:2002
Note:In English. Accessed on December 16, 2005. 13 refs.; illus.
Summary:Soil water pressures, measured over space and time, are needed to predict the direction of water flow and chemical transport in the vadose zone. Advanced tensiometers (ATs), which utilize a water-filled porous cup connected directly to a pressure transducer, can be installed at almost any location and depth using standard drilling techniques such as auger drilling, but these methods can significantly disturb the site. For sites where minimal disturbance is desired, alternate approaches for tensiometer placement have been sought. To test installation techniques and performance longevity, advanced tensiometers were placed into the ground at a test site near Richland, WA using two different installation methods, auger drilling and a drive-cone push technique. The tensiometers were subsequently monitored for nearly 2 yr without refilling or recalibration. The data indicated that tensiometers placed by the auger technique took several months to equilibrate, while the cone push units came to equilibrium within 24 h following their installation. Soil water pressures always remained above -90 cm pressure head (-90 mbar) at depths >90 cm. At the greatest depth (730 cm), positive then negative pressures were observed as the water table was lowered and the soil drained. The results suggest that for our test conditions (coarse sandy soil, no vegetation), soil water pressures stay well within the tensiometer range and unit gradient conditions persist, indicating a draining profile. Advanced tensiometers, placed either by auger or cone penetrometer, provide a robust and reliable method for long-term monitoring of soil water pressure profiles.
Subjects:Chlorinated hydrocarbons; Clastic sediments; Experimental studies; Field studies; Halogenated hydrocarbons; In situ; Instruments; Lysimeters; Moisture; Monitoring; Organic compounds; Pollutants; Sand; Sediments; Soils; Techniques; Tensiometers; Unsaturated zone; Vinyl chloride; Water pressure; Benton County Washington; Columbia Plateau; Richland Washington; United States; Washington; Drive cone method; Hollow-stem auger method
Coordinates:N461700 N461700 W1191700 W1191700
Record ID:2006007769
Copyright Information:GeoRef, Copyright 2018 American Geosciences Institute.
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