| Autor: |
J. B. Sisson, J. M. Hubbell |
| Rok vydání: |
1996 |
| Předmět: |
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| Zdroj: |
Soil Science. 161:376-381 |
| ISSN: |
0038-075X |
| Popis: |
Quantifying the direction and rate of soil water movement beneath landfill disposal areas requires tensiometers capable of monitoring soil water potentials from one to several hundred meters below land surface. This paper describes a new way to use tensiometers to measure soil water potentials at nearly any depth. Two portable tensiometers were constructed and tested in the field. One portable tensiometer was sealed with a septum stopper, lowered to the bottom of a borehole, allowed to equilibrate, and retrieved to land surface. The soil water potentials were then determined through the septum stopper using a pressure transducer equipped with a hypodermic needle. A second portable tensiometer was constructed with an electronic pressure transducer with leads brought to land surface to allow continuous monitoring of soil water potentials without removing the tensiometer from the borehole for extended time periods. The portable tensiometers are retrieved to land surface periodically to refill with de-aired water. Both portable tensiometers were operated in the field with little maintenance for periods exceeding 2 months at depths of 4 to 6 meters. The response time of the portable tensiometers ranged from a few hours to several days and was limited by the contact between the porous cup and the soil. The slow response time was not found to be a serious problem in deep boreholes. The nearly constant temperature conditions found in deep boreholes were found to contribute to stable, long-term tension values and to reducing maintenance normally required by standard tensiometers. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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