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Monitoring Moisture Migration in the Vadose Zone with Resistivity
Author(s) -
Kean William F.,
Waller Muriel Jennings,
Layson H. Richard
Publication year - 1987
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/j.1745-6584.1987.tb02886.x
Subject(s) - vadose zone , water content , silt , moisture , soil water , geology , soil science , electrical resistivity and conductivity , gravimetric analysis , water table , hydrology (agriculture) , mineralogy , geotechnical engineering , groundwater , geomorphology , materials science , composite material , chemistry , engineering , organic chemistry , electrical engineering
Studies of moisture migration in the vadose zone were conducted at four field sites using a reverse Schlumberger resistivity array. Gravimetric moisture measurements on soil samples taken at each of the field sites were made to a maximum depth of 1.83 meters, and these results were correlated with resistivity values. Tensiometer measurements were also taken at two of the four sites. The soils at the sites have combined clay and silt content (less than .0625 mm grain size) which varies from 13% to 84%. Three of the sites are underlain by sand or gravel in the unsaturated zone. The fourth site has fractured but relatively impermeable shales and siltstones under the surface soils. Depths to water table varied from 1.58 m to 13.7 m. Resistivity and gravimetric moisture measurements were carried out prior to the addition of water to the surface, and following the application of water, either by watering of the site (at two sites) or during and after rainfall events (at two sites). Monitoring was carried out for periods of one to three weeks. Results indicate that (1) moisture is retained for long periods of time in clay/silt‐rich soils; (2) moisture migration is slow below a moist soil zone and is not readily detected by surface resistivity measurements; and (3) near‐surface moisture changes can be defined by surface resistivity.