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| | Abstract | | A small but dense integrated geophysical surveying was conducted on a levee system, part of which was to be excavated for constructing a bridge abutment. The integrated geophysics comprised two types of DC resistivity measurements, hybrid surface wave survey along a short line about 100 m set on the levee crest. Time-lapse resistivity tomography monitoring was also applied during the surface watering for the infiltration into the levee body. A total of 800 L water was seeped over 10 hours. A newly developed high-speed measurement tool was utilized to measure the resistivity and to monitor its change during the infiltration. The resistivity tomography profiles clearly delineated the infiltrated portion in the levee body and enabled to estimate permeability of vadose zone under unsaturated conditions in the field. In addition, hybrid surface wave survey, or the combination of active and passive measurements using the same geophones on the same survey line, successfully provided an S-wave velocity profile down to 30 m below the surface. |
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