Comparative study of seismic techniques (refraction, SASW and borehole) for determining the depth and position of the water table in the vicinity of the Rio Grande
I conducted a comparison study to detect the seasonal changes in position of the water table depth using seismic refraction, Spectral Analysis of Surface Waves (SASW), down hole seismic and DC resistivity geophysical techniques in two silty sand areas in the vicinity of the Rio Grande (Feb 2002, June 2002 and March 2003). These areas contain slightly silty sand and friable silty clay loam, and are located near two sets of boreholes (∼200 meters apart) within the Rio Bosque Park. ^ The seasonal fluctuation of the water table depth is a function of the amount of rain, irrigation and river levels. A combination of four geophysical surveys is used to establish a correlation between the water table depth as measured in boreholes and its various geophysical signatures. To establish the reliability of the geophysical techniques, I conducted several experiments in both the laboratory and the field to verify the velocity profiles of dry and saturated materials at the two sites. ^ The downhole seismic, SASW and DC resistivity techniques all provided three-layer soil models with layer thicknesses and properties consistent with the known depth to the water table. The seismic refraction technique, however, overestimates the water table depth by three factors. The SASW method appears to be the best technique for locating the water table, with estimates within ∼20 cm of true water table depth. ^
"Comparative study of seismic techniques (refraction, SASW and borehole) for determining the depth and position of the water table in the vicinity of the Rio Grande"
(January 1, 2003).
ETD Collection for University of Texas, El Paso.