Fig. 3. (a) Two-dimensional volumetric water content tomogram for the saturated zone, calculated from the interwell velocity tomogram and the Burggeman–Hanai–Sen mixing formula (Sen et al., 1981; Feng and Sen, 1985). The white Xs indicate the transmitter and receiver station locations. (b) Measured water content () variation vs. depth between the two boreholes on the right side of the section. In the saturated zone, the water content is equal to the porosity (). Above the water table, the porosity was measured in the laboratory on cores collected during drilling. The locations and measured values of the porosity are indicated by filled circles.