Correlating Gpr And Resistivity Surveys With Cone Penetrometer And Shallow Coring Studies Along The Aberjona River.

A multi-modality survey using 3-D GPR and Resistivity techniques was performed to<br>assist hydrologists in characterizing groundwater flow near the Well-H region of the<br>Aberjona river in Woburn, Massachusetts. Concurrent cone penetrometer and coring<br>studies provided “ground truth” data about the stratigraphy, soil chemistry and<br>composition of the first ten meters of peat and sand. What remained for GPR and<br>resistivity was to extend such point-source ground truth information into a 3-D map of<br>the stratigraphy of the entire region by inferring soil properties from the electrical<br>measurements.<br>Electrical conductivity values were measured at some of the same points where coring<br>and cone penetrometer measurements had been made, to physically correlate electrical<br>properties with structural data collected at the same location. Conductivities at these<br>locations were also estimated independently using GPR and resistivity and then compared<br>to probe measurements.<br>EM wave velocity estimates were determined by CMP gathers which were used to infer<br>the depth to the reflective layers. A synthesis of the conductivity changes was then<br>compared to the stratigraphic surfaces detected by the resistivity and GPR surveys as well<br>as the penetrometer data. Finally, an empirical relationship between soil stratigraphy and<br>attenuation of the radar signal at these isolated locations was assembled.<br>Cone penetrometer measurements were made along two orthogonal lines against which<br>GPR surveys along the same profiles could be compared. The results show a strong<br>correlation between the probe data and the electrical measurements. By combining the<br>probe data that had been collected along these profiles with the GPR and resistivity data<br>of the area, we were then able to create a 3-D map of the subsurface properties and to<br>generate a structural interpretation of the entire region.