| Integrated geophysical surveying has been playing an important role for the vulnerability assessment of levee systems in Japan. Actually, the surveying has been applied to a total of 700 km long levee sections, including 150 km long urgent safety surveys to the levees attacked by the 2011 East Japan Earthquake in Kanto Plain, and 50 km long research phase surveying conducted by the author. Whereas we demonstrated the usefulness of the geophysical method, river engineers or governmental river administrators still have casted a suspicious glance to the integrated geophysics. Regretfully, near-surface geophysicists in Japan are not successful in removing their misunderstanding too. Their distrust might have resulted from inconsistency between geophysical survey results with existing geotechnical information. Repeated discussions with geotechnical engineers, across geophysical survey profiles and inferred geotechnical sections, unearthed the difference in making 2D or 3D models from the field data. It is essential to emphasize that only near-surface geophysics can provide continuous 2D or 3D information of levee systems which inherently imply small-scaled heterogeneity. |
