| Public Works Research Institute (PWRI) has been conducting a research on vulnerability assessment of levee systems using an integrated geophysical method in cooperation with Society of Exploration Geophysicists of Japan (SEGJ) since 2005, concurrently with Hurricane Katrina disaster. We successfully demonstrated that the integrated geophysical method could delineate internal complex structure in levee systems, which had been thought to have simple stacked structures. We also demonstrated the usefulness of cross-plot analysis for the classification of physical properties of levee systems. After the 2011 East Japan Earthquake, the technique has been widely applied to the levees damaged by the Earthquake. However, river engineers pointed out discrepancies between geophysical survey results and geotechnical data. To cope with this concern, SEGJ compiled both data to make comprehensive database and analyzed them statistically to propose appropriate soil physics models for the safety assessment of levees. PWRI took charge of field measurements for obtaining ground truth data and development of detailed geophysical survey methods. In this paper, the author introduce the present status of safety assessment of levee systems in Japan, and show cases of ground truthing by means of detailed geophysical methods. |
