UTILIZATION OF INTEGRATED GEOPHYSICAL INVESTIGATION FOR THE SAFETY ASSESSMENT OF LEVEE SYSTEMS

Abstract

Conventional safety assessment of levee systems usually starts from the behavioral segmentation of levee based on the damage events during past floods. Internal heterogeneity along levee body has been rarely taken into account in the segmentation process whereas the heterogeneity and resultant weak zones in physical properties are the major vulnerability factors. It was because of its difficulty in imaging levee body as well as underlying layers at low cost and high performance. It has been therefore required to develop an effective, inexpensive and easy-to-apply field survey method which enables to delineate the internal structure of levee body and underlying layers continuously. Geophysical methods are expected to play an important role in levee assessments. We tested combined geophysical methods at actual levees, and confirmed the advantages of the methods in field work, the resultant cost effectiveness, and their capability in detecting anomalies. We successfully identified anomaly structures in and beneath the levee.