SEGJ Technical Conference


Integrated geophysical investigation along an urban river: A case study at Toyohira River.


Abstract
We conducted a feasibility study of integrated geophysical investigation along an urban river levee, crown of which is used as a two-lane trunk highway, and river-side slope is widely protected with various kinds of revetments. Capacitively coupled resistivity survey using OhmMapper, hybrid surface wave surveys including walk-around surface wave method were adopted in this study. As a result, 2D Vs and resistivity structure was clearly delineated up to 30 m below the survey line, set along a sidewalk of the trunk highway. Regretfully, limited reference information was available to interpret the study result, however the geophysical structure was consistent with ancient river geomorphology and the levee system was inferred to be safe in the view point of seepage. In the next production survey stage, survey lines are recommended to be set along a traffic lane under restriction.