ELECTROMAGNETIC INDUCTION SURVEY TO SEARCH FOR BURIED RIVER CHANNEL AT HERITAGE PARK, COLERAIN TOWNSHIP, OHIO

The Great Miami River in Hamilton County, Ohio has had several historically significant flooding events, some of which have led to channel avulsion. Historical documents suggest that the Great Miami River used to run through what is now Heritage Park until a major flood in 1959. Though the park has been filled in and leveled, the pre-flood buried river channel may still be identifiable. However, it is possible that much of the surrounding region’s subsurface is composed of older glaciofluvial deposits, which may render the channel unidentifiable. Here, we test whether the channel is identifiable by using electromagnetic induction (EMI) coupled with electrical resistivity.

We collected EMI data using a DUALEM-421 device along 19 lines (13 E-W and 6 NW-SE) spanning most of the area of the suspected buried channel (now a disc golf course). The DUALEM-421 provides conductivity data with dual geometry readings at separations of 4, 2, and 1 meters. Additionally, resistivity data were collected using a 24-electrode Syscal Kid Switch system to calibrate the depth of the EMI readings using Wenner arrays with 1, 3, and 5 m a-spacing. These data were then processed using Resipy, and forward modeling of EMI data compared with the resistivity data was used to develop models of the subsurface lithology.

From our models, we see evidence of the prior location of the Great Miami River inside the area of Heritage Park. The conductivities of layers were measured to be primarily in the range of 2-6 mS/m throughout much of the western region, with a rapid shift to the range of 6-30 mS/m throughout the eastern part of the region. The higher conductivity regions indicate less porous fine-grained sediments and organic material and the lower conductivity region indicates more porous, coarser-grained channel fill material, with the pores filled with primarily air. This may coincide with the presence of a buried river channel running between the corner and eastern section. Additionally, the low conductivity region sits within a depression noted on a topographic map from 1955. Ultimately, EMI coupled with resistivity is a valuable tool for understanding Quaternary fluvial stratigraphy.