Detecting a Buried Log Flume and Canals in Eau Claire, Wisconsin: A Geophysical Investigation of the Subsurface

Keywords: ground penetrating radar, log flume, canal detection, tunnel detection
Abstract Type: Poster Abstract

Abstract

In the nineteenth century, the lumber industry was the impetus for western Wisconsin’s development. Lumber was transported from forests to processing facilities via rivers. Humanmade waterways, such as canals and log flumes were built to connect rivers with processing facilities. In Eau Claire, Wisconsin, where canals and a log flume were built to connect the Chippewa River to Half Moon Lake. Little evidence of the flume ditches, flume tunnel, and canals are present above ground as they have been filled. Flume tunnel, flume ditch, and canal locations were identified through archival research, georectification of historical maps, and aerial photos.
Studies have shown that ground penetrating radar (GPR) is a viable method for locating tunnels and ditches. GPR is a non-invasive subsurface imaging method which utilizes electromagnetic pulses and their reflections. GPR was chosen to corroborate flume and canal locations in the subsurface based on historical maps and aerial photos. Data was collected using a pulseEKKO Pro GPR system, with 100MHz antennae. Data was collected in reflection survey mode, with a 500ns time window, and a 0.25m step size. GPR transects were topographically corrected with 1m interval data collected using a
Topcon RL-H4C laser level. Data was processed with EKKO_Project V5 and pulseEKKO IV software. GPR data was interpreted with considerations for land use changes over time alongside maps and aerial imagery. Georectified maps show the paths of the flume and canals. GPR data
corroborates the location of the canal and indicates possible presence of the flume tunnel in studied area.