Residential Property Annual Slope Movement Monitoring in Erwin, Tennessee

Harris, Sarah, East Tennessee State University, Department of Geosciences, harrissl1@etsu.edu; Michael Whitelaw, whitelaw@etsu.edu; Arpita Nandi, nandi@etsu.edu (Poster)

Mass movements are a constant threat in the mountains of East Tennessee. This study reports on a monitoring project conducted on a residential property located on an active hillslope with three documented mudslide events since 2012, the latest on April 13, 2020. The property is located at the toe of Looking Glass Mountain, Erwin, Tennessee, and has multiple risk factors that suggests further movement is likely. The house is placed on a thin, 3 m alluvial conglomerate which overlies the Buffalo Mountain thrust and well-bedded phyllitic dolomites that both dip subparallel to the 25-ft hillslope. The house foundation and driveway sit 20 miles above an access road that parallels Little Indian Creek. The slope immediately below the house has been over-steepened to 50 feet by construction of the access road and further destabilized by poorly directed drainage from the house roof and removal of vegetation to enable a view of the creek. In order to monitor slope motion a grid of 43 steel pins was placed along the driveway, below the house, and at the access road entrance. All sites were surveyed with a laser range finder every two weeks from June 2019 to April 2020. Rainfall data was collected to allow comparison between rainfall events and slope movement. An Unmanned Aerial Vehicle (UAV) was used to provide photogrammetry of the site to better characterize slope topography and drainage and to document the April 2020 event. Pin survey data indicates that there was an average of 0.153 m of downslope motion between June 2019 and March 2020 indicating soil creep, which mobilized into a mudslide on April 13, 2020, at the property’s access road entrance. The slope movement at the site is significantly positively correlated (r = 0.69 at p < 0.05) with regional rainfall accumulation.

Bio:

My name is Sarah Harris. I’m a senior at East Tennessee State University in Johnson City, Tennessee. I will graduate in December 2020 with a Bachelor’s degree in Geosciences with a concentration in Geology and Environment and a minor in GIS. I currently live in Southwest Virginia. I have a 12 year old son named Zack who is my biggest supporter.

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