Landslide susceptibility and ground displacement assessment of austin city and its surroundings

Hernandez Marin, Rosbeidy Ariana

Publication

Landslide susceptibility and ground displacement assessment of austin city and its surroundings

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Hernandez Marin, Rosbeidy Ariana

Date

2022-07-20

Abstract

Recently, the city of Austin and its suburbs have witnessed high population growth that has driven communities to reside in areas susceptible to landslide hazards. This study integrated multiple datasets using different techniques to assess the landslide hazards susceptibility in the area, as well as slow-moving slide identification areas and their displacement rate quantification. The results are: (a) a landslide susceptibility map (LSM) derived by combining six factors and variables that could influence the incidence of landslides indicates that 16.8% of the study area is highly susceptible to the hazard. These areas lie on moderate to steep slopes (> 14°) proximal to geological structures and drainage networks, have low to moderate vegetation cover, and receive moderate amounts of annual rainfall (> 870 mm). The main geologic units include the fractured and weathered limestones from the Eagle Ford, Georgetown, Buda Formations, the Del Rio Formation, and patches of gravel and terrace deposits; (b) Small Baseline Subset (SBAS) interferometric analysis technique was applied on fifty-three Sentinel-1 images, the results calibrated and validated using permanent and campaign Global Navigation Satellite System (GNSS) datasets, to detect slow-moving type landslides and quantify their rates. The results indicate that the slow-moving slides across the study area move at displacement rates ranging from -1 to -3.06 mm/yr. The analysis shows a high spatial correlation between the medium-high and high landslide susceptible areas delineated using the LSM and SBAS method in the north and northwestern parts of the study area; (c) the findings of the present study indicate that the interactions of water percolating through the fractured Buda Formation with the montmorillonite- and kaolinite-bearing Del Rio Formation resulted in a buildup of shear stress and initiated the displacement of the slope material. Intense rainfall episodes hastened the displacement rates and eventually led to slope failures. The slope failure mechanism put forward in this study was assessed through a close investigation of the Pease Park (Shoal Creek) landslide through lithologic sample analysis and a 3D model derived using data acquired using Unmanned Aerial Vehicle (UAV).