InSAR techniques in site-application: Mapping ground deformation at Last Chance Grade using Sentinel 1-A interferometric data

Abstract

Last Chance Grade (LCG) is a project to study solutions to a historically unstable 3-mile stretch of US Highway 101. The California Department of Transportation (Caltrans) and associated partners are considering several alternatives to reroute highway traffic, including tunnelling, inland rerouting, and the development of resilient structures and drainage systems. Interferometric Synthetic Aperture Radar (InSAR) is a sensing technique that allows for the monitoring of small changes in surface deformation over small- and large-time scales. The goal of this thesis is to apply InSAR analysis to the LCG site and evaluate current proposals based on observable ground-deformation patterns. To this end, I compiled and built from Open-Source code the InSAR Scientific Computing environment and ran time-series analysis of ground deformation using data from the European Space Agency’s Copernicus Open Access Hub. For greater accuracy and clarity, the data was corrected for ionospheric interference, and the interferograms were unwrapped using the snaphu algorithm so that the phase band could be interpreted. The resulting products were geocoded and exported for visualization in QGIS. From these images deformation trends of the area are observed and qualitative analysis is performed with regards to how observable trends intersect with potential alternate solutions to transportation rerouting.