Assessing C-Band InSAR Coherence Data to Monitor Landscape Change at the Bonneville Salt Flats, Utah

The Bonneville Salt Flats (BSF) of Utah, with a notable history in land-speed racing and resource extraction, presents a dynamic landscape shaped by both natural processes and anthropogenic activities. This study leverages interferometric synthetic aperture radar (InSAR) techniques to monitor the BSF, focusing on the potential of coherence as an indicator of surface changes. A total of 165 Sentinel-1 A&B coherence images, with perpendicular baselines under 100 m and temporal baselines of 12, 24, and 36 days, were analyzed using spatially and temporally reduced statistics, along with median absolute deviation (MAD) variance. The findings demonstrate consistently high coherence (>0.90) during dry conditions, contrasted by significantly lower coherence (<0.40) during periods of precipitation and flooding. Coherence showed moderate reduction (<0.70) in zones of recreational activities (driving and racing), highlighting the relative impact of land-use activities on the salt crust. Coherence observations indicate a minimal difference during periods overlapping with and following official racing events compared to periods of racetrack preparation and general recreational use. Zones with the highest variability are linked to disturbances from recreation and resource extraction, while areas with minimal variability correspond to regions with thicker halite crust. The data also revealed that large precipitation events significantly influence coherence, with a clear power-law decrease in mean coherence as precipitation and floodwater accumulation increased. This research not only validates the use of coherence for monitoring environmental evolution and the influences of anthropogenic activities at the BSF but also supports the potential of future InSAR applications for accurate phase assessments during dry periods.