Shrinking salt crusts of the Bonneville Basin, Utah: Observations from multispectral remote sensing

Halite crusts in Utah's Bonneville basin, including the Bonneville Salt Flats, Newfoundland basin, and Pilot Valley saline pans, show rapid spatiotemporal variations and significant declines in surface area over the past century. Using multispectral satellite imagery from 1984 to 2024 (585 dates), aerial imagery from 1946 to 1978, and a 1925 map, we analyze long-term changes in halite and water surface areas to understand these salt crust systems' evolution and hydrological/climatic influences. Data are processed into Normalized Difference Water Index and Halite Index rasters and classified with static and dynamic thresholds, respectively. Results indicate that the Bonneville Salt Flats has shrunk by 75 % since 1925, with a decline rate of 0.75–1.45 km 2 /year, projecting a potential disappearance between 2072 and 2126. The Newfoundland basin crust, an anthropogenic feature, has been declining at 2.6–6 km 2 /year and may vanish between 2154 and 2353. When normalized to initial area, decline rates are comparable between the Bonneville Salt Flats and Newfoundland basin. In contrast, the ephemeral Pilot Valley crust shows no clear long-term reduction in area but considerable intra-annual variability. Flooding events are observed to be significant drivers of halite area changes, with post-flood halite growth 30–90 days after peak water area. These findings underscore the dynamic nature of salt crust systems, reveal links between hydrological cycles and crust dynamics, and provide a framework for future research, monitoring, and management of salt flats in arid regions. • Bonneville Salt Flats area shrank by ~75 % since 1925, with annual loss ongoing. • Newfoundland basin salt crust, formed in the 1980s, is shrinking at 6 km 2 per year. • Pilot Valley shows large yearly halite changes but no long-term decline trend. • Flooding events drive seasonal halite area growth across all saline pans studied. • Provides a framework for analyzing salt crust dynamics and hydrological impacts.