Brenda Beitler Bowen

The Bonneville Salt Flats (BSF) in northwestern Utah, USA, has experienced changes in area, thickness, and hydrology over the past century. This study investigates the relationship between multispectral Halite Index (HI) values, which are sensitive to halite moisture content, from Landsat and Sentinel‐2 imagery and groundwater depth (GWD) measured by nine piezometers, based on the principle that surface moisture in the halite crust is driven primarily by depth of groundwater and secondarily by atmospheric precipitation or humidity. Linear regressions reveal moderately strong correlations, and regression coefficients are used to calibrate HI values to GWD. Satellite‐calibrated GWD time series show temporal alignment with piezometer records, with a median absolute deviation less than 15 cm for seven of the nine piezometers. Spatial interpolations of regression coefficients are used to calibrate HI imagery to GWD imagery, highlighting the groundwater table's spatiotemporal variability and relation to climate. Groundwater depth is observed to be very sensitive to climatic conditions, as GWD across the crust scales with Palmer Drought Severity Index data. The methodology is tested for available piezometer data at the Badwater Basin, Salar de Uyuni, and Salar de Atacama to explore global applicability. The results from this study confirm the potential of multispectral remote sensing for monitoring GWD at the BSF and suggest the methodology could be transferable to similar salt crusts globally.

As a result of drought and consumptive water use, reservoirs worldwide are experiencing declines in storage. The landscapes exposed by falling water levels may be colonized by novel vegetation communities in terms of species composition and succession, and/or reworked by geomorphic processes at sub‐annual to decadal timescales. Despite research on the response of downstream rivers to dam and reservoir operations, we know surprisingly little regarding the eco‐geomorphic processes that shape backwaters upstream of reservoirs. Here we use a decadal‐scale record of aerial imagery and support vector machine learning to classify land cover change along more than 140 km of the Colorado and San Juan Rivers within Lake Powell Reservoir in Utah. Our results reveal a consistent trajectory of land cover change, wherein declining water levels expose bare sediment, which is subsequently colonized by vegetation. With continued water level declines, vegetation exhibits defoliation consistent with water stress. Similar patterns of landscape evolution were observed with regard to exposure age of formerly inundated surfaces on both rivers, wherein older surfaces were marked by bare sediment and/or stressed vegetation. Divergence in response to reservoir drawdown was observed with regard to the downstream propagation rate of land cover changes. Specifically, on the steep‐and‐narrow Colorado River, the trajectory of bare sediment to green vegetation to stressed vegetation occurred more rapidly as water levels declined than on the San Juan River. The observations detailed here may guide reservoir management to promote recruitment of desirable land cover types (e.g., native and/or complex ecosystems) under shifting water supply.

The Bonneville Salt Flats, a landscape characterized by a perennial halite crust and seasonal flooding in western Utah, USA, provides a natural laboratory for advancing understanding of the processes that create and change dynamic saline environments. A decade of interdisciplinary research on the Bonneville Salt Flats has resulted in a new understanding of the salt's history, the functioning of the salt crust ecosystem, and the role that humans play in shaping this landscape. Sedimentological analyses of cores collected across the salt has changed our understanding of the history of the landscape, including evidence of extensive erosion after Pleistocene Lake Bonneville, the surprisingly young age of the oldest salt (~5.4 cal ka BP), and historical and ongoing crust halite dissolution. 16S rRNA gene and metagenomic analysis of the salt crust reveals a complex and robust microbial and archaeal ecosystem within the salt, hosting a wide range of metabolic pathways that actively cycle C, N, and S through the landscape. A long-term environmental observation station established at the center of the salt crust provides a robust new record of landscape processes, weather data, and eddy covariance flux measurements that have helped to constrain the energy and water budgets and highlight the sensitivity of ecosystem-scale surface conductance in the absence of vegetation to atmospheric drying. Arial and spaceborne remote sensing data show the impacts of over a century of human activities on landscape composition and texture, including groundwater extraction for potash mining, intensive surface modification, and land use associated with high-speed vehicle racing on the salt. Brine extraction and attempted mitigation have resulted in salinity and salt crust extent decreases over the last several decades, potentially limiting future landscape uses. The intricate interconnection of the human-natural system has enabled the exploration of variations in mental models influencing decision-making, attribution of blame, and the feasibility of adaptive management in dynamic landscapes serving diverse and conflicting needs. Integration of science with art has expanded the nature of the inquiry and led to new ways of thinking about human connections to a seemingly barren, but truly alive, place. All of these new insights into saline landscapes and the role that human land use and climate change play in altering processes are significant to understand as water delivered to closed basin saline lakes globally is in decline, potentially leading to an expansion of exposed salt-encrusted landscapes.

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 meters and temporal baselines of 12, 24, and 36 days, were analyzed using spatially and temporally reduced statistics, along with median absolute deviation 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 & racing), highlighting the relative impact of land-use activities on the salt crust. Coherence observations indicate 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.

The depositional history of the Bonneville Salt Flats, a perennial saline pan in Utah's Bonneville basin, has poor temporal constraints, and the climatic and geomorphic conditions that led to saline pan formation there are poorly understood. We explore the late Pleistocene to Holocene depositional record of Bonneville Salt Flats cores. Our data challenge the assumption that the saline pan formed from the desiccation of Lake Bonneville, the largest late Pleistocene lake in the Great Basin, which covered this area from 30 to 13 cal ka BP. We test two hypotheses: whether climatic transitions from (1) wet to arid or (2) arid to wet led to saline pan deposition. We describe the depositional record with radiocarbon dating, sedimentological structures, mineralogy, diatom, ostracode, and portable X-ray fluorescence spectrometer measurements. Gypsum and carbonate strontium isotope ratio measurements reflect changes in water sources. Three shallow saline lake to desiccation cycles occurred from >45 and >28 cal ka BP. Deflation removed Lake Bonneville sediments between 13 and 8.3 cal ka BP. Gypsum deposition spanned 8.3 to 5.4 cal ka BP, while the oldest halite interval formed from 5.4 to 3.5 cal ka BP during a wetter period. These findings offer valuable insights for sedimentologists, archaeologists, geomorphologists, and land managers.

Evaporated: Explorations in Art, Science, and Salt was a collaborative art exhibition that included sculptures, photographs, video, sound, and drawing, integrated with scientific data displays that encouraged the viewer to ponder the complexity of the Bonneville Salt Flats and our relationships to the landscape. This experimental exhibition was one of the outcomes from a five-year collaboration between geoscientist Brenda Bowen and artist Wendy Wischer exploring the rapidly changing Bonneville Salt Flats in northwest Utah through the lenses of both art and science. Evaporated provided an opportunity for both scholars to experiment with different ways of sharing their research, scholarly and creative, in the hopes of promoting understanding of the connections and differences between visual art and geoscience in academic contexts.

Acid-saline sediments in shallow-lake environments in southwestern Australia host complex mineralogical suites representing long-term weathering and modern extreme acid saline chemistry. It is not known whether large-scale reflectance spectroscopy datasets from watersheds across the Yilgarn Craton show regional mineralogical variability. This study assesses over 2,500 spectra from datasets of shallow subsurface sediments by using automatic minima detections for spectral features of interest. Integrating microscopic and spectral observations show that proportionally similar mineral assemblages exist in a variety of recognizable textures. Spectral results indicate iron oxide and phyllosilicates are the most detected mineral types, alongside less common alunite, jarosite, and gypsum. The difference in detection abundance by percentage for mineral groups, particularly iron oxides, accounts for the largest regional variation observed in spectra. Spectral feature characteristics show significant regional variation for iron oxide, alunite, and hydrated mineral absorptions. The spectral observations align with previous mineralogical observations of these landscapes and the expected weathering evolution for granitoids, where Al-phyllosilicates and iron oxides are most prevalent. Observations of these mineral suites enhance understanding of regional differences and similarities in chemical precipitates and products of water-rock interaction in extreme acid-saline environments and have implications for studying sediments and rocks on Mars.

The Bonneville Salt Flats, Utah, is a managed landscape with a history of potas...

Fractured rock aquifers cover much of Earth's surface and are important mountain sites for groundwater recharge but are poorly understood. To investigate groundwater systematics of a fractured‐dominated aquifer in Baja California Sur, Mexico, we examined the spatial patterns of aquifer recharge and connectivity using the geochemistry of springs. We evaluate a range of geochemical data within the context of two endmember hypotheses describing spatial recharge patterns and fracture connectivity. Hypothesis 1 is that the aquifer system is segmented, and springs are fed by local recharge. Hypothesis 2 is that the aquifer system is well connected, with dominant recharge occurring in the higher elevations. The study site is a small 2 catchment. Thirty‐four distinct springs and two wells were identified in the study area, and 24 of these sites were sampled for geochemical analyses along an elevation gradient and canyon transect. These analyses included major ion composition, trace element and strontium isotopes, δ ¹⁸ O and δ ² H isotopes, radiocarbon, and tritium. δ ¹⁸ O and δ ² H isotopes suggest that the precipitation feeding the groundwater system has at least two distinct sources. Carbon isotopes showed a change along the canyon transect, suggesting that shorter flowpaths feed springs in the top of the transect, and longer flowpaths discharge near the bottom. Geochemical interpretations support a combination of the two proposed hypotheses. Understanding of the connectivity and provenance of these springs is significant as they are the primary source of water for the communities that inhabit this region and may be impacted by changes in recharge and use.