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Coastal flooding transforms barrier island morphology and rapidly salinizes freshwater lenses that support island populations and ecosystems. Climate change is expected to increase coastal flood risks, and understanding future island vulnerability requires understanding erosion and salinization processes and their feedbacks. This study investigates how island morphology and groundwater salinity distributions on Hog Island, Prince Edward Island, Canada, responded to high water levels during post-tropical storm Fiona (24 September 2022), the costliest hurricane to make landfall in Canadian history. Island morphology was monitored with drone-based LiDAR, and beach groundwater dynamics were investigated with frequencydomain electromagnetic geophysics surveys and monitoring wells. Comparing pre-storm and post-disturbance data revealed high dune scarping that thinned the ocean-side foredune by 12.3 m on average and reduced the total island volume by 12%. Beach groundwater levels and electrical conductivity increased by up to 2 m and 19 mS cm 1, respectively, and the freshwater lens was lost under the eroded foredune. Measurements 9 months after the storm revealed early-stage recovery of the foredune; however, high dune scarping prolonged recovery, and the island volume only increased by 1%. Without a stable ocean-side foredune, the landward extent of recurring coastal flooding increased and limited freshwater flushing and aquifer recovery. Results indicate that rapid erosion from extreme coastal storms shifts coastal boundaries, salinizes formerly freshwater resources, and limits freshwater recovery. These findings emphasize the importance of understanding the often-overlooked interconnections between coastal flooding, erosion, and groundwater salinization to effectively manage coastal resources in an age of environmental change. Plain Language Summary Rising sea levels and more frequent storm surges will increase coastal flooding events that erode barrier island coastlines and salinize fresh groundwater. This poses a risk to economic assets, ecosystems, and potable water resources along island coasts. This study monitored changes in shoreline position and groundwater salinity following a tropical cyclone that impacted a barrier island in Prince Edward Island, Canada. Results show that high water levels and associated beach flooding drive rapid erosion and groundwater salinization. After the storm, seawater flooding increases along the eroded coastline, limiting recovery of the high-elevation dunes and groundwater freshening. Collected data show that the state of coastal dunes controls the distribution of fresh groundwater on barrier islands, and rapid erosion can have prolonged but often overlooked impacts on available freshwater. These findings have important implications for understanding and managing coastal flood risks and water security on barrier islands in a changing climate. [ABSTRACT FROM AUTHOR]

Recent waste rock pile designs have been proposed to incorporate a fine-grained layer to create a capillary barrier to prevent surface water from draining into the pile interior. This study analyses active fibre optic distributed temperature sensing (FO-DTS) as a tool to measure the effectiveness a capillary barrier system following an infiltration test. A laboratory waste rock column was built with anorthosite waste rock overlain by sand. Volumetric water content is calculated during heat cycles lasting 15 min powered at 15 W/m in the column. A new algorithm is employed to circumvent several requirements for soil specific calibration. The inferred moisture contents were verified by soil moisture probes located adjacent to the cable. The FO-DTS data indicate, at vertical resolutions up to 2 cm, that water is retained in the sand and does not drain into the anorthosite following the infiltration test. The coefficient of determination, [R.sup.2], between the inferred and measured volumetric water content in the fine cover sand layer is 0.90, while the screened anorthosite maintained an [R.sup.2] of 0.94 with constant moisture content throughout the test. This study will ultimately help guide future waste rock storage design initiatives incorporating fibre optic sensors, leading to improved environmental mine waste management. Key words: distributed temperature sensing (DTS), soil moisture, fibre optic, waste rock, capillary barrier. Des conceptions recentes de pieux de steriles ont ete proposees pour incorporer une couche a grain fin afin de creer une barriere capillaire afin d'empecher l'eau de surface de s'ecouler dans l'interieur du pieu. Cette etude analyse la detection de temperature distribuee active par fibres optiques (FO-DTS) en tant qu'outil permettant de mesurer l'efficacite d'un systeme de barriere capillaire apres un test d'infiltration. Une colonne de steriles de laboratoire a ete construite avec des steriles d'anorthosite recouverte de sable. La teneur en eau volumetrique est calculee pendant les cycles de chauffage d'une duree de 15 min a 15 W/m dans la colonne. Un nouvel algorithme est utilise pour contourner plusieurs exigences relatives a l'etalonnage specifique au sol. Les teneurs en humidite inferees ont ete verifiees par des sondes d'humidite du sol situees a proximite du cable. Les donnees FO-DTS indiquent, a des resolutions verticales allant jusqu'a 2 cm, que l'eau est retenue dans le sable et ne s'ecoule pas dans l'anorthosite apres le test d'infiltration. Le coefficient de determination, [R.sup.2], entre la teneur en eau volumetrique deduite et mesuree dans la couche de sable fin est de 0,90, tandis que l'anorthosite tamisee maintient un [R.sup.2] de 0,94 avec une teneur en humidite constante tout au long de l'essai. Cette etude contribuera en fin de compte a orienter les futures initiatives de conception de stockage de steriles integrant des capteurs a fibre optique, permettant ainsi une meilleure gestion des dechets miniers dans l'environnement. [Traduit par la Redaction] Mots-cles: detection de temperature distribuee (DTS), humidite du sol, fibre optique, sterile, barriere capillaire., Introduction Waste rock--extracted coarse-grained rock below the ore cutoff grade--is stored on the surface of mine sites and exposed to natural climatic conditions. The most common method to store this [...]

Salt marshes are globally important ecosystems and thus their resilience to climate change holds societal importance. To date, studies addressing salt marsh responses to climate change have focused on sea‐level rise and biogeochemical feedbacks with increasing inundation. Less is known about how salt marsh sediment temperatures, which impact physical, biological, and chemical ecosystem processes, will respond to climate change. In this study, we present multi‐depth sediment temperature and porewater level data from low‐, mid‐, and high‐marsh sites at a New England salt marsh for a 1‐year period and investigate how salt marsh sediment temperatures respond to atmospheric and oceanic forcing. We use spectral analyses to identify the frequencies at which sediment temperatures vary and link the temperature variations to specific forcing mechanisms. We find that all sites across the marsh responded to air temperature with roughly equal amplitude whereas the responses to radiative heating and ocean tides varied spatially. The high‐marsh site is more sensitive to radiative heating than the mid‐ and low‐marsh sites. The low‐marsh is affected by tidal processes and inundation whereas the high‐ and mid‐marsh sites are not. In addition, we find that the bulk thermal diffusivity of the saturated sediments decreases with distance from the tidal channel. These factors contribute to considerable temporal and spatial variability in sediment temperatures with elevation, distance from the tidal channel, and time of year (season) being most important. [ABSTRACT FROM AUTHOR]

Oceanic storms can strongly disturb the physical and biogeochemical conditions of transitional coastal waters. Impacts of extreme oceanic storms on coastal ecosystems have received limited attention worldwide, with no studies at higher latitudes (> 45°) where tropical cyclones have usually abated. This study investigates the combined impacts from marine and atmospheric forcing on a coastal lagoon in Prince Edward Island, Canada, during and after Extratropical Cyclone Fiona in September 2022. Physical (water levels and temperature) and biogeochemical (dissolved oxygen [DO], electrical conductivity, pH, nitrate–nitrogen concentrations, total suspended solids [TSS]) datasets from the lagoon and the watershed's tributaries, groundwater springs, and piezometers were used to assess ecosystem disturbance and recovery timelines following the storm. Fiona resulted in a 1.6 m storm surge into the lagoon that elevated water temperatures by up to 6°C, disturbed the density‐dependent stratification of salinity and temperature, and reduced the diel amplitude of DO, indicating a reduction in plant respiration due to ecosystem disturbance. The freshwater tributaries revealed sharp changes in flow (30‐fold increase), nitrate–nitrogen (NO3‐N) concentrations and loading (70‐fold increase), and TSS loading (40‐fold increase) to the lagoon during and immediately following the storm. The lagoon rapidly recovered (hours) from the hydraulic disturbance of the storm surge, but elevated nutrient levels persisted for months. The intensity and frequency of extratropical cyclones is projected to increase in the Northwest Atlantic, making field‐based studies of cyclone impacts on coastal waters critical for understanding future coastal ecosystem disturbance and recovery periods relative to the timing of future storms. [ABSTRACT FROM AUTHOR]

Thermal mapping of surface waters and the land surface via UAVs offers exciting opportunities in many scientific disciplines; however, unresolved issues persist related to accuracy and drift of uncooled microbolometric thermal infrared (TIR) sensors. Curiously, most commercially available UAV-based TIR sensors are black, which will theoretically facilitate heating of the uncooled TIR sensor via absorbed solar radiation. Accordingly, we tested the hypothesis that modifying the surface absorptivity of uncooled TIR sensors can reduce thermal drift by limiting absorptance and associated microbolometer heating. We used two identical uncooled TIR sensors (DJI Zenmuse XT2) but retrofitted one with polished aluminum foil to alter the surface absorptivity and compared the temperature measurements from each sensor to the accurate measurements from instream temperature loggers. In addition, because TIR sensors are passive and measure longwave infrared radiation emitted from the environment, we tested the hypotheses that overcast conditions would reduce solar irradiance, and therefore induce thermal drift, and that increases in air temperature would induce thermal drift. The former is in contrast with the conceptual model of others who have proposed that flying in overcast conditions would increase sensor accuracy. We found the foil-shielded sensor yielded temperatures that were on average 2.2 °C more accurate than those of the matte black sensor (p < 0.0001). Further, we found positive correlations between light intensity (a proxy for incoming irradiance) and increased sensor accuracy for both sensors. Interestingly, light intensity explained 73% of the accuracy variability for the black sensor, but only 40% of the variability in accuracy deviations for the foil-shielded sensor. Unsurprisingly, an increase in air temperature led to a decrease in accuracy for both sensors, where air temperature explained 14% of the variability in accuracy for the black sensor and 31% of the accuracy variability for the foil-shielded sensor. We propose that the discrepancy between the amount of variability explained by light intensity and air temperature is due to changes in the heat energy budget arising from changes in the surface absorptivity. Additionally, we suggest fine-scale changes in river-bed reflectance led to errors in UAV thermal measurements. We conclude with a suite of guidelines for increasing the accuracy of uncooled UAV-based thermal mapping. [ABSTRACT FROM AUTHOR]