Relationships between the tide and fatal drowning at surf beaches in New South Wales, Australia: Implications for coastal safety management and practice
Beaches are popular, recreational destinations, but can be hazardous environments where drowning fatalities and other types of injuries can occur. Ocean lifeguards and beach safety managers make operational safety decisions based on ocean conditions, including various elements of the tide. This study addresses assumptions about the tide that are common in beach safety management; assessing the scientific basis that informs these decisions by evaluating the relationship between elements of the tide and fatal drowning on microtidal surf beaches in New South Wales (NSW), Australia. Lower tidal water levels and time periods closer to low tide were associated with increased likelihood of fatal drowning at surf beaches, while tidal phase (rising vs falling), tide range, and the rate of change of falling or rising water levels were not. These results have implications for ocean safety management and those responsible for educating the public about beach safety issues. Broad statements or anecdotal opinions that are not location or beach-specific should avoid describing times with falling water levels (an outgoing tide) as being inherently more dangerous.
(Ocean and Coastal Management. vol. 238, n° 0964-5691, pp. 106584, 01/05/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Data quality control considerations in multivariate environmental monitoring: experience of the French coastal network SOMLIT
Introduction While crucial to ensuring the production of accurate and high-quality data—and to avoid erroneous conclusions—data quality control (QC) in environmental monitoring datasets is still poorly documented. Methods With a focus on annual inter-laboratory comparison (ILC) exercises performed in the context of the French coastal monitoring SOMLIT network, we share here a pragmatic approach to QC, which allows the calculation of systematic and random errors, measurement uncertainty, and individual performance. After an overview of the different QC actions applied to fulfill requirements for quality and competence, we report equipment, accommodation, design of the ILC exercises, and statistical methodology specially adapted to small environmental networks (<20 laboratories) and multivariate datasets. Finally, the expanded uncertainty of measurement for 20 environmental variables routinely measured by SOMLIT from discrete sampling—including Essential Ocean Variables—is provided. Results, Discussion, Conclusion The examination of the temporal variations (2001–2021) in the repeatability, reproducibility, and trueness of the SOMLIT network over time confirms the essential role of ILC exercises as a tool for the continuous improvement of data quality in environmental monitoring datasets.
(Frontiers in Marine Science. vol. 10, n° 2296-7745, pp. 12, 26/04/2023)
LOG, INSU - CNRS, ULCO, CNRS, IRD [Ile-de-France], ULCO, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS, BOREA, UNICAEN, NU, MNHN, IRD, SU, CNRS, UA, AD2M, CNRS, SBR, SU, CNRS, LIENSs, INSU - CNRS, ULR, CNRS, LOV, INSU - CNRS, SU, CNRS, IMEV, INSU - CNRS, SU, CNRS, INSU - CNRS, CNRS, UA, UM, OSU OREME, INSU - CNRS, CNRS, INRAE, UM, SBR, SU, CNRS, ISTerre, IRD, INSU - CNRS, USMB [Université de Savoie] [Université de Chambéry], CNRS, Fédération OSUG, UGA, PACEA, UB, CNRS, CAPENA, CREC, UNICAEN, NU, LOMIC, INSU - CNRS, SU, CNRS, OOB, SU, CNRS, CPPM, AMU, IN2P3, CNRS, IMEV, INSU - CNRS, SU, CNRS, GIPREB, CRESCO, MNHN, IFREMER, UNICAEN, NU, MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, IRD, UBO EPE, CNRS, IPREM, UPPA, INC-CNRS, CNRS, OOB, SU, CNRS, AD2M, SBR, UPMC, CNRS, UPMC, CNRS, UMR MARBEC, IRD, IFREMER, CNRS, UM, TUMSAT, STAMAR, INSU - CNRS, SU, CNRS
Assessment of organochlorine contamination source and ecological risk in the Litani River: polychlorinated biphenyls and organochlorinated pesticides in surface sediments
In this paper, we investigate for the first time the contamination source and the ecological risk associated to organochlorinated compounds in the Litani system. For this purpose, the levels of 7 polychlorinated biphenyls (PCBs) and 13 organochlorinated pesticides (OCPs) were assessed, using a microwave-assisted extraction coupled to gas chromatography-electron capture detector (MAE/GC-ECD) method, in surficial sediments from 30 sites along the main course of the river, two major tributaries, and the Quaraoun Lake. ∑7PCBs exhibited total concentrations ranging from 0.11 to 8 ng g−1 of dry weight and are not able apparently to pose ecological risks since none of the samples showed concentration above the effects range low (ERL) guideline (22.7 ng g−1). The detected levels of OCPs in the river were significantly higher than those of PCBs; ∑13OCPs range from 0.5 to 46.5 ng g−1 of dry weight. Overall, the integrated eco-toxicological risk imposed by the organochlorine contamination in the Litani River, estimated as the mean effects range medium quotient (mERMq), is considered low with risk probability lower than 21% in all sites. The six dichlorodiphenyltrichloroethane-based pesticides (∑6DDT) contributed to more than 70% of the mERMq in 15 over the 29 included sites. Moreover, the approach of ∑6DDT/∑7PCB ratios was applied to investigate the contamination source. ∑6DDT/∑7PCB was higher than one in all samples suggesting that the organochlorine contamination result from agricultural activities set in the surrounding areas of the Litani River.
(Environmental Science and Pollution Research. vol. 30, n° 0944-1344, pp. 66125-66134, 25/04/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Reconstruction des changements environnementaux et climatiques entre ca 50 - 35 ka et potentiel impact sur les changements culturels des Néandertaliens et des Hommes anatomiquement modernes dans le sud de la France
Déterminer l'impact des variations climatiques sur les changements culturels passés est une tâche difficile en raison des incertitudes chronologiques inhérentes aux méthodes de datation appliquées aux archives archéologiques et paléoclimatiques, mais également de la différence de résolution temporelle de ces deux archives. Nous présentons deux séquences paléoenvironnementales à partir d’une étude pollinique à haute résolution, provenant du golfe de Gascogne (45°21'N, 5°13'W) et du golfe du Lion (40°29'N, 4°01'E). Ces séquences sont bien contraintes par des datations numériques (nouveaux âges IRSL pour la carotte marine du golfe de Gascogne) et de nouveaux modèles âge-profondeur bayésiens, incluant des contraintes stratigraphiques entre les profondeurs datées. Ces séquences permettent l’identification des changements climatiques et de végétation à l'échelle millénaire dans le sud de la France associés aux événements de réchauffement et de refroidissement du Groenland (cycles de Dansgaard-Oeschger, D-O) et aux décharges massives d'icebergs dans l'Atlantique Nord (événements de Heinrich, HE). Les deux nouvelles chronologies des paléoenvironnements et climats ont été confrontées à une chronologie actualisée des changements culturels des Néandertaliens et des Hommes anatomiquement modernes (HAM) dans le sud de la France, lors de la période de transition du Paléolithique moyen au Paléolithique supérieur (ca 50 – 35 ka). Les deux enregistrements paléoenvironnementaux du sud-ouest et du sud-est de la France montrent différentes amplitudes régionales des expansions de la forêt tempérée aux réchauffements de D-O et du semi-désert pendant les HE. Malgré l'amélioration des chronologies paléoclimatiques et archéologiques, l'identification d'un impact potentiel du climat et des environnements sur les changements culturels reste encore difficile en raison de nouvelles incertitudes notamment liées au nouveau modèle d’âge. Néanmoins, cette étude suggère que l'ouverture progressive du paysage depuis le D-O 12 (ca 47 ka) aurait favorisé l'arrivée des HAM en Europe occidentale, entraînant une compétition avec les Néandertaliens pour les mêmes niches écologiques, et donc la disparition de ces derniers dans la région vers 40 ka.
(18/04/2023)
UB, UBM, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EPHE, PSL, LCE, CNRS, UFC, UBFC, UQAT, LMJL, CNRS, Nantes univ - UFR ST, Nantes Univ
PHANGS-MUSE: Detection and Bayesian classification of ~40 000 ionised nebulae in nearby spiral galaxies
In this work, we present a new catalogue of >40 000 ionised nebulae distributed across the 19 galaxies observed by the PHANGS-MUSE survey. The nebulae have been classified using a new model-comparison-based algorithm that exploits the odds ratio principle to assign a probabilistic classification to each nebula in the sample. The resulting catalogue is the largest catalogue containing complete spectral and spatial information for a variety of ionised nebulae available so far in the literature. We developed this new algorithm to address some of the main limitations of the traditional classification criteria, such as their binarity, the sharpness of the involved limits, and the limited amount of data they rely on for the classification. The analysis of the catalogue shows that the algorithm performs well when selecting H II regions. In fact, we can recover their luminosity function, and its properties are in line with what is available in the literature. We also identify a rather significant population of shock-ionised regions (mostly composed of supernova remnants), which is an order of magnitude larger than any other homogeneous catalogue of supernova remnants currently available in the literature. The number of supernova remnants we identify per galaxy is in line with results in our Galaxy and in other very nearby sources. However, limitations in the source detection algorithm result in an incomplete sample of planetary nebulae, even though their classification seems robust. Finally, we demonstrate how applying a correction for the contribution of the diffuse ionised gas to the nebulae’s spectra is essential to obtain a robust classification of the objects and how a correct measurement of the extinction using diffuse-ionised-gas-corrected line fluxes prompts the use of a higher theoretical H α /H β ratio (3.03) than what is commonly used when recovering the E ( B – V ) via the Balmer decrement technique in massive star-forming galaxies.
(Astronomy & Astrophysics - A&A. vol. 672, n° 0004-6361, pp. A148, 17/04/2023)
LERMA, LERMA, ENS-PSL, PSL, INSU - CNRS, CNRS, PSL, SU, CNRS, CY, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, MPIA, ESO, CRAL, ENS de Lyon, UCBL, INSU - CNRS, CNRS, ANU, AlfA, UW, IAO, SB RAS, OSU, UAB
FOREDUNE GUIDED REMOBILIZATION EXPERIMENTS ALONG THE SOUTHWEST COAST OF FRANCE
This contribution presents the response of experimental management methods implemented along 2 km stretch of the southwest coast of France with the objective to restore aeolian dynamics and foredune mobility to promote quasi alongshore-uniform landward foredune migration. The analysis based on eight airborne LiDAR campaigns and several morphometric indicators shows that the alongshore and temporal variability of foredune evolution depends on natural dynamics and contrasted managed strategies. These experiments offer new perspectives and guidelines for coastal dune managers in areas where chronic erosion threatens fixed dune systems.
(pp. 642-646, 15/04/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
ON THE IMPACT OF HEADLAND BYPASSING ON SHORELINE CHANGE IN A ONE-LINE MODEL
The knowledge of future long-term sandy shoreline evolution is necessary for sustainable coastline management. However, the impact of sediment transport due to headland sand bypassing is not yet well addressed in shoreline models. This work aims at implementing a parametric expression for sand bypassing in the reduced complexity shoreline model LX-Shore. The parametrization of the wave-forced sediment bypassing around an isolated headland developed by McCarroll et al. (2021) is implemented. Considering an idealized configuration of a 300-m long, initially straight, sandy coast with a rectangular headland, results show that headland sand bypassing has a substantial impact on the downdrift (updrift) erosion (accretion) pattern and magnitude. Our simulations imply that taking into account bypass transport in long-term shoreline models such as LX-Shore could provide new insights into coastal embayment changes.
(pp. 1364-1371, 15/04/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
SATELLITE-BASED SHORELINE DETECTION FOR MACRO-TIDAL COASTS: IMPACTS OF MORPHOLOGICAL AND HYDRODYNAMIC SETTING
Robust and accurate long-term mapping of the shoreline is a fundamental requirement for effective coastal management and policy making. Earth observation (EO) coupled with novel image analysis techniques have demonstrated the potential of EO for long-term, local, regional, and even global scale investigations of shoreline change. However, satellitederived shoreline (SDS) data is associated with large uncertainties relating to environmental factors, tidal range, and wave action among other factors. This contribution investigates the impacts of morphological and hydrodynamic setting on the accuracy of SDS in macrotidal, high-energy coasts. Results revealed significant differences in SDS accuracy between the two morphologically contrasting sites in terms of the level of error and the optimal water level correction. We show that SDS accuracy at macrotidal sites can be greatly improved by applying appropriate water level corrections and that a different approach is required depending on beach type (dissipative/reflective).
(pp. 1392-1402, 15/04/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
UNDERSTANDING COASTAL CHANGE FROM NOISY SATELLITE-DERIVED SHORELINE DATASETS: INFLUENCE OF TIDE AND RUNUP CORRECTION AND SPATIAL AVERAGING
Free-of-charge publicly available optical satellite imagery can now be used to provide short-term to multi-decadal shoreline satellite-derived shoreline (SDS) data, with errors typically under 10 m on microtidal beaches. However, SDS accuracy dramatically worsens at high-energy and/or meso to macrotidal lowgradient beaches, which challenges a robust assessment of shoreline variability and trends. In this contribution we demonstrate that, on such beaches, water level (tide + runup) correction and/or an adapted space-averaging of uncorrected (noisy) SDS dataset can substantially reduce uncertainties and thus allow addressing the timeand space variability of shoreline change and their primary drivers.
(pp. 1347-1353, 15/04/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
MULTIDECADAL SHORELINE VARIABILITY LINKED WITH ESTUARINE SANDBANK WELDING: THE NORTH MEDOC COAST, SOUTHWEST FRANCE
(pp. 1452-1457, 11/04/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS