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From 2014 to 2021 during the cyclone seasons, extensive monitoring of the hydrodynamics within a variety of lagoons of New Caledonia was conducted as a part of the PRESENCE project (PRESsures on coral Ecosystems of New CalEdonia). The PRESENCE project is aimed at building an efficient representation of the land–lagoon–ocean continuum at Grande Terre, New Caledonia's main island. Overall, coastal physical observations encompassed five different lagoons (four of which were never before monitored) and at least eight major atmospheric events ranging from tropical depressions to category 4 cyclones. The main objectives of this study were to characterize the processes controlling the hydrodynamics and hydrology of these lagoons (e.g., ocean–lagoon exchanges, circulation, level dynamics, temperature, and salinity variability), and to capture the magnitude of change during extreme events. An additional objective was to compile an adequate data set for future use in high-resolution hydrodynamic models. Autonomous oceanographic instruments were moored at strategic locations to collect time series of temperature, salinity, pressure, and Eulerian currents. Additionally, Lagrangian surface currents were observed through deploying drifter buoys, and cross-shore hydrological profile radials were carried out using CTDs (conductivity, temperature, depth). In total, five survey campaigns were conducted, beginning with the SPHYNX campaign which lasted 15 months (December 2014 to February 2016) in the Hienghène–Touho lagoon and ended with the 9 months NEMO campaign (September 2020 to April 2021) in Moindou lagoon. Between these were the 5 months NOUMEA campaign (December 2016 to April 2017) in Noumea lagoon, the 6 months ELADE campaign (February to August 2018) in the Poe lagoon, and the 5 months CADHYAK campaign (December 2019 to May 2020) in Koumac lagoon. In addition to characterizing these lagoons, the data set identifies important features and processes, such as the presence of internal waves on forereefs, wave-driven fluxes over reef barriers, and exchanges through passes. Signatures from strong events were also identified, including surges, thermal drops inside lagoons, and massive flash flood plume dispersion. Raw data sets were processed, controlled for quality, validated, and analyzed. Processed files are made publicly available in dedicated repositories on the SEANOE marine data platform in NetCDF format. Links (DOI) of individual data sets are provided herein.

From 2014 to 2021, extensive monitoring of hydrodynamics was deployed within a variety of lagoons of New Caledonia during 6 tropical cyclone seasons. Globally, those coastal physical observations encompassed five different lagoons (four of which were never monitored before) and at least eight major atmospheric events ranging from tropical depression to category 4 cyclone. The main objectives were to characterize the processes at stake controlling hydrodynamics and hydrology of these lagoons (e.g ocean-lagoon exchanges, circulation, level dynamics, temperature and salinity variability) and capture their magnitude of change during extreme events. An additional objective was to build an adequate data set for assessment of high-resolution hydrodynamics models. Those field experiments took place within the PRESENCE project (PRESsures on coral Ecosystems of New CalEdonia) which aimed at building an efficient representation of the land-lagoon-ocean continuum of Grande Terre (main land) lagoons. Autonomous oceanographic instruments were moored at strategic locations to collect time-series of temperature, salinity, pressure, eulerian currents which characterize hydrodynamics at best. During field trips, whenever possible, lagrangian drifters releases and cross-shore hydrological profiles radials were additionally carried out. Surveys begun chronologically with SPHYNX campaign which lasted 15 months (December 2014 to February 2016) in the Hienghène-Touho lagoon followed with 5 months records in NOUMEA lagoon (December 2016 to April 2017). ELADE campaign in Poe lagoon encompassed 2 periods of measure (February to April 2018 and June to August 2018). In Koumac lagoon, CADHYAK survey was carried out between December 2019 until the end of May 2020 and finally, data have been recorded continuously for 9 months in Moindou lagoon (NEMO) (September 2020 to April 2021). In addition to characterize these lagoons, this data set stresses out some important features and processes, such as the presence of internal waves on reef slopes, wave-driven fluxes over reef barrier and exchanges through passes. It also contains the signatures of strong events materialized by surges, thermal drops inside lagoons or massive flash flood plumes dispersion. Raw data sets were processed, quality-controlled and validated, and processed files are publicly available in dedicated repositories on Seanoe in NetCDF format. Links (DOI) of individual data sets are provided herein.

Ce rapport fait partie du projet de recherche PRESENCE (PRESions sur les Ecosystèmes récifo-lagonaires de Nouvelle-CalédoniE). L’objectif général de ce projet est de mieux appréhender le fonctionnement des lagons de Nouvelle-Calédonie à partir d’observations in-situ, de télédétection et de modélisation. Une des tâches de PRESENCE consiste notamment à étudier via des modèles hydrodynamiques le devenir des apports terrigènes au sein des lagons, et cela à l’échelle de la Grande Terre. Ce rapport présente la méthodologie utilisée et les données produites pour compléter le travail effectué lors de la création de l’Atlas 2011-2017 des apports hydriques à l’échelle du territoire calédonien (Lalau et al., 2019). En effet, ce premier rapport ne présentant qu’un nombre restreint de rivières - instrumentées par la DAVAR - nous ne disposions des données de débits aux exutoires que pour une faible portion du territoire. Afin de disposer d’une vision synoptique des apports hydriques sur l’ensemble de la Grande Terre pour les besoins de modélisation du continuum terre-lagons, il nous a fallu compléter ces données par des estimations des débits aux exutoires des principaux bassins versants non jaugés.

Ce rapport fait partie du projet PRESENCE (PRessions sur les Écosystèmes récifaux et lagonaires de Nouvelle-CalédoniE). L’objectif principal de ce projet est de mieux appréhender le fonctionnement des lagons de Nouvelle-Calédonie à partir d’observations in-situ, de télédétection et de modélisation hydrodynamique. L’étude développée dans ce rapport se concentre sur l’évaluation de la pertinence de recompositions harmoniques issues de l’atlas de marée FES2012 dans les lagons calédoniens afin de disposer d’un outil rapide pour quantifier la marée dans le cadre de travaux le nécessitant (e.g bathymétrie dérivée satellitaire, lâchers de bouées dérivantes lagrangiennes). Les résultats obtenus montrent une erreur commise plus importante par la prédiction de la marée en milieu lagonaire comparativement au milieu océanique, et ceci d’autant plus dans le cas de lagons fermés. Les cycles de mortes-eaux avec des états de mer océaniques faibles semblent être les périodes les plus propices à une bonne estimation de la marée autour de la Grand Terre.