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L'UMR EMMAH : Environnement Méditerranéen et Modélisation des Agro-Hydrosystèmes

Les recherches menées par l’UMR EMMAH portent sur la compréhension et la modélisation du fonctionnement des agrosystèmes en interaction avec les hydrosystèmes souterrains. Ceci amène l’UMR à considérer le système aquifère-sol-plante-atmosphère à différentes échelles de temps et d’espace. Le fonctionnement de ce système nécessite, pour le comprendre et le modéliser, de prendre en compte de nombreuses interactions entre la dynamique du couvert végétal, les processus physiques, chimiques, biologiques dans les sols, les interactions avec l’atmosphère et les hydrosystèmes ainsi que les modalités de gestion des agrosystèmes. Les travaux menés visent, notamment, à caractériser à différentes échelles spatiales (du millimètre au kilomètre) et temporelles (de la seconde à quelques décennies), les flux de masse entre l’atmosphère, le couvert végétal, le sol et l’aquifère souterrain et les processus intervenant dans la production végétale en relation avec les facteurs du milieu. Ainsi, l’UMR EMMAH contribue à l’évaluation de la durabilité des ressources hydriques souterraines et des systèmes de culture dans un double contexte de changements globaux et de transition agroécologique. Le pourtour méditerranéen reste un terrain d’étude privilégié, région marquée par une évolution rapide du climat et des tensions fortes sur l’eau liées à l’adaptation des systèmes de cultures et une forte pression démographique.

Photo de Quentin Didier
article

28 octobre 2024

Rédaction : Q. Didier, Emmah web

Soutenance de thèse

Quentin Didier soutiendra, le lundi 4 novembre à 14h à la salle des thèses d'Avignon Université, sa thèse de Doctorat intitulée : "Caractérisation de milieux naturels à l’échelle macroscopique par approches ondulatoires mécanique et électromagnétique. Application à l’étude de l’impact de la teneur en eau sur les caractéristiques physiques d’un milieu hétérogène".
aporrectodea caliginosa.JPG

Durant l'année scolaire 2024-2025, un projet de recherche participative, porté par Céline Pelosi (EMMAH) en partenariat avec la Région académique Provence-Alpes-Côte d'Azur, est proposé aux classes du CP au CM2 à l’échelle nationale (hexagone).

Mercredi 16 octobre le premier séminaire plénier qui lance le projet PETTA se réunissait au Pradel-Domaine Olivier de Serres (Ardèche).

Visite 1ere Pro La Ricarde 4.jpg

Ce jeudi 17 octobre, l'UMR Emmah a accueilli des élèves de 1ere pro du lycée agricole La Ricarde de L’Isle sur la Sorgue.

HAL : Dernières publications

  • [hal-04762660] Mapping global drought-induced forest mortality based on multiple satellite vegetation optical depth data

    The frequency and intensity of global drought events are continuously increasing, posing an elevated risk of forest mortality worldwide. Accurately understanding the impact of drought on forests, particularly the distribution of mortality due to drought, is crucial for scientifically understanding global ecological drought. Atmospheric indicators and soil moisture are typically correlated with tree growth and influence tree water status and drought severity; however, they do not directly represent forest drought conditions. Optical vegetation indices reflect forest mortality but are affected by response delays, low temporal resolution, and cloud contamination. Therefore, the accuracy of current assessment methods for global drought-induced forest mortality, which are based on meteorological and vegetation variables, still needs improvement. To address this challenge, we utilized vegetation optical depth (VOD) data to characterize the changes in forest canopy moisture due to drought. VOD is a parameter that describes the transmissivity of vegetation in the microwave band and is closely related to forest water content and biomass, with longer wavelengths and greater penetration capabilities than visible and near-infrared remote sensing signals. We calculated the annual variation of VOD (ΔVOD) as a supplementary indicator to enhance the accuracy of monitoring and modeling of global drought-induced forest mortality. We integrated VOD with vegetation indices, meteorological data, terrain, and other variables to construct a predictive model of forest mortality due to drought and used this model to generate a series of global maps depicting drought-induced forest mortality. The results indicated that variables related to VOD contributed significantly to the mortality model compared with those based on vegetation or meteorological variables. Furthermore, ΔVOD exhibited a higher correlation with reference mortality rates compared to relative water content, the enhanced vegetation index, and climate water deficit. Notably, by validating the model fit with reference mortality rates, we found that incorporating ΔVOD into the model improved the accuracy of the global forest mortality map from R2 = 0.45 to R2 = 0.63. By optimizing the training points using a two-stage correlation threshold between ΔVOD and the reference mortality, map accuracy was further improved to R2 = 0.72. This study highlights the effectiveness of VOD, particularly ΔVOD, as a direct indicator of vegetation water content variation, for predicting drought-induced forest mortality. The global forest mortality map obtained from 2014 to 2018 is of significant value for the further analysis of forest carbon variations induced by extreme global drought events.

    ano.nymous@ccsd.cnrs.fr.invalid (Xiang Zhang) 31 Oct 2024

    https://hal.inrae.fr/hal-04762660v1
  • [hal-04761776] The Multi-Parameter Mapping of Groundwater Quality in the Bourgogne-Franche-Comté Region (France) for Spatially Based Monitoring Management

    Groundwater, a vital resource for providing drinking water to populations, must be managed sustainably to ensure its availability and quality. This study aims to assess the groundwater quality in the Bourgogne-Franche-Comté region (~50,000 km2) of France and identify the processes responsible for its variability. Data were extracted from the Sise-Eaux database, resulting in an initial sparse matrix comprising 8723 samples and over 100 bacteriological and physicochemical parameters. From this, a refined full matrix of 3569 samples and 22 key parameters was selected. The data underwent logarithmic transformation before applying principal component analysis (PCA) to reduce the dimensionality of the dataset. The analysis of the spatial structure, using both raw and directional variograms, revealed a categorization of parameters, grouping major ions according to the regional lithology. Bacteriological criteria (Escherichia coli and Enterococcus) displayed strong spatial variability over short distances, whereas iron (Fe) and nitrates showed intermediate spatial characteristics between bacteriology and major ions. The PCA allowed the creation of synthetic maps, with the first seven capturing 80% of the information contained in the database, effectively replacing the individual parameter maps. These synthetic maps highlighted the different processes driving the spatial variations in each quality criterion. On a regional scale, the variations in fecal contamination were found to be multifactorial, with significant influences captured by the first four principal components. The 22 parameters can be grouped into six categories based on their spatial and temporal variations, allowing for the redefinition of a resource management and monitoring strategy that is adapted to the identified spatial patterns and processes at the regional scale, while also reducing analytical costs.

    ano.nymous@ccsd.cnrs.fr.invalid (Abderrahim Bousouis) 31 Oct 2024

    https://hal.inrae.fr/hal-04761776v1
  • [hal-04750548] A global analysis of nearshore and submarine springs: spatial distribution, controlling factors, and probability of presence

    Coastal springs act as bi-directionally preferential flow paths between coastal aquifers and oceans. While these springs can supply coastal ecosystems with nutrients, they also present vulnerabilities such as contamination and seawater intrusion. Despite their significance, substantial knowledge gaps exist regarding coastal springs due to their complex hydrogeological nature. This study provides a comprehensive global assessment of coastal springs, focusing on their distribution, controlling factors, and likelihood of occurrence. A global dataset of known coastal springs was compiled and analyzed, revealing 66 % of identified springs in the Mediterranean region, mainly linked to karst systems. In contrast, fewer springs were noted in Africa, South America, and South Asia. Key factors influencing spring occurrence were examined using geostatistical methods and integrated into a multi-criteria decision-making framework to develop a Coastal Spring Probability Index (CSPI) along coastline. High-potential areas for coastal springs were identified in regions characterized by significant carbonate and volcanic rock formations, wetter climates, and active tectonic margins, such as southern Europe, the Caribbean, tropical islands, and eastern Asia. Conversely, regions with dry climates and high water demand, such as North Africa and South America, exhibited a lower likelihood of spring presence. These findings will serve as a baseline for local-scale studies and aimed at improving coastal spring inventories and establishing monitoring networks. It will contribute to vulnerability assessment studies, thereby enhancing the management of coastal groundwater resources. The study emphasizes the importance of multidisciplinary approaches to understand coastal spring dynamics and advocates for a strategic planning in groundwater management and conservation. Ongoing efforts to inventory and monitor coastal springs, coupled with targeted conservation measures, are essential for ensuring the long-term sustainability of coastal water resources and ecosystems.

    ano.nymous@ccsd.cnrs.fr.invalid (Houssne Bouimouass) 23 Oct 2024

    https://hal.inrae.fr/hal-04750548v1