Lucie Gosset, Elisabeth Worliczek, Didier Richard, Mélanie Bertrand, Manuel Garcin, Catherine Sabinot, A-Tena Pidjo, Erosion torrentielle neige et avalanches (UR ETGR (ETNA)), Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), UMR 228 Espace-Dev, Espace pour le développement, Université de Guyane (UG)-Université des Antilles (UA)-Institut de Recherche pour le Développement (IRD)-Université de Perpignan Via Domitia (UPVD)-Avignon Université (AU)-Université de La Réunion (UR)-Université de Montpellier (UM), University of Natural Resources and Life Sciences (BOKU), Centre de Recherche sur l'Environnement et l'Aménagement (CRGA), Centre National de la Recherche Scientifique (CNRS)-École Nationale des Travaux Publics de l'État (ENTPE)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université Jean Moulin - Lyon 3 (UJML), Université de Lyon-Université Lumière - Lyon 2 (UL2), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), CNRT (French National centre for Technological Research) 'Nickel and its environment', Noumea, New Caledonia (CSF) 3PS2013, Institut de Recherche pour le Développement (IRD)-Université de Perpignan Via Domitia (UPVD)-Avignon Université (AU)-Université de La Réunion (UR)-Université de Montpellier (UM)-Université de Guyane (UG)-Université des Antilles (UA), Universität für Bodenkultur Wien = University of Natural Resources and Life [Vienne, Autriche] (BOKU), Environnement, Ville, Société (EVS), École normale supérieure de Lyon (ENS de Lyon)-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université Lumière - Lyon 2 (UL2)-Université Jean Moulin - Lyon 3 (UJML), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-École Nationale des Travaux Publics de l'État (ENTPE)-École nationale supérieure d'architecture de Lyon (ENSAL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure de Lyon (ENS de Lyon)-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-École Nationale des Travaux Publics de l'État (ENTPE)-École nationale supérieure d'architecture de Lyon (ENSAL)-Centre National de la Recherche Scientifique (CNRS)
International audience; Nickel mining in New Caledonia has largely contributed to the supply of sediment to watercourses, so that some of the main watercourses of the island are considerably aggraded. One of the consequences of this massive aggradation is the elevation and widening of river beds and creeks, thus increasing the flood hazard and the associated risks for people and goods. In addition, it changes the aquatic ecosystems, deteriorates the quality of drinking water supplies, causes the deposit of mud on crops during floods, damages communication networks and affects customary practices and activities.In this context, remediation measures are needed on a local level and they are required to consider technical aspects as well as social and cultural ones. Because of these requirements, the CNRT "Nickel and Environment" funds an applied and interdisciplinary research project with both physical and social sciences in order to (a) better understand local dynamics, and to (b) identify key factors for implementing remediation measures.In addition to physical observation and the modelling of aggradation, observations and experiences concerning river and creek aggradation were collected from the inhabitants of six tribes (Kanak villages) in the Thio Valley. It was equally important to record their perception regarding possible remediation measures, some of which having already been put in practice. In these testimonies, people often referred to 'water holes' in the rivers. These are socially important for inhabitants, and their sedimentary dynamics are well known to local people and could represent interesting markers of morphodynamic evolution.Linking lessons learned from both the physical and the social sciences approaches has led to the elaboration of a methodological guide dedicated to the management of sedimentary heritage from mining. This guide was presented to various actors in New Caledonia in 2018. Through the example of water holes as 'shared objects', this paper describes why and how the involvement of the inhabitants in the design and implementation of observations and monitoring is necessary and discusses the need to fully integrate people's perceptions into the project design.