Sediment transfers in a catchment under mountainuous and Mediterranean climate (Roya, Maritime Alps, France): conceptual model in climate change context ; Transferts sédimentaires dans un bassin versant à régime montagnard sous influence méditerranéenne (Roya, Alpes-Maritimes, France): modélisation conceptuelle en contexte de changement climatique

International audience ; For specific topographic and lithologic settings, sediment transfers at catchment scale primarily depends on hydrology, but also, at larger timescale, on climate change and land use. Since 2016 we adopted a source-to-sink approach to study sediment connectivity at catchment scale, in a watershed under mountainuous and mediterranean influences (Roya catchment: 60 km long, 660 km2). We displayed a bedload monitoring through RFID tracking and seismic continuous monitoring, coupled to an assessment of the sediment (dis)continuity (Fryirs et al., 2007).Folllowing a European project dealing with climate change mitigation strategies in the Roya valley (Projet Interreg V-A Alcotra Italie-France n°1712 "Concert-Eaux"), an extreme event occurred in the catchment (Storm Alex on Oct. 2nd, 2020: rainfall return period > 1000 yrs on the upstream part of the catchment: CEREMA, 2021 ; peak flow return period between 100 and 500 yrs ; characterization of the morphogenic effect of the flood: between 600 and 1000 yrs return period: DDTM 06, ONF-RTM, Inrae, 2022). This triggers the occasion to consider the effects of climate change on sediment fluxes at catchment scale, comparing "ordinary regime" vs. "with occurrence of an extreme event". We developed a prospective conceptual model for sediment fluxes at catchment scale in climate change context. We suggest to integrate bedload monitoring results before and after remobilization of sediment stock in the floodplain as a consequence to Storm Alex, and climate projections at 100 yrs on the catchment. ; Pour un contexte topographique et lithologique donné, les transferts sédimentaires à l’échelle d’un bassin versant sont dépendants en premier lieu de l’hydrologie, mais aussi, à plus large échelle temporelle, de l’évolution du climat et de l’occupation du sol. Depuis 2016 nous avons adopté une approche source-to-sink pour appréhender la connectivité sédimentaire à l’échelle d’un bassin versant soumis à régime montagnard sous influence méditerranéenne (bassin ...