Coastal zones are essential for social and economical developments. Located at the interface between ocean and continent, the coasts are vulnerable to environmental hazard and are currently facing an intensification of risk associated with increasing human pressure and the context of global climate change. This project focuses on two regions of the world particularly exposed to coastal vulnerability: West Africa and Vietnam. The environmental conditions governing hydro-sedimentary functioning differ drastically between the two regions. Erosion in West Africa is induced all year long by high-energy long swells; in contrast, Vietnam shows paroxystic events induced by typhoons. Even though the societal issues are manifest in these areas, their hydro-sedimentary functioning remains poorly known and limits social and economical development. The objective of the COASTVAR project is to advance our understanding by characterizing the morphological evolution (aerial and submerged), the driving forces and hydro-morphodynamic processes, from event to seasonal and interannual scales. Emphasis will be given to extreme events and their long-term effect, and to surf-shelf exchanges associated with the wave-induced circulation. In the first project task, innovative observational tools (video imagery and drone) will be used in addition to conventional instruments. In a second task, deep-water wave conditions will be downscaled to the beach, then nearshore configurations of a 3D coupled wave-current model will be set up. In a third task, the ECORS beach evolution predictor (PEA SHOM-DGA), which was yet only tested in mid-latitude environments, will be applied for the first time to tropical coastal systems. Our objective here is to obtain a generic operational tool that can be applied to any coast in the world. The research developed in the COASTVAR project has a strong dual aspect. First, it will provide the first high quality survey and forecasting system for the selected regions (waves, currents and bathymetry), which will be highly relevant to military action. Then, it will propose tools to anticipate coastal risks (erosion and submersion), quantify vulnerability and exposure of people to hazard, and lay solid grounds to improve coastal management.