The future of coastal wetlands and their ecological value depend on their capacity to adapt to the interacting effects of human impacts and sea-level rise. Even though extensive wetland loss due to submergence is a possible scenario, its magnitude is highly uncertain due to limited understandig of hydrodinamic and bio-geomorphic attenuation and consequent wetland evolution is poorly understood. Predicitons are further complicated by the presence of a number of vegetation types that change over time and also contribute to flow attenuation. Here, we show that flow attenuation affects wetland vegetation by modifying its wetting-drying regime and inundation depth, increasing its vulnerability to sea-level rise. Our simulatios for an Australian subtropical wetland predict much faster wetland loss than commonly used moldes that do not consider flow attenuation.School of Enginering and Centre for Water Security and Environmental Sustainability, The University of Newcastle, Callaghan 2308, AustraliaDepartment of Environmental Sciences, Macquarie University, North Ryde 2019, AustraliaDepartment of Hydraulics and Research Council of National University of Rosario (CIUNR), Rosario 2000, Argentina