Ports exist at the intersection of human activities and the highly-vulnerable natural environment. However, the interactions with the adjacent coastal areas are usually disregarded. This work presents a modelling chain to assess the role of seaports on coastal flood and erosion hazards. It relies on a nearshore evolution model capable of efficiently reproducing the beachfront evolution at areas affected by coastal infrastructures in the long-term. Morphological changes are then used to update the digital terrain model used in flood simulations. The methodology is demonstrated at a 40 km coastal stretch in the Mediterranean Sea affected by successive enlargements of the port of Valencia (Spain). The impact assessment methodology developed in this work can serve as the basis to support flooding and sediment-related risk assessments and adaptation planning within port-coast systems.