Due to climate change, sea level rise, increasing frequency and intensity of storms, and growing population in low-lying coastal regions, the risk of flooding is expected to increase. Owing to these developments, maintenance and adaption of the existing coastal flood defence is often required. To meet this dilemma, the concept of multifunctional flood defence (MFFDs) is promoted. It aims at integrating urban functions with flood defence structures. Considering the threat from possible wave overtopping to the buildings on the top of coastal dikes in the low-lying highly populated regions like Belgium, this thesis focuses on advancing the understanding of the hydraulic impact of wave overtopping and developing a practical approach to assess the vulnerability of coastal buildings on the dike. The results can be used for the design and assessment of coastalMFFDs.Two-dimensional physical model tests were used to study wave overtopping and overtopping wave impact for the situation of coastal dikes where a shallow foreshore affects the wave overtopping.