For reasons of computational efficiency, 1D XBeach cross-shore transect models are often applied on quasi alongshore-uniform coasts instead of a more computationally expensive 2DH modelling approach. In this paper we describe a practical methodology to allow 1D models to mimic infragravity wave growth observed in field conditions and represented in 2DH models and thereby significantly reduce the overestimation of infragravity wave heights near to the shore. We show that even if the coastal setting may support the 1D model assumption of alongshore uniformity in forcing and bathymetry, 1D XBeach models will overestimate infragravity wave growth relative to field conditions due to the underlying assumption of alongshore-uniform intra-wave (group) hydrodynamics common to all wave (group)-resolving models. Model analysis showed little variation in the optimum calibration value of this approach for a large range of wave forcing conditions (wave height, period and directional spread) and consistency with 2DH model results for a large range of Dutch coastal profiles. Comparison to field observations showed that the methodology significantly increased the skill of the 1D model to simulate nearshore IG wave heights. These results have implications on the ability to accurately predict the response of these coasts to energetic events, which is crucial to assess current and future flood risk and to design effective flood protection and mitigation measures.@en

Wave overtopping is commonly measured using overtopping tanks. In this paper, an alternative system is developed by using two laser scanners. It measures wave run-up, as well as layer thicknesses and front velocities, both during normally and obliquely incident waves on a dike in the field. The paper considers the first field validation tests with the system, with normal and oblique waves generated by the wave run-up simulator on a grass dike slope. Furthermore, a range of environmental conditions are simulated, to determine the robustness of the system. From the measured distance and reflection, the run-up is determined, which corresponds well to the observed run-up. From the data, the layer thickness and front velocity are determined as well. Layer thicknesses and front velocities are determined reliably with the laser scanners. Also, the (virtual) wave overtopping discharge can be calculated, which corresponds well with the most commonly used overtopping equations.@en