Figure 1 Overtopping wave threats the waterfront buildings, England coast, 2014 Winter
In a populated coastal town in Europe, urban development along the waterfront is attractive, although the space is restricted. The residential and commercial developments along UK and Mediterranean shorelines are just behind the sea defence (Allsop et al., 2005); Whereas, similar development in Belgium and the Netherlands typically are on the top of a sea dike. The development and people within this densely waterfront area would experience significant hazards from wave overtopping when the coastal defence structure is lower than the water level (Chen et al, 2015), see Figure 1. However, users and owners of the waterfront properties may be unaware of the potential effects of wave overtopping in storm conditions (Allsop et al., 2005). With climate change and sea level rise, an increasing storm intensity and more serious overtopping events are expected. The overtopping wave actions on the waterfront buildings (e.g., Figure 2) would become more common.
The aims of this study are to investigate the impact mechanisms of the overtopping wave on the buildings standing on the dike, and to develop an empirical formula to predict the overtopping wave load on a vertical wall on the wide crested dike, such as found in low-lying countries (e.g., Belgium and the Netherlands). The outcome of this study can be used to help answering the following questions:
1) Whether the existing building is safe under design conditions?
2) Which extreme conditions would lead to failure?
3) How to let the current buildings be strong enough to against extreme wave load (or transfer their solely living function to partly flood defence) in the future?
4) How to improve the usage of the shoreline space and explore the next generation of the urbanized coastal flood defence?
Figure 2 The whole process of overtopping flow impacting on the building: ①Wind generates waves far away from shoreline; ②Offshore waves coming into the foreshore area, increasing wave height, decreasing wave length. Finally, most waves breaking and wave energy dissipating in the form of turbulence bore. ③Turbulent bore (broken wave) running up on the seaward slope of a dike and overtopping the crest of the dike; ④ Part of the overtopping flow continue propagating along the dike crest and the other part flowing back seaward; ⑤ Overtopping flow hitting the building, with some of it being reflected seaward, some passing through buildings; and ⑥Overtopping flow going landward.
References
Allosp, W,2005, CLASH Work Package 6, Analysis of overtopping hazards
Chen, X., Hoand, B., Altomare, C., Suzuki, T., Uijttewaal, W., 2015. Forces on a vertical wall on a dike crest due to overtopping ow. Coastal Engineering 95, 94-104
Chen, X., Hoand, B., Altomare, C., Suzuki, T., Uijttewaal, W., 2015. Forces on a vertical wall on a dike crest due to overtopping ow. Coastal Engineering 95, 94-104
