Composite Beaches and Dynamic Revetments - Coastal Protection Inspired by Nature

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Climate change represents a significant issue for coastal protection, rising sea levels and more intense storms will lead to increased erosion of the coastline. At present it is predicted that 24% of coastlines are losing 0.5 m/yr (Luijendijk, et al., 2018). It is therefore vital that new protection approaches are designed, dynamic revetments could be part of that solution.These are based on naturally occurring formations displayed by composite beaches. It comprises of a backshore ridge constructed from gravel or cobbles and a foreshore of sand. The backshore ridge is reshaped continuously under influences such as wave attack, however, the overall structure shows a good level of stability regardless. It is expected to result in erosion control for both the upper beach and hinterland as well as effective overtopping protection. This hypothesis is supported by both the DYNAREV experiment (Blenkinsopp, et al., 2019) and the few existing structures, such as that in North Cove, Washington. At present there is a general lack of research into dynamic revetments, an area which needs development is the modelling of these revetments. Currently, the main tool is X-Beach software and its many variants. There are however issues with the existing models many of which relate to the inability to simulate sediment transport within the cobblestone layer accurately. This project primarily proposes to develop the x-beach model to more accurately simulate dynamic revetments and use this to answer questions related to the long-term viability and practicality of these structures.Further, this will be supported with a second experiment which will be assisted with as part of the PhD. Currently, named DYNAREV 1.5 the proposed experiment will largely mimic the first experiment by physically modelling a dynamic revetment in a large wave flume. The main difference being the range of cobble sizes used. There will be a wealth of data which will need to be analysed as a result and later used as a data set for model calibration and validation.Finally, through drawing on both the natural and artificial revetments it may be possible to understand how the structures will respond to climate change and rising seas. The produced model will be able to either support or detract from the current belief that these structures are largely resistant to such influences.