Author(s): Achilleas Samaras; Theophanis Karambas

Linked Author(s): Achilleas Samaras

Keywords: Numerical model; Boussinesq equations; Coastal morphology; Erosion; Accretion

Abstract: Erosion poses a continuous threat for coasts and coastal communities worldwide. Nowadays coastal erosion is being intensively investigated due to the expected impact of climate change on the intensity of the drivers behind it (both natural- and human- induced) and its direct association to the inundation of low-lying areas. In the above context, numerical models are indispensable tools for the design of coastal protection and adaptation measures and, as such, their accuracy and reliability is continuously tested in both research and engineering applications. This work presents a new model for surf and swash zone morphology evolution induced by nonlinear waves. The nonlinear wave transformation in the surf and swash zone is computed by a nonlinear breaking wave model based on the higher order Boussinesq equations for breaking and non-breaking waves [1,2]. Regarding sediment transport, this work builds on the improvements introduced by [2] and adopts the latest update of the transport formula of [3] proposed by [4]. The wave and morphology evolution model is tested against two sets of experiments on beach profile change, namely the U.S. Army Corps of Engineers (CE) experiments and the Central Research Institute of Electric Power Industry (CRIEPI) experiments, as presented in [5]. The innovation of this work is the validation of a new Boussinesq-type morphology model under both erosive and accretive conditions in the foreshore (accretion is rarely examined in similar studies), which the model reproduces very well without modification of the empirical coefficients of the sediment transport formula proposed by [4] and without the use of an erosion/accretion criterion. The presented set of applications highlights model capabilities, as well as its suitability for coastal erosion mitigation and beach restoration design. References: [1] Karambas, T.V. and Koutitas, C. (2002). Surf and swash zone morphology evolution induced by nonlinear waves. Journal of Waterway, Port, Coastal and Ocean Engineering, 128 (3), pp.102-113. [2] Karambas, T.V. and Samaras, A.G. (2014). Soft shore protection methods: The use of advanced numerical models in the evaluation of beach nourishment. Ocean Engineering, 92, pp.129-136. [3] Camenen, B. and Larson, M. (2007). A unified sediment transport formulation for coastal inlet application. Technical Report, ERDC/CH: CR-07-1, US Army Corps of Engineers, Engineering Research and Development Center: Vicksburg, MS, USA, p.247. [4] Zhang, J. and Larson, M. (2020). A Numerical Model for Offshore Mound Evolution. Journal of Marine Science and Engineering, 8 (3), 160. [5] Dette, H.H. et al. (2002). Application of prototype flume tests for beach nourishment assessment. Coastal Engineering, 47 (2), pp.137-177.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022705

Year: 2022