Abstract
With large-scale human interventions and climate change unfolding as they are now, coastal changes at decadal timescales are not limited to incremental modifications of systems that are fixed in their general geometry, but often show significant changes in layout that may be catastrophic for populations living in previously safe areas. This poses severe challenges that are difficult to meet for existing models. A new free-form coastline model, ShorelineS, is presented that is able to describe large coastal transformations based on relatively simple principles of (1) alongshore transport gradient driven changes as a result of coastline curvature and (2) spit formation at high-angle wave incidence. An arbitrary number of coast sections is supported, which can be open or closed and can interact with each other through relatively straightforward merging and splitting mechanisms. Rocky parts or structures may block wave energy and/or longshore sediment transport. These features allow for a rich behavior including shoreline undulations and formation of spits, migrating islands, merging of coastal shapes, salients and tombolos. The main formulations of the (open-source) model are presented. Test cases show the capabilities of the flexible, vector-based model approach, while field validation cases for a large-scale sand nourishment (the Sand Engine; 21 million m3) and an accreting groyne scheme at Al-Gamil (Egypt) show the model’s capability of computing realistic rates of coastline change as well as a good representation of the shoreline shape for real situations.
Highlights
Sandy beaches are extremely valuable natural resources, providing the first line of defense against coastal storm impacts, as well as other ecosystem services (Barbier et al, 2011) such as ecological habitats and recreation areas
Coastline changes along sandy beaches at timescales beyond events and seasons often are dominated by gradients in wavedriven longshore transport
The first practical concept for predicting coastline change due to interruption of this wavedriven longshore transport was developed by Pelnard-Considère (1956), who derived a diffusion-type equation based on the assumptions of a small angle of incidence and a constant crossshore profile shape
Summary
Sandy beaches are extremely valuable natural resources, providing the first line of defense against coastal storm impacts, as well as other ecosystem services (Barbier et al, 2011) such as ecological habitats and recreation areas. The first practical concept for predicting coastline change due to interruption of this wavedriven longshore transport was developed by Pelnard-Considère (1956), who derived a diffusion-type equation based on the assumptions of a small angle of incidence and a constant crossshore profile shape. The first very limiting assumption of a small wave angle was relaxed to some extent by numerical, onedimensional (1D) model approaches, such as GENESIS (Hanson, 1989), LITPACK (Kristensen et al, 2016), and UNIBEST (Tonnon et al, 2018) These models, which we will refer to as ‘standard 1D models’ applied increasingly powerful and more advanced physics-based approaches using newer transport formulations (e.g., Bijker, 1967; Kamphuis, 1991; van Rijn, 2014), to estimate the transport rate as a function of incident wave conditions, sediment parameters and profile shape. The nourishment work started just after the construction of the groin field and took six months to be completed
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
