Predicting Climate‐Driven Coastlines With a Simple and Efficient Multiscale Model

Abstract

Ocean‐basin‐scale climate variability produces shifts in wave climates and water levels affecting the coastlines of the basin. Here we present a hybrid shoreline change—foredune erosion model (A COupled CrOss‐shOre, loNg‐shorE, and foreDune evolution model, COCOONED) intended to inform coastal planning and adaptation. COCOONED accounts for coupled longshore and cross‐shore processes at different timescales, including sequencing and clustering of storm events, seasonal, interannual, and decadal oscillations by incorporating the effects of integrated varying wave action and water levels for coastal hazard assessment. COCOONED is able to adapt shoreline change rates in response to interactions between longshore transport, cross‐shore transport, water level variations, and foredune erosion. COCOONED allows for the spatial and temporal extension of survey data using global data sets of waves and water levels for assessing the behavior of the shoreline at multiple time and spatial scales. As a case study, we train the model in the period 2004–2014 (11 years) with seasonal topographic beach profile surveys from the North Beach Sub‐cell (NBSC) of the Columbia River Littoral Cell (Washington, USA). We explore the shoreline response and foredune erosion along 40 km of beach at several timescales during the period 1979–2014 (35 years), revealing an accretional trend producing reorientation of the beach, cross‐shore accretional, and erosional periods through time (breathing) and alternating beach rotations that are correlated with climate indices.

Uncertainties in projections of sandy beach erosion due to sea level rise: an analysis at the European scale

“…Long-term changes in shoreline position can be expected in response to long-shore sediment transport gradients 22,31,47 . Additionally, the presence of sediment sources/sinks 37,48 and any residual effects of storms and others seasonal, annual or multi-annual fluctuations 49 can lead to additional shoreline changes 22,25,31,37,48 . In the work herein, we focused on the shoreline retreat that is directly driven by SLR, omitting the uncertainty related to the aforementioned additional processes.…”

Steps to Develop Early Warning Systems and Future Scenarios of Storm Wave-Driven Flooding Along Coral Reef-Lined Coasts

“…Such models also need to include anthropogenic interventions such as engineering structures that impact upon future shoreline development. Recently, long-term shoreline evolution models have been developed for open-coast sandy beaches with simple configurations (e.g., Vitousek et al, 2017b;Robinet et al, 2018;Antolínez et al, 2019), yet, few studies (e.g., de Alegria-Arzaburu et al, 2013) exist for coral reef-lined beaches, especially at longer time scales. While existing studies of wave-driven evolution of perched beaches might represent a suitable proxy for reef-lined coasts either the dimensions of the submerged barriers are not consistent with coral reefs (e.g., González et al, 1999), the potential effect of infragravity waves has not been considered and/or they provide only conceptual models (e.g., Gallop et al, 2012).…”

Blind testing of shoreline evolution models

“…Other longshore transport models 11 have been applied to long term datasets but lacked the ability to reproduce cross-shore variations 30 . This issue was recently addressed [31][32][33] , where alongshore sediment transport formulae such as, CERC 34,35 are combined with cross-shore equilibrium models. Table 1 provides a summary of the HM used during the Shoreshop.…”