The land–sea coastal border: a quantitative definition by considering the wind and wave conditions in a wave-dominated, micro-tidal environment

Abstract

Abstract. A quantitative definition for the land–sea (coastal) transitional area is proposed here for wave-driven areas, based on the variability and isotropy of met-ocean processes. Wind velocity and significant wave height fields are examined for geostatistical anisotropy along four cross-shore transects on the Catalan coast (north-western Mediterranean), illustrating a case of significant changes along the shelf. The variation in the geostatistical anisotropy as a function of distance from the coast and water depth has been analysed through heat maps and scatter plots. The results show how the anisotropy of wind velocity and significant wave height decrease towards the offshore region, suggesting an objective definition for the coastal fringe width. The more viable estimator turns out to be the distance at which the significant wave height anisotropy is equal to the 90th percentile of variance in the anisotropies within a 100 km distance from the coast. Such a definition, when applied to the Spanish Mediterranean coast, determines a fringe width of 2–4 km. Regarding the probabilistic characterization, the inverse of wind velocity anisotropy can be fitted to a log-normal distribution function, while the significant wave height anisotropy can be fitted to a log-logistic distribution function. The joint probability structure of the two anisotropies can be best described by a Gaussian copula, where the dependence parameter denotes a mild to moderate dependence between both anisotropies, reflecting a certain decoupling between wind velocity and significant wave height near the coast. This wind–wave dependence remains stronger in the central bay-like part of the study area, where the wave field is being more actively generated by the overlaying wind. Such a pattern controls the spatial variation in the coastal fringe width.

Potential of Transplanted Seagrass Meadows on Wave Attenuation in a Fetch-Limited Environment

“…Finally, this area is a fetch-limited and a micro-tidal environment, with mixed tides predominantly semidiurnal and tidal ranges of about 20 cm [96].…”

CMEMS-Based Coastal Analyses: Conditioning, Coupling and Limits for Applications

“…This combination requires an objective definition of what is the coastal zone, understood as a region where land and marine factors influence the domain dynamics, defining its boundaries in terms of the covariance anisotropy. Because of the land-water boundary, the coastal zone has been defined (Sánchez-Arcilla et al, 2019) as the region where covariance for key metocean variables is clearly anisotropic. The key variables selected include significant wave height, wind velocity or current velocity, both from predicted and measured fields.…”

“…Sentinel altimetry, in its early stages, provided only limited size samples, hampering the derivation of statistically significant conclusions on spatial error structures. The effects of geometry (topography and bathymetry) on error structures has become apparent from the different pilot cases, pointing at the need to consider coastal zone geometry and variance intensity (Sánchez-Arcilla et al, 2019), as a function of coastal distance to assess error structures. In spite of such limitations, the decreasing return cycle of Sentinel (for instance, S1 sea surface velocity data with a return cycle of 12 days) has allowed an assessment of spatial distributions, even though the intertidal time scales (e.g., North Sea pilot cases) cannot be resolved.…”

Land–Sea Interaction: Integrating Climate Adaptation Planning and Maritime Spatial Planning in the North Adriatic Basin

“…To aid the LSI approach, the framework considers the necessary physical and spatial characteristics needed to develop an integrated, transboundary planning approach. The land-based analysis focuses on the morphological characteristics of a coastal buffer, according to coastal adaptation concepts [33,65]. This is useful to recognize and quantify different settlement typologies.…”