Coastal vulnerability assessment based on video wave run-up observations at a mesotidal, steep-sloped beach

Coastal imagery obtained from a coastal video monitoring station installed at Faro Beach, S. Portugal, was combined with topographic data from 40 surveys to generate a total of 456 timestack images. The timestack images were processed in an open-access, freely available graphical user interface (GUI) software, developed to extract and process time series of the cross-shore position of the swash extrema. The generated dataset of 2% wave run-up exceedence values R 2 was used to form empirical formulas, using as input typical hydrodynamic and coastal morphological parameters, generating a best-fit case RMS error of 0.39 m. The R 2 prediction capacity was improved when the shore-normal wind speed component and/or the tidal elevation η tide were included in the parameterizations, further reducing the RMS errors to 0.364 m. Introducing the tidal level appeared to allow a more accurate representation of the increased wave energy dissipation during low tides, while the negative trend between R 2 and the shore-normal wind speed component is probably related to the wind effect on wave breaking. The ratio of the infragravity-to-incident frequency energy contributions to the total swash spectra was in general lower than the ones reported in the literature E infra/E inci > 0.8, since low-frequency contributions at the steep, reflective Faro Beach become more significant mainly during storm conditions. An additional parameterization for the total run-up elevation was derived considering only 222 measurements for which η total,2 exceeded 2 m above MSL and the best-fit case resulted in RMS error of 0.41 m. The equation was applied to predict overwash along Faro Beach for four extreme storm scenarios and the predicted overwash beach sections, corresponded to a percentage of the total length ranging from 36% to 75%.info:eu-repo/semantics/publishedVersio

Self-organization of a biogeomorphic landscape controlled by plant life-history traits

Feedbacks between geomorphology and plants are increasingly recognized as key drivers shaping a variety of landscapes. Most studies of biogeomorphic interactions have focused on the influence of physical plant characteristics, such as stem and root density, on landscape morphodynamics without considering the role of life-history traits. However, pioneer plants can have very different colonization behaviours. Fast colonizers are characterized by a high number of establishing seedlings that produce homogenous vegetation patterns. In contrast, slow colonizers are characterized by a low number of establishing seedlings that are able to expand laterally, resulting in patchy vegetation patterns. Here we combine biogeomorphic model simulations and field observations in the Western Scheldt Estuary, the Netherlands, to show that colonization behaviour can influence the evolution of wetland landscapes. We find that colonization by fast colonizers favours stabilization of pre-existing channels and consolidation of the landscape configuration. In contrast, colonization by slow colonizers facilitates the formation of new channels and thereby actively facilitates further landscape self-organization. Our findings underline the key role of life-history traits in steering landscape self-organization across different biogeomorphic systems, and potentially the long-term resilience of these landscapes to disturbances