Search

Time-frequency techniques to characterize cuspate patterns in light detection and ranging (lidar) data are introduced using examples from the Atlantic coast of Florida, United States. These techniques permit the efficient study of beach face landforms over many kilometers of coastline at multiple spatial scales. From a lidar image, a beach-parallel spatial series is generated. Here, this series is the shore-normal position of a specific elevation (contour line). Well-established time-frequency analysis techniques, wavelet transforms, and S-Transforms, are then applied to the spatial series. These methods yield results entirely compatible with the traditional method of estimating the spacing of cuspate features. In addition, confidence intervals are readily established for the spatial extent and wavelengths of cuspate landforms simultaneously at multiple scales. Examples show this method is useful for capturing transitions in cuspate shapes. With the advent of land-based time-lapse lidar, such techniques should be particularly useful for characterizing the evolution of cuspate landforms and testing models for beach face dynamics. [ABSTRACT FROM AUTHOR]

Abstract: Morphological observations (terrestrial laser scanning) and sediment analysis are used to study beach cusp morphodynamics at Melbourne Beach (Florida, USA), a moderately sloped beach characterized by fine sand. The study couples rapid high-resolution surveying with surficial sediment sampling over multiple tidal cycles. Surveys were run ~500m alongshore and sediment samples were collected intertidally over a period of 5days. Beach cusp location within larger scale beach morphology is shown to directly influence cusp growth as either gross erosional or gross accretional. Sediment characteristics within the beach cusp morphology are reported coincident with cusp evolution. Variations in particle size distribution kurtosis are exhibited as the cusps evolve, however no significant correlation is seen between grain size and position between horn and embayment. During the end of the study, a storm resulted in beach cusp destruction and increased sediment sorting. [Copyright &y& Elsevier]