Process signatures in regional patterns of shoreline change on annual to decadal time scales

摘要

Gradients in wave-driven alongshore sediment transport influence the morphologies of sediment-covered coastlines on a range of spatial and temporal scales, affecting accretion and erosion patterns relevant to human development. Recent theoretical findings predict that a correlation between shoreline change and shoreline curvature results from patterns of alongshore sediment flux; the sign ( positive or negative) of that correlation depends on whether high- or low-angle waves dominated the wave climate. Using lidar surveys of the northern North Carolina coast from 1996-2005 to document shoreline change and quantify alongshore patterns of erosion and deposition, we isolate these signals diagnostic of alongshore-transport processes. Our analyses show a persistent, significant negative correlation between shoreline-position change and shoreline curvature consistent with a low-angle-dominated incident wave climate over the last decade. At large spatial scales, convex-seaward promontories have eroded landward, while concave-seaward bays have aggraded seaward, resulting in an apparent diffusion of alongshore morphological features.