The study found that the western ends of these beaches have been steadily growing, or accreting, at a rate of about 4 meters per year. This trend is attributed to net westward longshore drift, a process driven by ocean currents that move sediment along the coastline. Meanwhile, the central sections of the beaches, particularly areas with groin fields—structures designed to trap sand—showed slower rates of shoreline change, typically between 0.5 and 1.5 meters per year.
One notable observation was the presence of so-called sediment waves, or patterns of erosion and accretion lasting several years, moving westward along the shoreline during the study period. Beach nourishment projects, where sand is added to counteract erosion, were shown to temporarily accelerate shoreline growth, often followed by significant retreat in subsequent years. These sediment waves highlight the dynamic interplay between natural processes and human interventions.
The study achieved its results without fieldwork, relying solely on decades of satellite data. The findings demonstrate how satellite imagery can offer a detailed view of geographic and temporal variations in shoreline change. These data improve scientists’ understanding of how natural phenomena, such as longshore drift, and human activities, including the construction of jetties and groins and sediment dredging, shape these highly visited and densely populated coastlines.
