SATELLITE-BASED NEARSHORE SANDBAR DETECTION WITH IMPLICATIONS FOR BEACH CLASSIFICATION

Nearshore morphology, including sandbars, has a strong influence on coastal development. Despite their importance, these morphological features are well documented only at a few, but growing, hotspot beaches, despite their presence along important stretches of sandy coasts worldwide. Located in the surf zone, sandbars play a fundamental role in coastal dynamics by reducing the energy of incoming waves by acting as a temporary sediment reservoir and a mobile, flexible obstacle to waves and currents. Wright and Short (1984) established an initial coastal classification by defining a beach as reflective, dissipative, or intermediate based on observations of a large panel of single sandbar, microtidal coastal areas. Masselink and Hughes (2003) reclassified different types of beaches based on the amplitude of the tidal range. These morphologies are generally considered to be in equilibrium with tidal and wave forcing. However, the morphological response of the sandbar is generally longer than the time scales associated with changes in the wave regime. This reshaping is the main source of bathymetric profile variability on short intra- seasonal scale, mid-seasonal scale and long term inter- annual scale.