Beach morphological variations over micro-time scales

Abstract

Nature and magnitude of beach changes over short periods have been studied at Calangute and Miramar in relation to tide, ground water level and relevant oceanographic and meteorological factors. Alternating zones of accretion and erosion moving up and down the beach face with breakers, locations of which alternately shift landwards and seaward with the rise and fall of tide are observed. The ground water table shows an oscillation with tide with a time lag of about 1 hr. When the ground water table cuts across the beach face, erosion processes become prominent. Short-term erosion and accretion patterns are discussed in terms of the short-crested wind waves and low long period swells prevailling in different seasons. During the periods of cusp formation, variations in the profiles show anomalous behaviour. The different in grain-size distribution of the sediments of these 2 beaches are attributed to the available wave energies at these 2 locations.