MORPHODYNAMIC CHARACTERISTICS OF THE PÂNTANO DO SUL BEACH, SANTA CATARINA ISLAND, BRAZIL

Abstract

This work presents results of the analysis of morphodynamic characteristics of the Pântano do Sul Beach, a headland bay beach located at the southern shore of Santa Catarina Island. To achieve this purpose, three beach profiles located at different beach sectors were monthly monitored during a period of one year. Sediment samples were collected at the foredune basis, the backshore and at the beach face on each profile survey. There was also a survey in which sediment samples were collected along the whole beach within intervals of 200 m. The beach was classified according to the morphometric parameters and also using one morphological sequential model. In the northeast sector (profile 1), the beach has a permanent wave shadow zone. At this zone, the significant wave height seldom exceeds 0.5 m and the predominant morphodynamic stage can be classified as intermediate, so called low tide terrace (W = 1.44), even thought the grain diameter size is finer than at the other profile sectors. The mean wave energy increases towards the southward beach sectors (profile 2 and 3). Following this energy distribution, there was a rise in the sediment diameter size towards the southern sectors of the beach, and the morphology showed two wave breaker lines and rhythmic features like rips and beach cusps. The omega values associated with the central and southwest sectors (profiles 2 and 3) were 2.63 and 3.71, characterizing intermediate stages called “transverse bar and rip” and “rhythmic bar and beach”, respectively. As a general feature for Pântano do Sul, the predominant morphodynamic stage varied according to the incident wave energy along the different sectors of the beach. Low energy was associated to low tide terrace stage, moderate energy was correlated with transverse bar and moderate to hight energy with rhythmic bar.