Avaliação experimental de métodos de armadilhas de sedimentos para determinação do transporte costeiro da praia da Romana, ilha dos Guarás (nordeste do Pará)

Abstract

The Romana Beach is ruled by waves, with an average height of 1,5 m, winds (average of 4,6 m/s) predominantly from the NE and semidiurnal meso-macrotidal (ranging from 4,3 m - march/2010; 3,4 m - august/2010). The methodology consisted of sediments samples with traps and intensity measurements of longshore currents and local winds during the months of january, march and august 2010. In the wind traps, the accumulated weight of sediments was very low, ranging from 0,02 g to 0,8 g (maximum occurred in August in the eastern sector, as well as the wind speed: 6,7 m/s). Larger quantities of sediment were collected from the eastern to the western sectors, coinciding with the prevailing wind direction (NE), whose maximum speed occurred in august (6.7 m/s in the eastern sector). In the portable traps, the minimum weight occurred in march (eastern sector, ebb tide: 0,74 g/h/m3), and the maximum in january (central sector, rising tide:139 g/h/m3). The intensity of the longitudinal currents ranged from 0,20 m/s (ebb tide) to 1,41 m/s (rising tide). It was concluded that the largest forcing of sediment transport on the beach is the flood tide current, which intensifies the longitudinal currents from the eastern to the west sectors. Secondly, the NE winds which minimize the loss of sediments on the beach, especially in the central and eastern sectors. Then the waves, maintain the direction of E-W transport because to their incidences on the coast with direction NE.