Morphological and sedimentological variation along an annual cycle in a sandy beach in south Brazil

Abstract

An analysis of the beach morphodynamics and its relationship with the sedimentological variation throughout a year, in Atami beach, Paraná, South Brazil, is presented. Sample stations were distributed along a transect from the upper beach face to the nearshore (-3 m). Sediment was obtained with a corer and treated in laboratory by sieving. For a morphodynamic beach characterisation, wave height and period values were used for calculated the dimensionless fall velocity parameter (?) and the surf scaling parameter (ø). The beach presented an intermediate morphodynamic state only during some spring and summer months, being dissipative in the others. Significant variation of the beach morphology was observed during the year, specially in the sub-aqueous beach, where periods of sand bar construction prevailed in the summer and destruction occurred mainly in the winter. Atami beach sediments are typically very well sorted, fine and very fine sands (ø 3 - 4), composed mainly by quartzo Sediment distribution along the profile varied considerably. A great yearly variation was presented in the sub-aqueous beach's sediments, with skewness and sorting values related to the morphological variations. More detailed information about the sediment behaviour along the all beach profile is needed for a completed description of this particularly environment.