Study of the morphodynamic evolution of Cassino Beach dunes field through geotechnology

Abstract

Coastal systems are important socioeconomic and environmental areas, which are affected by a sort of natural processes of different temporal and spatial scales, becoming vulnerable areas. The dunes field are eolian landforms on sandy beaches that present functions such as protection of the shore and low adjacent regions. In this context the present work aims to measure the foredunes field evolution at Cassino Beach, Southern Brazil. The temporal analysis of a portion of the coast was based on Google Earth imagery from 2002, 2006, 2009 e 2012 and an aerial photograph registered in 1964, which were registered against a georeferenced and orthorectified image. Besides, the vectorization of the shoreline and foredunes field position was produced in a 1:1000 scale, suitable for the proposed goal. The quantification of advance and retreat rates of the foredunes field toward the mainland was performed according to the Change Polygon Methods. The results showed that over the years biomass has covering the dunes field, and in the last twelve years the rates have been lower. It was seen from 2006 to 2009 higher rates of biomass covering, especially compared to the previous (2002-2006) and later (2009-2012) periods, which is related to the decrease in the intensity and constancy of NE and E wind, main responsible for eolian transport.