Environmental and anthropogenic indicators for coastal risk assessment at Massaguaçú Beach (SP) Brazil

Abstract

As a widespread trend, coastal erosion is occurring on many countries around the world. In general, such process is translated in environmental and socioeconomic damages in many coastal cities. The aim of this work is to use environmental and anthropogenic indicators to manage natural resources and subsidize regional planning. The study site is Massaguaçú Beach in Caraguatatuba, Northern Coast of São Paulo State, Brazil. The beach has been divided into three sectors and classified according to its risk in low, moderate and high. The indicators are beach profile, shoreline position, dune field, offshore settings, presence of rivers and/or inlets, terrain elevation, vegetation, coastal engineering structures, occupation rate and soil permeability. General information on these variables were extracted through remote sensing and geoprocessing techniques. The three beach sectors present different alongshore length, but a constant cross-shore distance of 500 m landwards from the water line. Sector 1, the southern part of the beach, is marked by the presence of the Massaguaçú River; sector 2, central part, concentrates the urban settlement; and sector 3, in the north, comprehends the Bracuí River and the landforms restricts the occupation in this area. Sectors 1 and 3 were classified as being of moderate risk, while sector 2 as being of high risk. Although the occupation rate is not too high, it has limited the beach profile and sediment budget. Any interventions in Massaguaçú should consider the sediment budget behavior and erosive trends.