Shoreline rate-of-change and setback line on adjacent areas of Sergipe river’s mouth, Aracaju, Sergipe

Abstract

The “Artistas” and “Atalaia” beaches, located in Aracaju, Sergipe, are subject to coastal processes (waves, currents and winds) and to Sergipe’s river mouth dynamics. From 2007 to 2008, severe erosive events, that led to the destruction of anthropogenic structures (events plaza, bars/restaurants, etc.), occurred on these beaches. This work aims to calculate the shoreline rate-of-change and the setback lines nearby Sergipe’s river mouth. The methodology consisted of: (i) historical analysis of shoreline positions using data from satellite images and beach profiles (from 2008 to 2015); (ii) calculation of the shoreline rate-of-change using the End Point Rate (EPR) statistics method; and (iii) determination of setback lines. Shoreline retreat rates in the investigated area, which ranged from -0.5 to -13 m/yr, allowed the establishment of two setback lines: 360 m for soft constructions and 730 m for hard constructions, respectively. The studied beaches present erosion protection structures, but they do not receive maintenance systematically. The erosion problem at some points was not solved definitively due to the recidivism of erosive events. Therefore, preventive measures, such as the use of setback lines recommended in this work, should be encouraged.