Erosão costeira no litoral do município de Icapuí-Ce na última década: causas, consequências e perspectivas futuras

Abstract

The coastal erosion, as a result of a negative sediment balance, can be caused by natural and / or by anthropic factors and brings with it serious damage to the coastal environment, which is the target of various activities due to its strategic location. Due to this scenario, we analyze the evolution of coastal erosion in the municipality of Icapuí in the last decade through the reconstruction of past scenarios with newspapers in association with oceanographic databases to indicate the main causes of erosion. The topographic profiles and survey of the shoreline in each field experiment were performed using a DGPS receiver at the same time that sample sediment was collected. It was also analyzed the variation of the shoreline with satellite images between the years of 2002 and 2015, totaling 6 scenes analyzed. From the IPCC reports it was possible to establish scenarios related to sea level rise up to the year 2100. The results showed that coastal erosion became a problem in Icapuí when the number of constructions in areas very close to the coast located in the Beaches of Barreiras de Baixo and Barrinha. After its emancipation as a municipality, erosion worsened and became frequent in the news between 2011 and 2014, resulting in the scenario of destruction that entailed the installation of a series of containment measures in the area. The tide is the main coastal process in the monitored area, due to its amplitude that can reach 4 m, associated to the low slope in the beach range can reach areas more distant from the shoreline reaching the constructed built heritage and that becomes potentiated in periods of high energy events (i.g. stormsurges). The beach is mainly composed of fine and very fine sediments, due to the low energy of the environment in the intertidal zone and that can be easily transported by the flow of the tide. The fraction of larger particle size is concentrated mostly in the upper portion of the profiles, as a result of the direct action of the waves in the lower portion of the backshore in hightides and present high levels of calcium carbonate in its composition due to the presence of shells and rhodoliths. The analysis of the shoreline between 2002 and 2016 showed that in some stretches there was a general retrogradation of more than 90 m in 14 years between the Barreiras de Cima and Barrinha beaches, a fact enhanced by the construction of a rocky Beach of Barrinha. The constructions in the Beach of Barreiras de Cima are protected of the coastal erosion because they are located in the rear of frontal dunes, in addition, this stretch presents an extensive backshore. It was possible to verify that the entire stretch of the border of the municipality is vulnerable to a scenario of sea level rise due to its morphological characteristics, even in the more optimistic prognosis, thus evidencing a need for greater participation of the public power in measures that may help in the minimization of impacts caused by erosion and future problems related to climate change.