Erosão costeira e suas implicações na praia de Morro Branco, Ceará, Brasil.

Abstract

Accelerated shoreline retreat is a major indicator of coastal erosion and can be used to define safe limits for land use and occupation in coastal regions. The objective of this work is to analyze the spatiotemporal evolution of the Morro Branco Beach coastline, 92 km from Fortaleza, between 2004 and 2019 in order to use it as a subsidy for the coastal planning of the region. The methodology consisted of a bibliographic, cartographic, legal survey (laws, guidelines, norms, among others) and news about erosive processes in popular information vehicles. Field trips were carried out in March, May and August 2019, to the detriment of seasonality, where six topographic monitoring profiles were made and measurements of the shoreline positioning in each one of them approximately 1.5 km long, where The acquired data were post processed in a software of the instrument itself. In addition, at the same time, 15 sediment samples were performed in each field, totaling 45. Field lines (3), Quickbard-type satellite images (5) and an orthophotochart were treated in GIS environment and then submitted to Digital Shoreline Analysis. System - DSAS version 5.0, where it was possible to assess the shoreline advances and setbacks of the last 15 years. Sediment samples were treated using the methodology of Suguio (1973). Morro Branco beach is in an erosive trend, where the three sectors (east, west and central sector) have rates ranging from -2.42 m / year to progradational trends that rarely exceed 0.20 m / year. The natural dynamics of the region, the disordered occupation of the soil and the presence of coastal geomorphological features are the main agents that contribute to such characterization. These declines were evidenced from news, especially from newspapers, that between 2011 and 2018 12 were recorded in total, with 2016 being the most recurrent due to the destruction of part of the built heritage installed in the coastal region. Faced with this problem, it was found that part of the coastal constructions are located in forbidden regions, at the municipal, state and federal levels, often in regions susceptible to the natural dynamics of the system, such as the stanza, base and top of the areas. Cliffs and surroundings with dunes. The data presented in this paper are essential to understand the natural dynamics of regions that have the peculiarities of the study area and, in addition, serve as a subsidy for the correct soil management and also the use of available natural resources.