Morfodinâmica e caracterização geoambiental na planície costeira do município de Marechal Deodoro, Alagoas

Abstract

Given the need to expand the knowledge of the physical environment in order to establish rational guidelines for the use of coastal areas in the state of Alagoas, the present research aimed to analyze the morphodynamic characteristics, vulnerability to erosion, sedimentology, use and occupation of the land and the geoenvironmental changes in part of the coastal plain of the Marechal Deodoro county. Therefore, the study area was delimited along the coast line and the AL-101 South. The methodology was based on two stages: the field stage, which consisted of carrying out on-the-spot data surveys over the years 2018 to 2019; and laboratory tests, through the analysis of primary and secondary data and consequent determination of results. Thus, four sectors were defined for the area, defined as P1, P2, P3 and P4. In the first sector Profile 1 (P1) located at Saco da Pedra beach, P2 (Maré Restaurante), P3 (Hotel Ponta Verde) and P4 (Leprosário region) located at Francês beach. After due analysis, we verified that the population growth of the last decades in the coastal plain of the municipality has led to the conurbation process in parallel to the capital of Alagoas, with serious problems of disordered urbanization, deficiency in the collection of solid residues, collection and treatment of sanitary effluents, in addition to marine erosion and inefficient urban drainage. The coastal circulation is related to winds and tides, such as seasonal variations. The Profile P1 showed deposition in october/2018, even on the beach that is in the process of anthropic erosion, due to the occupation of the sector by the Saco da Pedra condominium; Profiles 2 and 3 detected chemical erosions and P4 is more stable and with typical preserved vegetation. The granulometric analyzes for sectors P1, P2 and P3 showed alternation of medium and fine sand and for P4, fine sediments predominated. And that environmental vulnerability is related to changes and degradation of ecosystems, in P1 the vulnerability was considered high, with no post-beach, intense and consolidated anthropic occupation, reduced styrenium, degradation of native vegetation and waterproofing of marine terraces, due to occupation, which alters the sediment movement regime. At points P2 and P3 (center of Francês beach) the vulnerability was considered average, due to the level of waterproofing of the post-beach by urbanization and the installation of containment works on the coastal cordon, in P4, located further south, vulnerability is low, as distinct from the previous sectors, the beach is well consolidated and the post-beach has strands covered by typical vegetation and has no buildings. From the geo-environmental zoning, we found that the main environmental problems are related to occupations, as well as potential risks such as cemetery, ice factory and gas stations. Thus, it was found that the area under study is formed by a dynamic environment in a situation of fragility resulting from the natural characteristics and the pressures exerted on them. And, that there is an urgent need for sustainable actions that enable the preservation and recovery of natural environments on the coastal plain.