Dinâmica da ocupação da terra e sua influência na suscetibilidade à erosão em Salinópolis - PA, Brasil.

Abstract

The socio-spatial configuration of a region is defined by the interests of individuals in the search for space and exploitation of resources, being determinants in the dynamics and established occupation patterns. Occupation, when associated with planning deficiency, occurs in a disorderly manner, generating impacts both on the environment, on the population and on the economy. In coastal areas, as in the municipality of Salinopolis-PA, these impacts gain a large proportion, like erosion processes, given the fragility of these environments. In the face of this context, this study aims to evaluate the dynamics of land occupation in the municipality of Salinópolis, based on the study of land cover and influential factors, and apply them to assess the susceptibility to erosion on the coast of Atalaia Island. For this, we sought to: a) analyze the spatio-temporal pattern of land occupation for the years 2010, 2014 and 2018, in the coastal and urban areas of Salinópolis; b) identify the factors that influence the dynamics of occupation in the municipality, using the Pressure-State-Impact-Response (PEIR) model; and, finally, c) analyze the susceptibility of erosive processes on the coastline of Atalaia Island based on spatial analysis of land occupation, topography and geoindicators, in order to generate susceptibility mapping. The spatial analysis showed excellent classification quality, with Global Accuracy index of 0.86 and Kappa index of 0.83, showing reductions in areas of dense, non-dense vegetation and dunes, and an increase in the urbanized area, mainly on Atalaia Island and towards the continent. The areas of water and beach strip showed dynamics marked by coastal factors. The main factors that influenced the observed occupancy patterns were: distance to the sea; distance to the PA-444 and PA-124 highways; road mesh density; distance to areas of greater real estate speculation; degree of implementation of projects; distance to consolidated urban patches; distance to areas of less real estate speculation; and distance to the center. The study area was classified as Low, Medium and High Susceptibility to coastal erosion. The results indicated a high susceptibility to erosion in the central region of the island, involving part of the Atalaia and Farol Velho beaches, where there is intense urbanization on the coastline combined with slopes greater than 15%, with evidence of active erosion. The low susceptibility class was predominant in the east of the island, in low slope areas, mostly below 5%, and with developed and stable dune fields. The areas of medium susceptibility were distributed in the transition between the low and high classes, presenting intermediate characteristics of slope and occupation, with the presence of partially altered and discontinuous dunes. In addition, it was possible to indicate areas with potential risk of increased susceptibility to erosion, in high-slope sectors where urbanization is close. The results of this study allow the private sector and the population in general to have one more tool for territorial and environmental management, allowing decision-making, which can mitigate or avoid the impacts that occur today on the coast of the municipality of Salinopolis.