Assessment of conflicts between mangroves and human occupation in Subaé river outfall between the years 1988 to 2017

Abstract

Coastal zones fulfill important ecological, social and economic functions. Because soil flooded by tidal variations and due to great variation in salinity. Mangroves cover these regions. They are also a tropical coastal ecological system, always in the lowlands, at the mouths of rivers and estuaries. Despite their important environmental role, mangrove areas have been continuously decreasing worldwide, with an average reduction of 30% in the last 30 years. Thus, this research sought to determine land use and land cover change in low Subaé. With emphasis on Mangrove areas and urban occupation. We used supervised classifications of satellite images to evaluate the changes. We chose images from 1988, 2003, and 2017. And used images from the Landsat series (30m) and an image from the PlanetScope satellite (3m). We validated classifications through the Tau and Geographical Simultaneity concordance measures. We observed that performing the spatio-temporal analysis observing only the variation of areas may not represent the phenomena that occurred. The overall Tau index calculation for the ratings was 0.89. During the period 1988-2017 there was a significant reduction in Agricultural areas, corresponding to around 15% of the study area. Meanwhile, growth of pasture from 24km² to 48Km² and the Urban Zone, occurred over all classes, including mangroves.