Vulnerabilidade ambiental da bacia hidrográfica do Rio Pindaré – MA

Abstract

This research aims to analyze environmental vulnerability in the Pindaré river basin – MA, considering the use and land cover there between the years 1991 to 2021. To achieve the proposed objective, bibliographic research was carried out; selection of cartographic bases; application of geoprocessing techniques to produce thematic maps, using a scale of 1:250,000; and the use of the QGIS Geographic Information System. As a methodological path, we used Crepani et. al. (2001) to obtain vulnerability factors, where the different degrees of vulnerability prevalent in the Pindaré river basin were assessed, based on three types of environments considered as environmental units, namely: stable environments, in which pedogenesis prevails; intergrade environments, in which there is a balance between pedogenesis and morphogenesis; and those that are highly unstable, in which morphogenesis predominates. The final results made it possible to identify that regarding the stable aspects of the Pindaré river basin, the watercourses and areas located in the southern part of the basin, where welldeveloped soils were identified, with the presence of remaining vegetation cover, low rate of erosive potential energy of the relief, in addition to, for the most part, stable levels of rainfall intensity, correspond to environments with the occurrence of the pedogenesis process. As for the landscape units considered vulnerable, the greatest predominance was found in the north of the basin, with the presence of the lithostratigraphic units Alluvial Deposits, Wetland and Mangrove Deposits and Fluvio-lagoon Deposits, characterizing, in addition to the presence of poorly developed soils, also an intense process of water retention and difficulties in surface runoff, such as the multiple classes of plintosols. In the central areas of the basin, high levels of potential erosive energy of the relief were identified, in relation to declivity and horizontal and vertical dissections, in addition to high variations in rainfall intensity in 1991. Furthermore, the use and cover of the land demonstrated is intense in these regions, covering mainly pasture and monocultures, damaging the natural vegetation cover. Finally, the Pindaré river basin presented multiple processes of modification of its landscape units, which are more stable in the south, intergrade in the center and vulnerable in the north. Such information is encouraged in view of the growing process of agricultural and urban development in the region in the last thirty years, in addition to the unrestrained use of natural resources and suppression of vegetation, activities that contribute to the growing state of environmental vulnerability in the area, providing each increasingly scenarios of catastrophic events for the environmental characteristics of the Pindaré river basin.