Fragilidade ambiental na sub-bacia hidrográfica do rio Araçagi-PB: subsídios para o planejamento ambiental

Abstract

Human activities have contributed to the increase in environmental imbalances. Considering that a large part of the world's population is concentrated along river banks, these imbalances have affected the availability of water for human beings, given the weaknesses presented by these environments. In view of the above, this dissertation has the general objective of making an assessment of the environmental weaknesses existing in the Araçagi-PB river sub-basin, based on two different methodologies. The specific objectives were: Assess potential fragility with data from the physical and biotic environment and based on the methodology of Ross (1994); evaluate the emerging fragility caused by human action, based on the methodology of Ross (1994); analyze environmental fragility, based on the potential for soil losses, using the Universal Soil Loss Equation (EUPS); compare the environmental fragility generated with the two methodologies; propose environmental management and planning measures with the aim of minimizing problems arising from weaknesses identified in the Araçagi-PB sub-basin. Using Ross' methodology, several weaknesses were identified in the Araçagi River sub-basin. In the upper reaches, the dams made to provide water for cattle stand out, with the spring being an area that was heavily deforested to make way for pastures. In the middle course, superficial linear erosion processes occur, such as erosion grooves and ravines in areas of greater slope. In the lower reaches, use is more intense, which means that this area is heavily deforested, to make way for urbanization and other diverse uses, whether industrial or agricultural. It is important to highlight that there are still remnants of vegetation in part of the basin, which means that fragility does not reach very high levels. With this, it was possible to see that most of the basin has a high rate of fragility. Using the EUPS, soil losses were identified in the Araçagi River sub-basin, noting that they occur mainly in areas with greater slope. The geometry of the slopes also plays a fundamental role, since on concave slopes losses occur more significantly, while on more convex slopes losses are lower. Thus, a large part of the sub-basin showed low soil loss, with the greatest losses being in the northern portion, in the middle course. Therefore, through this study it was found that the two methodologies showed that there are weaknesses in the sub-basin, although different levels predominate. In both cases, weaknesses were observed in a large part of the basin, but not at very critical levels. The reality of the sub-basin shows that there is still possibility for environmental agencies to act, with environmental management and planning measures, in order to alleviate environmental problems, preventing more serious problems from occurring.