Avaliação dos impactos sócio ambientais na bacia hidrográfica do Valão dos Bois em Seropédica-RJ

Abstract

The city of Seropédica, after the beginning of the works of the Raphael de Almeida Magalhães highway to BR 493 known as the Rio de Janeiro Metropolitan Arch in its territory, winning great regional visibility, due to its location attributes. Fridge to proclaimed certain of the municipal social growth, the clamor of administration for an industrialization process in its territory is not accompanied by a territorial planning that supports the future scenario of growth. This study produced quantitative data of interference in Valão dos Bois, which was used as a database of BOD5,20, COD, ST and OD, in computer simulation of self-purification processes. The rainfall, infiltration, runoff and leaching in four occupation areas of the urbanized watershed areas for rainfall with five distinct return phases. The result of measuring the morphometry of Valão dos Bois and its tributaries is the channel for large expansions, associated with a 50-year payback period. For example, in many stretches irregular occupations on its banks narrow the channel to favor flooding while ordinary rainfall precipitating. The analysis of water quality parameters revealed a high concentration of organic load in most stretches, especially those near urbanized areas. The results of the self-purification simulations revealed that sewage discharges continuously and spread throughout the Valão dos Bois, especially in the stretches close to the urbanized areas, increase the extent of the polluted stretch within the mixing and dilution process. Effluents called degradation and recovery zones respectively. The simulations of the occupation scenarios revealed that although the urbanized (more waterproofed) area of the Valão dos Bois watershed is very small, small increases in the waterproofing index greatly increase runoff rates and runoff peaks. Thus, in view of the expected population increase, we used the computer simulation of the implementation of infiltration trenches that, despite changing the sealed area of the municipality by 0.2%, was sufficient to reduce the peak flow rates between 8,5% and 206% in the different sub-basins. As of the 114 km² of the Valão dos Bois basin only 6km² are waterproofed areas, we find that for the less waterproofed sub-basins, the maintenance of the channels is sufficient to establish high water quality levels in the watercourses. For the sub-basins with the largest urbanized area (with the highest waterproofing index), a move towards establishing guidelines for the use and ordering of land occupation is recommended, avoiding the narrowing of drainage channels due to irregular occupation of its margins. non-structural control measures associated with measures such as the concentration of discharges at a specific point in each sub-basin avoiding the spreading of effluent discharge points, and the implementation of infiltration trenches as a complement to conventional drainage and sewage systems.