Quantificação da carga de poluição difusa e pontual como ferramenta para planejamento no alto curso da bacia hidrográfica do rio Manhuaçu

Abstract

Understanding the influences of soil use and occupation on water resources is a challenge faced in last years. Brazilian water resources management develops over time supported by a very strong legal basis, but without integration with territorial development, negatively impacting water resources. Mathematical modeling, mainly associated with Geographic Information Systems (GIS), appears in this context as an extremely important tool in the water resources management process, as it can contribute from diagnosis to the choice of management and intervention alternatives. The objective of this research was to quantify the generation of diffuse and punctual loads of parameters N, P and BOD 5.20 in the contribution basin of the Upper Course of the Rio Manhuaçu using the mathematical model MQUAL 2.0. For this purpose, soil use and occupation maps from 2008 to 2018 were prepared and the mathematical model was calibrated and validated with flow data and quarterly water quality reports from IGAM. Based on this, 6 (six) scenarios were studied over a 20 (twenty) year horizon. With the mapping of the soil cover, it was observed a possible substitution, mainly of the capoeira and field areas by agricultural activity, which would increase the exportation in 0.067 kg / km².day of Total Phosphorus; 0.177 kg / km².day of Total Nitrogen and 3,838 kg / km².day of BOD 5.20. The scenarios showed that sewage treatment should be prioritized in the basin, but the association of sewage treatment with the restoration of APP's would bring a reduction in exports of 93.44% of P load, 83.25% of N and 82, 08% BOD 5.20 by the year 2040. The calibrated coefficients will serve as a basis for future studies in the basin, which still has few published works, and the scenarios are important sources of support for the river basin committee to choose the projects priorities, which will be leveled in the basin, and the effective results for the qualitative and quantitative improvement of water resources.