Aplicação da modelagem Soil and Water Assessment Tool (SWAT) na Sub-Bacia Hidrográfica do Rio Jauruçu, Amazônia Paraense

Abstract

The sub-basin of the Jauruçu River, a tributary of the Xingu River, was chosen as the study area due to its socio-environmental relevance and the significant impacts caused by the expansion of agricultural activities, especially from the construction of the BR-230 (Trans-Amazonian Highway), which facilitated the process of occupation in the region. This process of converting large areas of forest into pastures has directly affected the hydrological cycle and the quality of water resources. To carry out this study, the SWAT model was used, which is a hydrological simulation tool that allows the evaluation of the impacts of land use and management practices on the hydrological cycle. The research covers a period of 30 years (1991-2021), focusing on the dynamics of land use and its effects on water balance, sediment production and environmental sustainability, this period allows the comparison of impacts over time. The results indicated significant transformations in the water balance of the sub-basin, with increased surface runoff, reduced evapotranspiration and increased sediment production. The average annual rainfall showed an upward trend, with peaks in specific years, possibly related to climate change and extreme events, something that should be analyzed more precisely. Evapotranspiration, although it presented similar values between 1992 and 2021, was influenced by vegetation cover and local climatic conditions, however, these results may be limitations of the model, it may be necessary to readjust the parameters of the variables. Surface runoff increased significantly, especially from 2009 onwards, reflecting the reduction of vegetation cover and the increase in soil impermeability, being directly related to agricultural activities. Sediment production also showed a significant increase, with peaks in years of extreme weather events, such as intense rainfall that occurs in a short period, which accelerated erosive processes. In summary, this study highlighted the importance of native vegetation for the balance of and regularization of the hydrological cycle of the sub-basin. It is evident the need for public policies and the implementation of sustainable management practices, and the incorporation of rainfall and fluciometric stations at strategic points of the sub-basin, in order to have a more detailed study of the climatic and fluvial elements of the region and the influence that on the water balance and other parameters, such as sedimentological and flow analyses in the sub-basin of the Jsuruçu River-PA. In conclusion, the work demonstrated the effectiveness of the SWAT model in the analysis of tropical watersheds, even under limited data conditions, and provided relevant subsidies for the sustainable management of water resources in the Amazon. The research reinforced the importance of forest conservation and reforestation strategies to mitigate the impacts of changes in land use and climate change.