Balanço hídrico quantitativo das águas superficiais na bacia hidrográfica do Rio Jaguarão

Abstract

Water resources are one of the most important natural resources in the world, making it essential to protection and guarantee better quality and quantity. Thus the knowledge of the behavior and changes that influence the waters present in the hydrographic basins is extremely important for an efficient management considering their multiple uses. Based on these claims, the present study aims to quantitatively analyze the water resources of the transboundary basin of the Jaguarão River (BJR), which is located on the border between Brazil and Uruguay. More specifically, the objective of this work was to apply mathematical modeling tools, expressed in the Large Basin Hydrological Model (BHM) and WARM-GIS Tools, both models developed by the Hydraulic Research Institute (HRI) of the Federal University of Rio Grande do Sul (FURGS), in an attempt to carrying out the hydrological modeling and quantitative water balance of water resources, respectively. Three scenarios were developed, on a monthly and annual basis, adopting Q90 as a reference flow rate, and thus, the water stress index (WSI) was represented for each section of the BHRJ drainage network, with emphasis on analysis of the multiple uses of water influence in the basin, especially for irrigation purpose. In addition, in order to improve the quantitative representation of water for the BJR, the Water Commitment Index (WCI) and the Water Withdrawal Index (WWI) were applied to diagnose the water scarcity level of the basin considering the annual water commitment. The results of the hydrological modeling carried out using the MGB showed that, in general, the model presented a good performance in both in calibration and validation of the periods adopted. The WSI representation WSI showed that in the current scenario the basin suffers from high water stress in the months that comprise the summer season (January, February, March and December), furthermore, the application of the WSI exposed the great influence of water use on irrigated rice in the region. The WCI has reinforced this result, as it presented sub-basins that fit into a critical situation, requiring intense management activity and large investments.