No abstract

Agriculture is the economic activity which uses water the most in Brazil, particularly in São Francisco River Basin, where water withdrawals for irrigation granted by water authorities amount to 22.3 billion m3 per year, a number which is close to 81% of the total withdrawal. On the other hand, bulk water in Brazil is underpriced. Water charges for agricultural users neither reflect the economic value of water nor induce a rational and efficient use of water resources, two key concepts of the Brazilian water law. Even so, it is common for irrigators to complain about the water prices charged for their use of bulk water. To throw some light on the real impact of charging water in the agriculture sector, this article evaluates the economic value of irrigation water in the São Francisco River basin through the shadow price approach, calculated by using the Residual Value Method. The analysis was performed for the top ten major São Francisco River basin crops in water use terms, namely corn, soybean, mango, beans, coffee bean, banana, cotton, sugar cane, papaya and rice. Results for the 2019 harvests show that except for sugar cane, all water shadow prices were positive, notably mango, beans and papaya. This paper also evaluated water shadow prices interannual variation from 2014 to 2019 for six crops. Except for sugarcane, the other crops have been profitable most of the time in the last 6 years. A wide fluctuation in the shadow price of water was observed over these years due to variations in sales prices and costs of production.

É notório a preocupação com o abastecimento de água no mundo, já que este é um recurso finito. A falta de chuva, principalmente na região Nordeste, aliada com a degradação ambiental dos nossos cursos d’água, vem contribuindo ainda mais para o agravamento dessa crise. Sendo assim, objetivou-se com este trabalho identificar as nascentes afluentes do Rio Piauí em Alagoas nas porções média e baixa de sua bacia hidrográfica, realizando seu georreferenciamento e em seguida uma análise macroscópica de cada nascente. O diagnóstico foi realizado nos meses de agosto, setembro e outubro de 2015, foi realizado um levantamento de todas as nascentes dessa região hidrográfica e as mesmas foram qualificadas de acordo com seu grau de preservação. Para a realização dessa qualificação, foram realizadas visitas in loco a essas nascentes e através do preenchimento de uma ficha, juntamente com o somatório dos pontos, foi possível classificar o grau de preservação de cada nascente. O relatório ambiental mostra uma situação preocupante do ponto de vista macroscópico, pois, nenhuma das nascentes diagnosticadas, foi classificada em um ótimo grau de preservação, e mais de 70% delas foram classificadas em um estado de preservação ruim a péssimo.

The land use characteristics of rural watersheds allow infiltration and consequent generation of groundwater flow, which constitutes a significant contribution to the hydrograph. Prior to this study, the MODCEL-COPPE/UFRJ model simulated only runoff, disregarding the losses occurred in rainfall-runoff process. Therefore, its application was more appropriate to urban watersheds, simulating flood events where surface flows prevail. This study aimed at representing the infiltration process and at incorporating the groundwater flow in the MODCEL’s structure, making feasible the rural watersheds simulation thus expanding its applicability as a hydrological model. A case study was performed in a 417 km2 subcatchment of Piabanha River, located at Petrópolis/RJ. It’s a predominantly rural watershed, with 80% of its area covered by forests. The model represented satisfactorily the seasonality and the magnitude of simulated recharges. In the parameter calibration procedure gave a coefficient of determination R2 = 0.75, comparing the calculated flows to the observed flows. During validation period, we obtained a coefficient of determination R2 = 0.76. The fit obtained was superior to that obtained in previous modeling of the same watershed by SMAP and MODCEL (previous version) and it was similar to TOPMODEL. In the hydrograph recession, new MODCEL presented R2 = 0.75, against 0.52 obtained in its previous version.