O rio Urubu faz parte da bacia hidrográfica do rio Formoso, localizado no estado do Tocantins na região Norte do Brasil, sendo uma importante região agrícola e com forte utilização da irrigação para fortalecer a produção de arroz, cultivado na estação chuvosa, e em especial da soja para semente, durante a estação seca. A elevada dependência da irrigação associada a uma pluviosidade abaixo da média registrada no ano de 2016 que se estendeu pelos anos seguintes, ocasionou um período de escassez hídrica com impactos ambientais severos na bacia do rio Urubu. A disponibilidade hídrica na Bacia foi modelada com uso da ferramenta WEAP, com o objetivo de avaliar a necessidade de alteração das demandas de água para irrigação, buscando manter uma mínima vazão remanescente no rio Urubu. Para isso foram simulados cenários de redução percentual da vazão captada pelas bombas hidráulicas de irrigação. O período de análise foi de julho 2018 a junho de 2019 devido à restrição de disponibilidade de dados. Os resultados dos cenários indicam a necessidade de redução de 35% da demanda de referência para evitar uma interrupção na vazão do rio, sendo esse valor ainda maior na quando uma parcela dos agricultores não reduza o consumo. Para mudança da gestão dos recursos hídricos na bacia do rio Urubu, a participação dos diversos agentes se mostra fundamental, onde é preciso aumentar a eficiência na irrigação aliando alterações nos limites de outorgas de uso da água e aplicação de restrições de captação na estação seca.
Palavras-chave: análise de cenários; balanço hidrológico; modelo hidrológico
The Urubu River is part of the Formoso River Basin located in Tocantins State in northern Brazil. It is an important agricultural region where irrigation has an important role in rice and soybean crops, cultivated during the rainy and the dry seasons, respectively. The high levels of irrigation associated with below-average precipitation in 2016 and in the following years resulted in a water crisis in the Urubu Basin, with serious consequences to the environment and the economy of the region. This work evaluated the impact of reducing irrigation on environmental flows in the Urubu River Basin using hydrological modeling in WEAP. Irrigation water demand scenarios were simulated and analyzed from July 2018 through June 2019. Results indicated the need to reduce 35% of all water withdrawls in order to avoid the interruption of flow in the Urubu River Basin. This percentage was even greater when only some of the farmers cooperated. The paper emphasized that it is important that all farmers be involved and cooperate to reduce their water withdrawal by any means, including improving their irrigation system efficiency. The water regulator may also motivate water withdrawal reduction by modifying water permits and applying water withdrawal restrictions during the dry season.
Keywords: hydrological modeling, scenario analysis, water balance
The Urubu River is part of the Formoso River Basin located in Tocantins State in northern Brazil. It is an important agricultural region where irrigation has an important role in rice and soybean crops, cultivated during the rainy and the dry seasons, respectively. The high levels of irrigation associated with below-average precipitation in 2016 and in the following years resulted in a water crisis in the Urubu Basin, with serious consequences to the environment and the economy of the region. This work evaluated the impact of reducing irrigation on environmental flows in the Urubu River Basin using hydrological modeling in WEAP. Irrigation water demand scenarios were simulated and analyzed from July 2018 through June 2019. Results indicated the need to reduce 35% of all water withdrawls in order to avoid the interruption of flow in the Urubu River Basin. This percentage was even greater when only some of the farmers cooperated. The paper emphasized that it is important that all farmers be involved and cooperate to reduce their water withdrawal by any means, including improving their irrigation system efficiency. The water regulator may also motivate water withdrawal reduction by modifying water permits and applying water withdrawal restrictions during the dry season.
Keywords: hydrological modeling, scenario analysis, water balance
