Micro reservoirs and runoff in the Itaim basin in Taubaté, SP, Brazil ; Micro reservatórios e escoamento na bacia do Itaim em Taubaté, SP, Brasil
Urbanization of the watersheds in developing countries is generally accelerated and disorderly. The urbanization process generates soil impermeability, which impedes the infiltration of rainwater, accelerating surface runoff to favor accumulation of water at the lowest points, causing flooding. The construction of micro reservoirs for rainwater storage and infiltration within residential areas can minimize flood problems. In the present study, the effective precipitation and its reduction in the Itaim stream basin in the city of Taubaté, SP, were estimated by usage of 3400 and 6800 liters micro reservoirs to capture water on 125 m² roofs in different soil occupations, according to the Law 412/2017 of the Master Plan of Municipal Physics of Taubate (PDFMT). Effective precipitation was estimated using the curve number (CN) method, while variation in land use and occupation considered the land area in accordance with current legislation, with urban expansion at 50 and 100% over the macrozone rural, as well as 100% urban consolidation. The results showed that surface runoff (Pe) in the Itaim basin increases with the expansion of the urban area, as well as urban consolidation. The use of micro reservoirs considerably reduces runoff volumes. The micro reservoir, with a storage volume of 3400 liters, made it possible to restrict the flow promoted by rain of up to 25 years of return period, simulating the urban expansion of 50% over the rural area, while the reservoir with 6800 liters in capacity contains rain of up to 200 years return period for the same simulation condition. Although this type of structure was not considered in the municipal land use and occupation law, this study demonstrates that the use of hydraulic systems or elements with potential to reduce runoff can be an important means to ensure the sustainability of urbanization. of watersheds with planned stormwater disposal. ; Urbanization of the watersheds in developing countries is generally accelerated and disorderly. The urbanization process generates soil impermeability, which impedes the infiltration of rainwater, accelerating surface runoff to favor accumulation of water at the lowest points, causing flooding. The construction of micro reservoirs for rainwater storage and infiltration within residential areas can minimize flood problems. In the present study, the effective precipitation and its reduction in the Itaim stream basin in the city of Taubaté, SP, were estimated by usage of 3400 and 6800 liters micro reservoirs to capture water on 125 m² roofs in different soil occupations, according to the Law 412/2017 of the Master Plan of Municipal Physics of Taubate (PDFMT). Effective precipitation was estimated using the curve number (CN) method, while variation in land use and occupation considered the land area in accordance with current legislation, with urban expansion at 50 and 100% over the macrozone rural, as well as 100% urban consolidation. The results showed that surface runoff (Pe) in the Itaim basin increases with the expansion of the urban area, as well as urban consolidation. The use of micro reservoirs considerably reduces runoff volumes. The micro reservoir, with a storage volume of 3400 liters, made it possible to restrict the flow promoted by rain of up to 25 years of return period, simulating the urban expansion of 50% over the rural area, while the reservoir with 6800 liters in capacity contains rain of up to 200 years return period for the same simulation condition. Although this type of structure was not considered in the municipal land use and occupation law, this study demonstrates that the use of hydraulic systems or elements with potential to reduce runoff can be an important means to ensure the sustainability of urbanization. of watersheds with planned stormwater disposal. ; A urbanização das bacias hidrográficas dos países em desenvolvimento é geralmente acelerada e desordenada. A urbanização gera impermeabilidade do solo, o que evita a infiltração de água da chuva no solo e acelera o escoamento superficial, favorecendo o acúmulo de água nos pontos mais baixos, causando inundações. A construção de micro reservatórios para armazenamento de água da chuva e infiltração em áreas residenciais pode minimizar os problemas de inundação. No presente estudo, a precipitação efetiva e sua redução na bacia do rio Itaim, na cidade de Taubaté, SP, foram estimadas devido ao uso de micro reservatórios de 3400 e 6800 litros para captar água em telhados de 125 m² em diferentes usos do solo conforme definição da Lei 412/2017 do Plano Diretor de Física Municipal de Taubaté (PDFMT). A precipitação efetiva foi estimada pelo método do número da curva (CN) e a variação no uso e ocupação da terra considerou a área de terra de acordo com a legislação vigente, com expansão urbana de 50 e 100% sobre a zona rural da macrozona e consolidação 100% urbana. Os resultados mostraram que o escoamento superficial (Pe) na bacia do Itaim aumenta com a expansão da área de expansão urbana, bem como com a consolidação urbana. O uso de micro reservatórios reduz consideravelmente os volumes de escoamento. O micro reservatório com um volume de armazenamento de 3400 litros permitiu conter o fluxo promovido pelas chuvas de até 25 anos de retorno, simulando a expansão urbana de 50% sobre a área rural e os 6800 litros podem conter chuvas de até 200 anos. período de retorno para a mesma condição de simulação. Embora esse tipo de estrutura não tenha sido considerado na lei municipal de uso e ocupação do solo, este estudo demonstra que o uso de sistemas ou elementos hidráulicos com potencial para reduzir o escoamento pode ser um meio importante para garantir a sustentabilidade da urbanização. bacias hidrográficas com disposição planejada de águas pluviais.