Eficiência dos dispositivos de baixo impacto de sistemas de drenagem urbana para eventos extremos de precipitação em uma bacia tropical

Abstract

There is growing concern that the risk of flooding will increase in many regions of the world, especially in metropolitan areas where there are large numbers of people and assets. As the frequency of extreme precipitation events will likely suffer interference induced by climate change, there is a need to review the design criteria for urban drainage systems, considering intense events and land occupation. To mitigate the effect of urbanization and ensure greater resilience of urban drainage, the proposition of a decentralized design of urban drainage infrastructure is used: low-impact urban devices (Low Impact Development, LID) that aim to achieve functional hydrological landscapes to control the peak and volume of flows in surface runoff. While the hydrological benefits of LIDs have been widely documented, the climate-related impacts of extreme precipitation events on device performance remain unknown. Thus, the objective of this work is to evaluate the efficiency of low-impact devices of urban drainage systems in a tropical basin in the face of extreme precipitation events caused by the effects of climate change. The study will consist of hydraulic modeling of a drainage basin with the insertion of devices at the lot level, such as: green roofs, rain barrels, permeable pavements and infiltration trenches. The efficiency was evaluated, in comparative terms of the devices, regarding the capacity to reduce the total volume and the maximum peak of the generated flow for three precipitation events and four different scenarios of implementation in the basin. The results showed that it should be evaluated that the ratio between the total area of the basin and the area of the LIDs influence the hydrological efficiency. Therefore, measures characterized as superficial, such as green roofs and permeable pavements, have relevant efficiency when implemented at higher coverage rates. If such a situation is unfeasible, a better alternative may be the adoption of elements whose efficiency is related to volumetric aspects, such as rain barrels and infiltration trenches. Furthermore, a single element typology with a larger area of coverage is more efficient when compared to the joint implementation of several devices for the same area of analysis.