Caracterização da qualidade da água pluvial retida em módulos experimentais de telhados verdes e o seu estudo como alternativa tecnológica para redução do volume da água pluvial escoada

Abstract

The alternative technology of green roofs has been used for many years by European and North American countries, but only in the last decade has gained market in Brazil. Among its benefits are the reduction of heat islands, the decrease of temperature variations, minimizing noise and air pollution. They can also increase urban biodiversity and make more aesthetically pleasing environment. Still can improve stormwater management and the quality of this water. Therefore, this study aimed to qualitatively characterize the rainwater captured experimental modules of green roofs, with three different types of vegetation located in the city of Cuiabá, MT. Also, evaluate the percentage of retention of rainwater captured by the same experimental modules of green roofs and analyze the intensity of rain influences the volume of retained rainwater. For that it was built three modules of green roofs testing three different vegetations were compared to a conventional roof. The water collected from the roofs were analyzed fifteen variables of water quality. So with regard to the quality of water abstracted by the experimental modules of green roofs has been observed that increased color characteristics and turbidity and acted as hubs of all analyzed nutrients. The concentrations of BOD, heterotrophic bacteria and fungi cultivated no differences between conventional roof and green roofs. In relation to total coliforms in green roofs results showed values of concentrations exceeding the conventional roof, however, the opposite occurred with respect to Escherichia coli. It was also noted that there is no longer adequate vegetation to improve the quality of the water, as are many factors that influence and that each vegetation operates differently. Green roofs can be used as minimizing problems related to urban drainage, since the results showed that green roofs can retain 46-61% water. Yet it was observed that the type of green roof vegetation has an effect on the flow retention amounts and green roofs of herbaceous and grassy showed the highest percentage of retention of rainwater drained by them. It was also observed that there is an inverse relationship between the intensity of precipitation and the percentage of rainwater is retained by green roofs, because the lower the intensity of the rain is higher retained volume of rainwater.