AVALIAÇÃO DE RESERVATÓRIOS DE DETENÇÃO COMO MEDIDA DE CONTROLE DO ESCOAMENTO SUPERFICIAL GERADO EM ÁREAS URBANAS

Abstract

The impermeability of the soil, intensified by the advance of the urbanization, increases the availability of surface runoff, aggravating the occurrence of urban floods. Taking that into consideration, the compensatory techniques are presented as an alternative to classical drainage, since they seek to neutralize the impacts of urbanization rather than just transfer them downstream. This work evaluated the effect of detention basins as a measure of control of runoff generated after the construction of a large horizontal residential condominium, using hydrological simulations performed in SWMM. The runoff generated in the condominium was simulated for three stages of urban development: pre urbanization, intermediate urbanization and post urbanization. In order to control the post-urbanization flow, the basins with control concentrated and distributed in subcatchments were simulated for graded levels of restriction of the maximum flow at the basin outflow: maximum pre-urbanization flow, 25% and 50% of the maximum flow after urbanization. Based on the observed behaviors, it was evaluated how the reservoirs contribute individually to the flow at the basin outflow. The results obtained showed that the post-urbanization maximum flow can be more than 20 times higher than the natural one. Moreover, although the detention basins have presented satisfactory efficiency in the control of the flow, both in concentrated and distributed forms, to reestablish the pre urbanization flow may be impracticable due to the dimensions and the overflow risk of the structures. Furthermore, the control of the maximum flow at the basin outflow resulted in the overlapping of the flow peaks of the reservoirs, reducing the delay of the flow peaks on the controlled hydrograph.