Data: 17/09/2014 à 19/09/2014
Local: São Paulo - Brazil
Evaluation of Alternatives for Reducing Flow Peaks in a Urban Watershed (PAP014915)
The lack of planning about the increasing urbanization processes, mainly regarding theirregular occupation of riverbanks and hillsides, the channelization and straightening of river beds and thesoil sealing has caused, among others environmental problems, the reduction in rainwater infiltration. Thereduction in the infiltration and the increment in the runoff fraction result in increased flows during rainyperiods, contributing to flood occurrence. These factors can be potentialized if the disorderly occupationoccurs in an urban watershed where critical morphometric parameters are observed, like high values ofcircularity ratio. This study aims to evaluate the efficiency of alternatives implementation that lead toamortization of flow peaks responsible for flooding thorough different scenarios based on simulation ofhydrological processes occurring in an urban watershed. Analyses were performed with the HydrologicalModeling System (HMS) software, developed by the Hydrologic Engineering Center (HEC) of US ArmyCorps of Engineers (USA) and the ArcGIS software, among others. As a case study, simulations weredone in a watershed with great historical problems of flooding events and which comprises the city ofUberaba, located in Minas Gerais State, Brazil. The simulations shown that the implementation ofindividual measurements, such as, channels cleaning, intervention in agricultural areas and theconstruction of reservoirs, if taken in isolation, have negligible changes in peak flows. The evaluation ofan already constructed reservoir that has a superficial area of 101,640 m² indicated an efficiency of 4% inpeak flow reduction. The set of measures to improve infiltration in urban area, through implementation ofgreen roofs, permeable pavements, percolation basins and reforestation, associated with reservoirconstruction in areas still available in the urban space, showed a satisfactory result, reducing theobserved peak flow in 18%, besides the delay in time of concentration. It can be concluded that, in thesecases, the combination of structural and non-structural measures should be prioritized in publicmanagement, as flood effects are related not only to natural resources degradation, but also, represent apublic health problem, having significant impacts in social, economic and environmental areas.