I END - Encontro Nacional de Desastres da ABRH

Data: 25/07/2018 à 27/07/2018
Local: Porto Alegre-RS
Mais informações: https://www.abrh.org.br/iend



Lucas Camargo da Silva Tassinari, Daniela Guzzon Sanagiotto, Hildo Stefani, Marcele Nonnenmacher Colferai


9 - Medidas estruturais e não estruturais para prevenção de desastres


Drainage systems consist of civil works employed to prevent and mitigate impacts caused by urban floods. Pumping stations are components of these systems used in places where there is a need to elevate water and they may present a significant impact on the costs associated with the system. Higher pumping stations design discharges result in big costs, while a system with undersized pumping will have to include reservoirs with a large capacity to damp the peak flow. Thus, this work aims to verify the economic effect of the design discharge, in order to contribute to the definition of hydrological guidelines used in projects of macrodrainage systems. The project flow is established by the hydrological risk, defined by the return period (RP), a criterion that usually varies from 10 to 100 years, according to brazilian agencies, for this type of structure. Determining the most optimized pumping design flow / reservoir volume configuration requires a technical-economic analysis, which considers scenarios with different flow rates and related costs. To this end, the project hydrographs were developed for the 10, 25 and 50 years of return period for an elevation with a contributing drainage area of 5 km², by using the SCS-CN method to estimate effective rainfall and the SCS Unit Hydrograph to turn effective precipitation into flow. In relation to the estimated costs of the system, unit costs were considered, based on budget data of an urban drainage system and reservoir project. Scenarios were simulated with flow rates for different return periods and pumping capacity equal to 50%, 75% and 100% of peak flow. Analysis of the results showed that it is more economically feasible to invest in water storage than in pumping capacity. Also, the results pointed out that the economic investments in systems designed for greater return periods may be 42% higher in comparison to the reference return period of 10 years. Finally, this study has shown that there is significant savings in projects when upstream reservoirs are used, but the availability of areas for construction of such structures in urban centers may limit such application.

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