Use of Hydrologic and Hydraulic Models for Flood Management in Viana, Es, Brazil (PAP014899)

Código

PAP014899

Autores

Fillipe Tesch, Marco Aurelio Costa Caiado, Kleber Pereira Machado, Felippe Zuccolotto Pereira, Marcela Majesk, Marcela Lopes Barros, Tainah Christina Teixeira de Souza

Tema

Urban Floods

Resumo

The city of Viana, located in the metropolitan region of Vitoria, the capital of the Espirito Santo State, Brazil, has shown problems of urban drainage inherent to its fast urban growth, which deteriorates life quality due to the increasing frequency and level of urban floods. The Santo Agostinho Creek watershed encompasses the downtown area, some neighborhoods of high population, industrial areas and major highways that access the Metropolitan Region. This watershed has presented problems of flood very often and was studied. Water flows of the Santo Agostinho creek were appropriated using HEC-HMS (Hydrologic Engineering Center - Hydrologic Modeling System), which calculates flow from a watershed with known soil type and land use, using rainfall data. To calculate rainfall excess, it was selected the method of the SCS unit hydrograph. The intensity of rainfall for return period of 5, 10, 20, 25, 30, 50 and 100 years with duration equals to three times the time of concentration was calculated using the IDF equation, which was prepared using data from a raingage located inside the watershed. The flow rates were calculated for both current and future landuse and the future use of soil was simulated according to the city growth trends for the next 20 years. For the hydraulic simulation, it was used the mathematical model HEC-RAS 4.1 (River Analysis System), which was developed by the U.S. Army Hydrologic Engineering Center of the Corps of Engineers. The model is based on the solution of one-dimensional energy equation (Bernoulli), and evaluates energy losses by friction (Manning's equation) and by contraction or expansion of the cross sections. The HEC-RAS model is widely used for determining flood areas and for the simulation of hydraulic structures such as bridges, culverts and dams. The hydraulic simulations resulted in flooding areas with recurrence of 5, 10, 20, 25, 30, 50 and 100 years. The 100-year flood reached 363 ha, while the 5-year reached 158 ha. It was estimated that floods with recurrence of 5 years reaches directly 1,074 citizens, while floods of 25 years reaches 1,795 citizens. Structural solutions simulated for solving flood problems in the studied watershed encompass the construction of detention dams, galleries, bridges and dikes associated with pumping stations.