Numerical modeling for the urban drainage gallery systems design

Abstract

Considering the frequent flooding of urban centers, the financial limitations and the inefficient management of Urban Drainage (UD) systems in Brazilian municipalities, it is necessary that projects be developed efficiently. These objectives are achieved with the correct definition of the diameter and galleries slope, resulting in adequate hydraulic ratios. It is also necessary to guarantee the flow without backwater, by verifying the energy grade line along the network. There are software capable of assisting the calculation, which, however, do not report optimized solutions. A vector-based numerical modeling is presented for the optimized sizing of a UD gallery system. This model was applied in an area and its results were compared with those obtained by two software in the Brazilian market. It is demonstrated the optimization developed contributes to increases the efficiency in the design. The main scientific contributions are: to characterize and model the typical design slopes, to obtain the optimum slope combined with the smaller diameter; to explore the potential of the hydraulic ratios above those normally employed, with positive effects on the definition of {D, ig} and the economy in the system; and to implement a recursive solution from a cycle of interdependent information, ensuring accuracy of results.

Sensitivity analysis of rainfall–runoff parameters models to estimate flows

“…Notably, certain precautions must be taken in estimating runoff with the use of recurrence periods in the referred rain-flow model. The critical rains from the micro-drainage project are chosen based on economic criteria, with the usual 5-10-year and probable flood not bringing significant losses (Bohnenberger et al 2019). For projects in urban areas or economic importance, Ward et al (2013) indicate that the longer the return period, the lower the probability that a flood event will occur.…”

“…This scenario triggers misinterpretations as the probability of the precipitations that overcome a catastrophic event of 100 years. Bohnenberger et al (2019) indicate that residential, commercial, public services, airports, and high-traffic arteries are dimensioned with the return period of 2-5-10years, while De Almeida et al (2016 recommends macro-drainage, commercial areas, residential and of specific importance vary between 50, 100 and 500 years.…”