Modelagem da influência da drenagem das águas pluviais da bacia do riacho Maceió no macrossistema de esgotamento sanitário de Fortaleza, Ceará

Abstract

The effluent collection and transport system in Brazilian cities is of the absolute separator type, common in tropical countries, which consists of separate systems for sewage and rainwater. However, the entry of rainwater into the sewage system, even with the existence of a specific infrastructure, is still quite common and can impair the efficiency of the system. This entry is mainly due to infiltration or through clandestine connections of the drainage system. In view of this, the main objective of the work is to evaluate the effect of rainwater drainage in the trunk collector of the Parque Ecologico located in the municipality of Fortaleza. For this, the RTK parameters methodology was used to determine the Rainfall Derived Infiltration and Inflow (RDII) volume, which is the contribution that infiltrates the sewage system. These three parameters represent, respectively, the entry of rainwater into the sanitary sewage system in relation to rainfall, the rise time and the ratio of the rise time to the decline time of the unit hydrograph. For this simulation, rainy events with maximum precipitation were applied from an intensity-duration-frequency curve (IDF), created by the PCSWMM software based on the series of data from the Pici station. Five scenarios of water inflow into the system were simulated for return periods equal to 2, 5 and 10 years. The results of this research allowed us to determine the nodes that overflowed in the different scenarios, with a total of eight nodes in the most critical scenario. The application of a method to evaluate the entry of rainwater into the sanitary sewage system is necessary to identify the points of greatest occurrence of problems related to overflow.