Modelagem do macrossistema de coleta de esgotos de Fortaleza-CE

Abstract

Field studies and computer simulations of the macro-sewer system in Fortaleza-CE, Brazil, integrating the SWMM to QGIS, were carried out in order to investigate the hydrological-hydraulic behavior of the Interceptor Leste (IL), under various operational conditions. The results showed that only in an ideal operating scenario, without interference from silting or rainwater infiltration, the IL would be able to support its flows. In a scenario with the presence of silted stretches, IL would start to work under a forced pipe condition in most stretches, presenting critical points of overflow. The occurrence of speeds below 1.0 m/s was identified as a possible cause for silting. However, simulations indicated that the removal of sediment barriers would be sufficient to eliminate overflows. Assessing the interference of rainwater infiltration in the IL, it was observed that it would be able to withstand rain intensities below 10 mm/h, provided that no more than 5% of the sub-basin area contributed to the interceptor. These simulations resulted in rainfall contributions of up to 80 L/(s.km), which is substantially higher than the value of 6 L/(s.km) recommended by the Brazilian Association of Technical Standards (ABNT). The combined impact of sediment deposition with rainwater infiltration was also investigated, resulting in an increase in overflows compared to previous scenarios. Finally, simulations considering various possibilities for removing sediment barriers showed that this measure alone would not be sufficient to eliminate overflows in the region.