Impacto das mudanças climáticas no sistema de drenagem urbana da bacia do açude Santo Anastácio, em Fortaleza - Ceará

Abstract

Urban drainage systems are essential stormwater infrastructures for discharging surface runoff into water bodies. However, climate change can impact the efficiency of the system and cause disruptions. Therefore, this study investigates the hydrological-hydraulic modeling of the urban drainage system of the Santo Anastacio Reservoir (ASA) basin using the PCSWMM software for analysis of Intensity-Duration-Frequency (IDF) curves and its application in the prediction of extreme events in urban drainage systems. The IDF curves were generated for different climate change scenarios, including RCP 4.5 and RCP 8.5, using global circulation models. In addition, the hydrological responses of the IDF equation from the literature proposed for Fortaleza were compared with those of the software. The results indicate that the median in the RCP 8.5 scenario (approximately 210 mm) is lower than in the RCP 4.5 scenario (approximately 235 mm), and that models such as CESM1-CAM5-8.5 project more intense extreme events, while bcc-csm1-4.5 presents more conservative predictions. The hydraulic modeling revealed that the ASA sub-basin has a potential risk of socio-environmental impacts, given the uncertainties of climate change, and faces runoff problems due to the undersizing of the drainage system, resulting in flooding and overloading of conduits. Furthermore, it found similarity between the IDF equation from the literature proposed for Fortaleza and that of the software. The scenarios with greater rainfall intensity presented the highest runoff coefficients and flood volumes. The hyetogram analysis indicated that the symmetric distribution of 24- hour storms used by PCSWMM is effective in representing the simulated events. It is concluded that the adoption of future-adapted IDF curves is essential for improving urban drainage infrastructure and mitigating risks associated with extreme weather events.