Avaliação do impacto das mudanças climáticas na segurança de barragens: estudo de caso da barragem Banabuiú

Abstract

Dam safety aims to reduce the possibility of failures that could result in disasters, with consequences for the dam itself and the population downstream. In order to guarantee this safety, dam risk assessment includes the identification of potential critical events, including changes in the hydrological regime. This work aims to understand the impacts of climate change on critical flood events, allowing the risks associated with the dam to be identified and future scenarios to be considered. The study object was the Arrojado Lisboa Dam (Banabuiú), the main source of water for the Banabuiú Adductor System, an initiative developed by the Ceará State Government. Global Circulation Models (GCM) applied to hydrological modeling were used, with four CMIP6 climate models being applied: ACCESS-ESMI1-5, BCC_CSM2_MR, CanESM5 and MIROC-ES2L. The data was extracted and interpolated in order to generate projected IDF equations for the future, applying the Equidistant Quantile Matching Method for the SSP 2 4.5 and SSP 5 8.5 emissions scenarios. The rainfall results obtained from the climate models showed values close to those obtained from the observed data for the same region, as shown in the updated IDF curves. At the hydrological modeling stage in the climate change scenarios using HEC-HMS, it was observed for the 10.000 average recurrence interval (ARI) there are more exceptional flood scenarios resulting in the possible overtopping of the Arrojado Lisboa dam (Banabuiú) compared to the 1.000 average recurrence interval (ARI) scenario. The analysis of the probability of flood exceedance under climate change scenarios highlights that, despite the uncertainties presented by the GCMs, the probability of an extreme event being exceeded under climate change scenarios is considerable. It is therefore concluded that, given the critical scenarios obtained, it is essential to adopt strategies to guarantee dam safety in the climate change scenarios projected for the future, including reservoir operation plans.