Banca de DEFESA: BYATRIZ CORDEIRO LÉDO

Analysis of the Hypothetical Failure of the CAER Dam in the municipality of Alto Alegre/RR

Dam rupture, flood map, HEC-RAS.

This study aims to simulate the hypothetical failure of the CAER SNISB 5291 dam due to "piping" and to evaluate the impacts on the areas downstream of the dam using a flood map. Specific objectives include inspecting the dam located in the municipality of Alto Alegre-RR, analyzing the dissipation of the flood wave generated by the dam’s failure using a hydrological model, and providing insights for the management and regulation of water resources through the generated maps. The CAER SNISB 5291 dam was chosen for this study due to the lack of periodic analyses by the owner and the state regulatory agency, its proximity to the urban area, and the presence of road infrastructure on its crest, which poses a significant risk to human lives and to the social and economic activities of the municipality. The study of the watershed upstream of the dam allowed for the determination of the inflow hydrograph and the calculation of the region's average annual precipitation. Using RAS Mapper, a tool from the HEC-RAS software, the main channel and the dam structure were defined to simulate the failure in a nonpermanent regime. A total of 132 cross-sections were created along the main channel, spaced 30 meters apart. The methodology of MacDonald & Langridge-Monopolis (1984) was applied to determine the breach parameters, resulting in a breach formation time of 0.21 hours. The HEC-RAS simulation revealed that the flood extent downstream spreads over agricultural areas and that a significant portion of the water does not flow superficially, showing uniform velocity along the channel. The flood map created indicated that the dam's failure would have substantial impacts on the population around the city of Alto Alegre-RR.