Hydrodynamic Modeling as a Tool for Water Risk Management in Rio Tapajos

The growing demands for the use of water have aggravated the quantity and quality of this vital resource and, together with extreme natural events, can intensify its degradation. Therefore, this study aims to analyze the extreme maximum flow events of a stretch of the Tapajos river, using the hydrodynamic model HEC-RAS. Four fluviometric stations and their respective historical series of elevation and flow were used, as well as the transversal profile of each station. The cross-sectional data were coupled with a Digital Elevation Model (MDE) originated from Shuttle Radar Topography Mission (SRTM) data. The flow rates were extrapolated to the 10, 25, 50 and 100 years Return Times (TRs), by means of the Generalized Extreme Value (GEV) frequency distribution, and the quotas were calculated using the hydrodynamic model. In the calibration step, the adjustment of the Manning roughness coefficient for the stations was made, which were from 0.041 to 0.095. The Nash-Stucliffe coefficient and R-2 were greater than 0.99 in all seasons. In the simulations, the dimensions varied between 111.04 and 20.15 m. The calibration and validation of the hydrodynamic model showed satisfactory adjustments between the simulated and observed data.