Determinación de la rugosidad superficial y anchos de inundación en la planicie del río Salado (Santa Fe) para la crecida de 2003

Abstract

Floodplains in lowland rivers play a key role in the floods, as they store and conduct a major part of the flow, which derives the importance of proper representation of surface roughness in the hydrodynamic model. The study area corresponds to the stream of the Salado River (Santa Fe, Argentina) between the confluence with the Cululú creek and Provincial Route 70. The objective was to determine the surface roughness of the flood plain and wide for the extraordinary flood of 2003 with the computer system Hec-Ras. The Manning's roughness coefficient n was calculated with the Cowan equation for floodplains, emphasizing the determination of the factor that characterizes the influence of vegetation on the surface roughness (n4), since this component represents the main difference to the formula for channels. The simulation for non-stationary conditions, was calibrated with water levels at the time of peak action of the flood, wide flood and a satellite image radar. According to the simulation results, the floodplain carried more than 70% of peak flow. The widths calculated with variable spatial roughness, compared with other settings, confirming significant differences. These results demonstrate the relevance of the definition of surface roughness to estimate floodplain depths and flow distribution.