Análisis de pendientes hidrométricas en grandes crecidas sobre tramo del río Paraná

Abstract

In this work a study on the hydraulic behavior of a river floodplain reach of the Paraná River, from Diamante to Ramallo is presented. The studied reach has a length of 200 Km approximately. In the reach it is observed that the stream flow channeled into the main course is separated from the runoff in the floodplain by natural levees up to downstream of Rosario. The study aims to analyze the hydraulic behavior of the river during large floods from water levels and discharge measurements performed in the main stream. The results are important for the calibration of mathematical models used in the reach, and as backgro und for rivers with similar configurations. Longitudinal water surface slopes were calculated and slope discharge water level relationships were analyzed. It is observed that when the discharge is increased, keeping less than 25000 m³/s (channeled flow), the water level and slopes are correspondingly augmented in the entire river reach. In contrast, exceeding 25000 m³/s (inundated floodplain), the water level in Rosario grows, but increases faster in San Nicolás due to the return of flow from the valley to the main channel, causing a lowering in water surface slopes between Rosario and San Nicolás. That behaviour is much more evident for maximum discharges during very large floods. It is observed that, in the channel floodplain interaction, increasing the di scharge does not necessarily imply an increase in water surface slopes in the main channel, but depends on the integral morphological configuration of channel floodplain system and the state of the system downstream previous to the incoming floods flows .