Análisis de pendientes hidrométricas en grandes crecidas sobre tramo del río Paraná
Fecha
2010
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Centro Universitario Rosario de Investigaciones Hidroambientales (CURIHAM). Facultad de Ciencias Exactas, Ingeniería y Agrimensura. Universidad Nacional de Rosario.
Resumen
Descripción
En este trabajo se presenta un estudio sobre el comportamiento hidráulico de un tramo del sistema cauce-planicie aluvial del Río Paraná, desde Diamante hasta Ramallo, involucrando una longitud de 200 km aproximadamente. En el tramo se observa que el flujo encauzado en el curso principal, sobre margen dere-cha, es separado del escurrimiento en el valle de inundación mediante albardones naturales hasta aguas abajo de Rosario. El objetivo del trabajo es analizar el comportamiento del río en grandes crecidas a partir de regis-tros de niveles hidrométricos y caudales sobre el cauce principal. Los resultados son importantes para la realización de calibraciones de modelos aplicados en este tramo, y como antecedente para ríos con configura-ciones similares. Se calcularon pendientes longitudinales de la superficie libre por tramos y se contrastaron gráficas de pendientes-caudales-alturas. Cuando los caudales aumentan, manteniéndose menores a 25000 m³/s (flujo encauzado), se incrementan niveles hidrométricos y pendientes en todo el tramo. En cambio, al superar 25000 m³/s (anegamiento en el valle), el nivel hidrométrico en Rosario crece, pero más rápidamente se incrementa en San Nicolás por el retorno de flujo al cauce principal desde el valle, causando pendientes menores. Con caudales máximos, esta situación es más evidente. Se observa que en la interacción cauce-planicie el aumento del caudal no necesariamente implica un incremento de la pendiente hidráulica en el cauce, sino que depende de la configuración integral cauce-planicie y de la situación hídrica antecedente aguas abajo.
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 background 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 con-trast, 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 sur-face 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 discharge does not necessarily imply an increase in water surface slopes in the main channel, but depends on the inte-gral morphological configuration of channel-floodplain system and the state of the system downstream pre-vious to the incoming floods flows.
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 background 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 con-trast, 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 sur-face 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 discharge does not necessarily imply an increase in water surface slopes in the main channel, but depends on the inte-gral morphological configuration of channel-floodplain system and the state of the system downstream pre-vious to the incoming floods flows.
Palabras clave
Río Paraná, grandes ríos de llanura, registros en grandes crecidas