Characteristics of a finite secondary channel of the large Paraná river

LUCAS DOMINGUEZ RUBEN; RICARDO SZUPIANY; JORGE ABAD; CARLOS RAMONELL

Simposio; 9th Symposium River Coastal and Estuarine Morphodynamics; 2015

Finite secondary meandering (FSM) channels across the flood plain of the middle Parana river reach are found especially when the Parana anabranching river collapses with one of the valley edges, thus, the width and slope of the flood plain, and specific geomorphological units, allow a free evolution of these channels. Little or nothing is known about their formation, evolution and interaction with the Parana river main channel. The present study show preliminary results related to morphology, flow structure and evolution characteristics of a FSM located near Santa Fe city, Argentina (Colastiné river). Aerial photography and satellite images are used to describe the time evolution and geomorphic characterization. Flow structure and morphology is described from data obtained with acoustic instrument measurements. It seems that these channels originate at the outer bank of the bend along the Paraná river main channel, thus, there is a trap efficiency of water and sediments to maintain active this FSM. The geometric arrangements of this channel make it unique, with a straight initial segment and subsequently bends start to grow increasing its sinuosity and amplitude downstream. In agreement with this behavior, transverse bed slope and secondary flow intensities are higher in the downstream direction. These FSMs allow the study of meandering channels under formation and their relation to the main channel.