Author(s): Carlo Gualtieri, Marco Ianniruberto, Jim Best
Linked Author(s): Carlo Gualtieri
Keywords: Environmental hydraulics, river confluences, turbulent mixing, lateral stratification, upwelling/downwelling
Abstract: flow streamlines and potential mixing of separate flows. The fluid dynamics of confluences possess a highly complex structure with several common types of flow features. The confluence of the Negro and Solim�es Rivers, Brazil, ranks among the largest river junctions on Earth and its study may provide some general insights into large confluence dynamics and processes. An investigation has been recently conducted at this confluence at both low and high flow conditions. During this field research, a detailed series of acoustic Doppler velocity profiling (ADCP) transects, water quality samples and high-resolution seismic data are collected to investigate the key hydrodynamic and sediment transport features within this confluence. This paper firstly presents findings concerning the hydrodynamics and morphodynamics from these field studies. Second, the paper identifies and discusses the main processes controlling turbulent mixing at the Negro/Solim�es confluence, and more generally at confluences with large differences in velocity and water chemistry / sediment concentration between the merging rivers. These processes are: (1) a difference in velocity, i. e. shear, between the rivers, (2) a difference in density, i. e. lateral (and vertical) stratification, between the rivers, (3) bed friction, and (4) form roughness. Our analysis suggests that the dynamics of the mixing interface in this type of river confluence can be explained as a combination from these processes
Year: 2017