The Orinoco River is the third largest flow-discharge river in the world with an average water flow of 37,600 m3s-1. Due to the presence of the Guyana shield on the right bank, the lower reach of the Orinoco presents a plan form characterized by alternance of contraction and expansion zones (Laraque et al., 2013). Typical 1-1.5 km width narrow reaches are followed by 7-8 km wide reaches (Figure 1). A complex pattern of bed aggradation and degradation processes takes place during the hydrological cycle. The relationship between
flow velocity and morphodynamic of sand waves and bars in an expansion/contraction channel is very important to understand the processes that control the evolution of rivers. Considerable research efforts has recently been directed towards the understanding of
fluvial processes associated with geomorphology and hydrologic conditions with the river width, which are explained through the mechanics of formation and evolution of sand waves and bars
