Gravity (or density currents) currents are a general class of flows (also known as stratified flows) in which flow takes place because of relatively small differences in density between two flows (Middleton, 1993). Gravity currents that are driven by gravity acting on dispersed sediment in the flow were called sediment gravity flows (Middleton & Hampton, 1973). Sediment gravity flows may occur in both subaerial (e.g. avalanches, pyroclastic flows and so on) and subaqueous ambients (e.g. bottom currents, turbidity currents, debris flow – see Simpson, 1997) and may flow above, below or inside the ambient fluid. The distinction regarding sediment gravity flows and open-channel flows is due to the order of magnitude of the density difference between the fluids. Sediment gravity flow are generally of the same order of magnitude, whilst open-channel flow the difference in density between the flow (e.g. rivers) and the ambient air is much higher than that. The interest in these types of flows are mainly due to four factors: (i) phenomenon comprehension highlighting the origin, transport and deposition processes; (ii) their great magnitude and unpredictability (potential environmental hazards); (iii) the lack of monitoring these events in nature and; (iv) because of their economic significance, since some deposits generated by such currents are prospective reserves of hydrocarbon. Despite the great progress addressing theoretical and analytical evaluation of these phenomena, particularly on the origin, transport and deposition of this class of flow, even today, they are not completely comprehended. Generally, the complexity of the phenomenon can be expressed by: (i) interaction between the flow and the bed morphology; (ii) the quantity and the composition of sediment transported and (iii) the complex mixing processes. As a consequence, the origin and the hydrodynamics properties of these flows are less understood than open-channel flows (Baas et al., 2004). Simple definitions, such as volumetric concentrations of sediments, its composition and size distribution of solid particles in the mixture as well as the sediment-support mechanisms are difficult to measure in nature which is also an indicative of such complexity. Kneller & Buckee (2000) commented that difficulties in understanding the dynamics of suspended sediment are extremely complex by virtue of turbulence. In that case, the phenomenon is: non-linear; non-uniform (variation in space) and unsteady (variation in time). If the flow contains large loads of sediments and/or cohesive sediments in suspension this complexity increases even more. Besides the variation of density with time and space (open boundary conditions), the mechanical properties (rheology) of the suspensions