A New Two-Layer Model for the Flow and Morphodynamics of Long-Runout Turbidity Currents

Models of flow and morphodynamics of turbidity currents have been useful to describe such phenomena as self-acceleration, incipient channelization and the formation of subaqueous sediment waves. As yet, however, there is no model able to describe the morphodynamics of turbidity currents that can run out 100s or 1000s of km and create channels of similar length. Here we present a two-layer model that is easy to implement and can capture such features. The lower layer is driven by the presence of suspended sediment. The upper layer is essentially sediment-free water pulled along by the lower layer. The formulation alllows a quasi-normal solution for which the lower layer can reach a steady state with constant layer thickness and layer-averaged velocity, but the upper layer thickens indefinitely. Several applications of the model to turbidity currents in the deep sea and lakes are presented. The model can handle both Froude-supercritical and Froude-subcritical flow.