The sensitivity of turbidity currents to mass and momentum exchanges between these underflows and their surroundings

Abstract

This study examines sensitivity of the layer‐averaged equations of motion for turbidity currents to changes in the parameters that describe how mass, momentum, and turbulent kinetic energy (TKE) are transferred between the flow and its surroundings in a channelized environment. This analysis shows that one‐dimensional flows traversing a constant slope are sensitive to small changes in the sediment and clear‐water entrainment parameters that describe mass transfer relationships. Uncertainties within these proposed relationships were quantified by applying a Bayesian sampler to available laboratory data. Sampled entrainment parameter values show a strong preference to values differing from those previously determined. The uncertainties within the entrainment relationships were then propagated into the dynamics of a reference flow (described by flow velocity, sediment flux, and height) to assess the degree to which uncertainty within the mass transfer functions affects predictions of flow behavior down‐slope. Given the range of sampled values, flow parameters were found difficult to predict beyond 200–500 meters. The entrainment relationships largely control the spatial and temporal patterns of erosion and deposition and thus the channel architectures. A wide range of entrainment parameters might be necessary to accurately predict the range of plausible flow dynamics and resulting channel morphologies.