Dr. Enrica Viparelli
Abstract
Recent studies on sediment transport, erosion and deposition have significantly advanced morphodynamic modeling of systems transporting mix-size sediments. However, problems in which movement of individual grains plays an important role, such as tracer transport and the emplacement of the internal fabric of alluvial deposits, remain challenging. A vertically continuous, morphodynamic approach is used here to derive an analytical solution describing the streamwise and vertical dispersal of tracers in an equilibrium bed composed of uniform sediment. In this model, properties of the alluvial deposit not only vary in the flow direction, they also continuously vary in the vertical direction, and this makes it suitable to study tracer stone fate and transport in a gravel bed river. The model was verified with laboratory experiments and a relation expressing the location of the maximum probability of entrainment as a function of the bed shear stress was derived. This relation was implemented for model validation at field scale on the Halfmoon Creek, Colorado USA, and on the Buech River, France. The validated model was then used to investigate how tracer dispersal varies with the amplitude of bed level fluctuations associated with sediment transport processes. This numerical exercise revealed that as the amplitude of the bed level fluctuations increases, the rate of tracer dispersal in the streamwise direction decreases more rapidly in time. In particular, when gaussian (normal) distributions are used to model the variability of bed levels around the mean and the probability of entrainment, as the standard deviation of bed level change increases, tracer streamwise dispersion transitions from super-diffusive to sub-diffusive.
Short bio
2003; MS in Environmental and Landscape Engineering, University of Naples Federico II, Italy.
2004 - 2007; Doctorate in Hydraulic, Transportation and Landscape Engineering, University of Naples Federico II, Italy. During the doctorate I was a visiting scholar at the Hydrosystems Laboratory, University of Illinois at Urbana-Champaign, where I worked with Prof. G. Parker and his group on experiments and numerical modeling of sediment sorting.
2008 - 2011; post-doctoral research associate at the Hydrosystems Laboratory, supervisor Prof. G. Parker.
2012 – 2017 assistant professor in the Department of Civil and Environmental Engineering, University of South Carolina at Columbia.
2018 – present associate professor in the Department of Civil and Environmental Engineering, University of South Carolina at Columbia
