Wind drives depositional pattern in a highly turbid river plume

FERNANDEZ, ROCIO; BONANSEA, MATIAS

San Jose

Conferencia; International Conference of Fluvial Hydraulics, River Flow 2012; 2012

By coupling in-situ and remotely sensed data with numerical modeling we evaluated plume dispersal patterns and rates and the forcing functions responsible for these transformations.Emphasis was placed on identifying transport processes that could be generalized across systems and discharge events. Above all, we identified the thresholds of wind stress and direction that may lead to the relatively large residence time of the post-fire nutrient enriched river plume in the surface mixed layer of a medium-sized reservoir. In this context, the momentum balance of the modeled plume showed that wind forces largely determined the subsequent path taken by the plume, and therefore, its depositional pattern into the reservoir. In particular, southward wind induced a strong plume dispersion that efficiently exported nutrient enriched sediments to the south of the waterbody. Along its pathway, deposition from the plume was calculated until most sediment had rained from the surface current. Effective settling velocities of the order 1mm/s explained then observed removal rates of suspended sediment from the turbid plume.