A comprehensive study of the river plume in a microtidal setting

On the basis of observations and modelling of the plume generated by the Misa River (AN, Italy), we performed acomprehensive study, which integrated different sources of information (field data, numerical simulations, etc.),of the generation and transport mechanisms of river plumes flowing into microtidal environments. First, weanalysed images simultaneously acquired by both two shore-based stations and satellite to determine plumefronts and extensions. Then, we correlated such information with the estuarine forcing to recognize the plumegeneration and transport mechanisms. Being real-life events influenced by a combination of factors, we runnumerical simulations to separately study each force and its influence on the plume evolution. We also performedsimulations of two real-life cases, to compare the modelled and observed results. We identified the riverdischarge and the wind as the main generation and transport mechanisms, respectively. Moreover, waves couldstir, suspend, and drag plume sediments, even if results showed that a river discharge associated with a returnperiod smaller than 1 year produced a plume denser than 5-year return period waves. The transport mechanismswere responsible for the alongshore extension of the plume. The tide, even if secondarily, affected the plumeevolution, depending on its phase shift to the river discharge peak. Particle Tracking Velocimetry from videosacquired by a shore-based station provided the surface velocity field in the final river stretch. This and thecontributions by wind and waves were correlated with the plume extension through a power law.