Author(s): Mariateresa Franzoia; Michael Nones; Giampaolo Di Silvio
Keywords: No Keywords
Abstract: Starting from an equilibrium formulation of the sediment transport of rivers, we have developed a model that provides the instantaneous sediment transport of a river knowing a limited number of data. This is obtained assuming two principal processes: the production of the sediment input by surface-and mass-erosion from the watershed slopes and its transferring along the reach with a much larger delay with respect to the liquid wave (which is supposed here to propagate instantaneously). The approach consists in minimizing the deviations from a set of measured data using a model of the Ar Ma type. This work intends to rearrange a model initially developed for rivers with large watersheds, for this application to the smaller lowland watercourses flowing in the Lagoon of Venice. The available data come from some gauging stations recording hydrological and quality parameters of the river water in the period 2006-2011. In the case of small lowland watercourses with relatively uniform basin, the transported material is finer and the concentration of sediments does not have a large tempora variability as in the mountain basins. Sporadic exceptiona storms, however, can also produce substantial deviations from equilibrium. The original model structure appears to be reasonably applicable also to small arable-land watersheds. In this case, however, the sediment production can alternatively be expressed by a kind of rainfall factor in the U. S. L. E. formula.