Author(s): Silvia Cilli; Paolo Billi; Leonardo Schippa; Edoardo Grottoli; Paolo Ciavola

Linked Author(s): Leonardo Schippa

Keywords: No Keywords

Abstract: The Fiumi Uniti and Savio rivers are two small sandy-bed river systems which sediment yield contributes feeds part of the EmiliaRomagna beaches (Italy). Since the twentieth century the northern Adriatic coast has been affected by well-known beach retreat phenomena. As the sediment supply of these local rivers is not well known, an analysis of bedload transport rates for the last 10 kilometres of the river has been done. Multiple analysis, supported by direct field measurements of the 2005-06and 2017 years (still ongoing) have been realized. Complementary hydraulic investigation and modelling have been performed. Repeated bedmaterial samplings have been carried out during different flood conditions, obtaining a significant number of observations. Aiming at defining the behaviour of sediment-transport in these two rivers, this paper focuses on the analysis of threshold sediment transport condition. Several formulae available in literature were used to test the field measurements. All these criteria seem inappropriate to predict the threshold conditions for bed particle entrainment in terms of the value of bed shear stress. The inaccurate estimation given by these formulae is due to the fact that they do not consider natural grain-shape factors or are mainly suitable for gravel-bed rivers.

DOI: https://doi.org/10.1051/e3sconf/20184004002

Year: 2018