Quantification of riverbank erosion and application in risk analysis

The estimation of river bank erosion requires the knowledge of both local hydrodynamic and erodibility characteristics. Models exist in literature that allow the estimation of the river bank shear stress, the fundamental parameter in evaluating the retreat given the discharge flow and the geometry of the river channel. In this study, two hydrodynamic models (1-D and 2-D) were combined with three shear stress models in order to obtain an estimation of the retreat on a study case on the river Cecina in Tuscany, Central Italy. A calibration of the models was performed based on observations from aerial photos of the region over a period of 10 years (1994–2004), and the results of the different combinations of the models are discussed and compared. A framework was developed for the risk analysis of land loss due to bank erosion based on the analyses of discharge flow time series and an excess shear stress erosion model. An application to the study case is provided by using the results of fluvial erosion modelling.