Modélisation du flux sédimentaire pendant une chasse hydraulique (Arc en Maurienne)

Abstract

Flushing events have a significant impact on the morphology and ecology of the downstream part of the river. A conceptual model is proposed to estimate the evolution of the suspended sediments load (SSL) along the Arc river during an annual flushing event. The main assumption of the model is the balance between deposition and erosion rates. Only three parameters need to be calibrated : the celerity of the sediment cloud peak, the mean diffusion rate along the river, and the initial SSL profile (represented by a simple function based on the maximum concentration and the width of the cloud). This model yields encouraging results for the prediction of the concentrations along the river. It has been calibrated on the 2006 flushing event and validated against data from the 2005 and 2007 events for the celerity and diffusion parameters. Some discrepancy appeared between the model and data for the maximum concentration. A comparison allows however to locate zones where deposition and erosion potentially occurred.