Essai de modélisation des flux solides dans l'Isère à Grenoble Relations avec l'hydroclimatologie

Solid discharge modelling for the Isère river near Grenoble Relations with hydroclimatology

EDF/DTG, Service Ressource en Eau et LTHE, Laboratoire des Transferts en Hydrologie et Environnement, Grenoble

Abstract

Suspended solids discharge (SSD) was measured for two years on the Isère river near Grenoble (France). The relations between SSD and water discharge are complex because of sediment storage in the river channel bed and banks. Rainfall and snowmelt runoff are statistically identified as the major factors contributing to sediment yield. Water level in the main tributary (Arc river) is the major factor contributing to sediment removal from the channel system and to downstream sediment transport.

A sediment storage model was tested on this river, in order to simulate SSD. It is based on erosivity of liquid precipitation and snowmelt on the one hand, and sediment store removal by the river flow on the other hand. The aims of the model are to extend short time series of suspended sediment concentrations with hydrological variables, to adapt suspended sediment sampling with real time predictions and to help in management of sedimentation in the downstream reservoir of St Egreve.

The conclusions of the study are that the model can simulate the SSD, that the snowmelt is the major process to take into account in SSD on the Isère river and that the performance of the model calibration is limited by anthropic activity (upstream reservoir release and hydraulic scouring of upstream reservoirs under flood conditions).