Small-scale study of Debris-Flows Interactions with a Lateral Debris Basin and Crossings: The Manival Torrent case study

¹ CNR, Centre d’Analyse Comportementale des Ouvrages Hydrauliques CACOH, 4, rue de Chalon sur Saône, 69007 Lyon, France
² INRAE, UR ETNA, Domaine Universitaire, 2 rue de la Papeterie, BP76, 38402 Saint-Martin-d’Hères Cedex, France
³ SYMBHI, Syndicat mixte des bassins hydrauliques de l’Isère, 9 Rue Jean Bocq, 38000 Grenoble, France
⁴ E.T.R.M., 581 Route de Mont Carmel, Chef-Lieu, 73700 Les Chapelles, France
⁵ Office National des Forêts - Direction Forêt & Risques Naturels, 9 quai Créqui, 38 000 Grenoble, France
⁶ Office National des Forêts - service de Restauration des Terrains en Montagne de l’Isère, 9 quai Créqui, 38 000 Grenoble, France

^* Corresponding author: dominique.laigle@inrae.fr

Abstract

Small-scale models are useful tools to study the interactions between debris flows and structures and channels. Small-scale modelling of debris flows remains however complicated because of the complex rheology and scaling challenges of these geophysical processes. An on-going study of a debris basin and the downstream channel where two fords and a bridge are located is presented in this extended abstract. The studied torrent is the Manival catchment, located near Grenoble in France. We present the catchment features, the scientific questions studied, some preliminary calibration results describing the mixtures used to model debris flows as well as results from three debris-flood and two debris-flow runs. In essence, the model highlighted that the structure enable a large share of the bedload transport to pass downstream. Debris flows can be more or equally trapped depending on their rheology which controls the surges dynamics and the deposition slope in the debris basin.