Experimental bed active-layer survey with active RFID scour chains: Example of two braided rivers (the Drac and the Vénéon) in the French Alps

Guillaume Brousse,Daniel Vazquez-Tarrio,Frédéric Liébault,Gilles Arnaud-Fassetta

doi:10.1051/e3sconf/20184004016

Abstract

An innovative scour chains device composed of active UHF RFID tags is proposed to survey the bed active layer. This device is tested on three cross-sections deployed along two large Alpine braided rivers: the Drac and the Vénéon. A specific field deployment procedure is developed, using a technique of drilling with a tube and a jack-hammer. After each flood, the device allows recording presence/absence of active tags inside a scour chain column. This provides the maximum scouring depth of the bed at the position of the column, and the topographic resurvey of the channel provides the net fill depth. Results show that bed active layer can reach up to 1.43 m during high flow conditions and remains <0.1 m during low and moderate flows. The main advantage of this technology against traditional scour chains is the rapidity and easiness with which the scouring depth is obtained after a flow event, notably under conditions of massive net deposition after the flow. This technology is therefore particularly suitable for large braided rivers, where traditional scour chains necessitate too much field efforts for their relocation, and can be rapidly lost under deep active layers.

Highlights

Traditional scour chains proposed by Leopold et al [1] are commonly used in river channels to constrain post-flood scour and fill depths [2,3]
This is an efficient device for measuring the bed active layer because scour chains are very cheap and they do not require the presence of an operator for measurement during flow events
This paper aims to describe and test a new experimental device for monitoring the bed active layer of mountain streams based on the use of a new generation of scour chains called “RFID

Summary

Introduction

Traditional scour chains proposed by Leopold et al [1] are commonly used in river channels to constrain post-flood scour and fill depths [2,3] This is an efficient device for measuring the bed active layer (db; vertical magnitude of the active channel; [4]) because scour chains are very cheap and they do not require the presence of an operator for measurement during flow events. Gendaszek et al [15] have proposed to use a chain composed by two

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