Defining and characterizing wood-laden flows in rivers using home videos

¹ Institute for Environmental Sciences, University of Geneva, Geneva, Switzerland
² Instituto de Ciencias de la Tierra, Faculty of Science, Universidad Austral de Chile, Valdivia, Chile
³ Universidad Austral de Chile, RINA – Research Unit on Natural and Anthropogenic Risk, Valdivia, Chile
⁴ Department of Ecosystems and Environment, Pontificia Universidad Católica de Chile, Santiago, Chile
⁵ Hydraulic and Environmental Engineering Department, Pontificia Universidad Católica de Chile, Santiago, Chile
⁶ Marine Energy Research and Innovation Center (MERIC), Santiago, Chile
⁷ Department of Geosciences, Colorado State University, Fort Collins, CO 80523, USA
⁸ Laboratory of Forest Ecosystem Management, Department of Forest Science, Graduate School of Agriculture, Hokkaido University, Kita 9 Nishi 9, Kita-ku, Sapporo, Hokkaido 060-8589, Japan
⁹ Department of Earth Sciences, University of Geneva, Geneva, Switzerland

^* Corresponding author: virginia.ruiz@unige.ch

Abstract

Organic material (i.e., trees, branches, wood in general) is commonly neglected among the classical criteria to distinguish flow types, mostly due to the lack of direct observations of flows in which this load is significant. However, in forested basins, large amounts of wood can be transported. Here we define and characterize, for the first time, wood-laden flows and show that these flows may occur repeatedly in a river basin, carrying substantial amount of organic material, with probable impacts on the ecosystem and potential hazards. We propose a novel classification of flows from clear water to hypercongested wood debris flows, according to the composition of sediment, wood and water. Our results will contribute to a better understanding of flow phenomena in forested river basins, which may facilitate the design of better management strategies.