Debris flows are episodic gravitational currents of high density (∼2,000 kg/m 3 (Wang et al., 2018)), consisting of highly concentrated mixtures of water, mud and solid debris particles in varying proportions (Coussot & Meunier, 1996). Their flow behavior has been described as intermediate between floods and landslides (e.g., Iverson & Vallance, 2001). Within debris flows, the solid fraction typically ranges between 50% and 90% (Coussot & Meunier, 1996), with solid particle sizes varying from clay to meter-sized boulders (Pérez, 2001).Occurring on steep slopes of loose debris, debris flows are often initiated by water supply (Badoux et al., 2009), typically via intense rainfalls, natural or artificial dams collapses or rapid snowmelt (Dowling & Santi, 2014;