An unusually large debris flow at Hummingbird Creek, Mara Lake, British Columbia

Abstract

On 11 July 1997 a very large debris flow occurred at Hummingbird Creek, Mara Lake, British Columbia. Long-term antecedent precipitation was record breaking, whereas short-term precipitation at Salmon Arm did not exceed the 2 year return period for intensity. A 25 000 m3 debris avalanche was initiated downstream of a forest road culvert, which drained a small catchment that had been artificially increased by a factor of three. The debris avalanche entered the channel of Hummingbird Creek and triggered a debris flow. Velocities were back-calculated using the forced vortex equation and multiplied by the cross-sectional area to obtain peak discharge estimates that ranged from 600 to 1000 m3/s. Approximately 92 000 m3 of sediment was deposited during this event, which makes it the largest nonvolcanic debris flow recorded in British Columbia to date. A three-dimensional runout model was used to simulate this event. Results are in fair agreement with the observed behaviour. This study emphasizes the need to carefully manage forest resources with high downstream risks and the need for hazard assessments prior to development on alluvial fans.Key words: debris avalanche, debris flow, DAN model, hydroclimatic, peak discharge, British Columbia.

Recent debris flows in the Portainé catchment (Eastern Pyrenees, Spain): analysis of monitoring and field data focussing on the 2015 event

“…The value of µ is relatively high compared with values published in the literature (e.g. Rickenmann and Koch 1997;Jakob et al 2000;Hürlimann et al 2003), but is supported by the very coarse granulometry of the channel sediment. In contrast, the value of the turbulent friction term is at the lower end of the range regarding other published values.…”

Comparison of flow resistance relations for debris flows using a one-dimensional finite element simulation model

“…When comparing model simulation results with observations of natural debris flows, it is often possible to achieve a reasonable agreement between some of the predicted and observed characteristics (e.g. Jakob et al, 2000;Revellino et al, 2004;Rickenmann et al, 2006). Referring to Fig.…”

“…The Voellmy flow relation (Table 1, C) consists of a turbulent Chézy term, C, accounting for velocitydependent friction losses, and a Coulomb or basal friction term to describe the stopping mechanism, where the basal friction angle δ is typically only a fraction of the Coulomb angle φ (McDougall and Hungr, 2006). It has been successfully applied to debris flows (Rickenmann and Koch, 1997;Jakob et al, 2000;Hürlimann et al, 2003;Revellino et al, 2004) and other geophysical flows of granular material (Bartelt et al, 1999;Chen and Lee, 2003;Crosta et al, 2004). The combination of the Coulomb friction term or a yield stress term with a turbulent flow resistance relation (Table 1, D or E, respectively) can similarly be used.…”

Modeling debris-flow runout patterns on two alpine fans with different dynamic simulation models

“…Debrisflow parameters from our study are presented as yellow crosses and triangles, respectively. Debris-flow parameters from other studies (Scheidl et al, 2013;McDougall et al, 2006;Hungr et al, 2002;Hungr, 2008b;Bartelt et al, 2013b;Jakob et al, 2000), are given as brown squares. Rock avalanches are illustrated as green circles and ice-rock avalanches are denoted by blue diamonds (Pirulli et al, 2004;Evans, 1996, 2004;Hungr and McDougall, 2009;Hungr, 2008b;Evans et al, 2007;Allen et al, 2009;Sosio et al, 2008;Lipovsky et al, 2008;Schneider et al, 2010).…”