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

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 care...

[1]  Oldrich Hungr,et al.  Quantitative analysis of debris torrent hazards for design of remedial measures , 1984 .

[2]  Oldrich Hungr,et al.  A model for the runout analysis of rapid flow slides, debris flows, and avalanches , 1995 .

[3]  Ralph O. Kehle,et al.  Physical Processes in Geology , 1972 .

[4]  O. Hungr,et al.  Debris flow defenses in British Columbia , 1987 .

[5]  R. Hodgkins.  Controls on suspended-sediment transfer at a High-Arctic glacier, determined from statistical modelling , 1999 .

[6]  Comparison of Debris Flow Modelling Approaches , 1997 .

[7]  D. Varnes.  SLOPE MOVEMENT TYPES AND PROCESSES , 1978 .

[8]  Matthias Jakob,et al.  Morphometric and geotechnical controls of debris flow frequency and magnitude in Southwestern British Columbia , 1996 .

[9]  Matthias Jakob,et al.  Two Debris Flows with Anomalously High Magnitude , 1997 .

[10]  M. Jakob,et al.  The July 29, 1998, debris flow and landslide dam at Capricorn Creek, Mount Meager Volcanic Complex, southern Coast Mountains, British Columbia , 2000 .

[11]  R. P. Jordan.  Debris flows in the southern Coast Mountains, British Columbia : dynamic behaviour and physical properties , 1995 .

[12]  D. F. VanDine,et al.  Debris flows and debris torrents in the Southern Canadian Cordillera , 1985 .

[13]  M. Church,et al.  Meteorological antecedents to debris flow in southwestern British Columbia; Some case studies , 1987 .

[14]  Robert H. Webb,et al.  Debris flows from tributaries of the Colorado River, Grand Canyon National Park, Arizona , 1987 .

[15]  D. J. Vanes.  Slope movement types and processes, in Landslides Analysis and control , 1978 .

[16]  Helmut J. Körner,et al.  Reichweite und Geschwindigkeit von Bergstürzen und Fließschneelawinen , 1976 .

[17]  J. Clague,et al.  The Dusty Creek landslide on Mount Cayley, British Columbia , 1982 .

[18]  Matthias Jakob,et al.  The role of debris supply conditions in predicting debris flow activity , 1999 .

[19]  R. Iverson,et al.  U. S. Geological Survey , 1967, Radiocarbon.