Exploring controls on debris-flow surge velocity and peak discharge at Chalk Cliffs, Colorado, USA

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Abstract

We present a series of debris-flow events and use combined sensor and video data to explore how sediment concentration and triggering rainfall intensity affect the velocity and discharge of debris-flow surges generated by surface-water runoff. We analyze an initial data set of 49 surges from four debris-flow events recorded by a monitoring system at Chalk Cliffs, Colorado and compare measurements of surge height, velocity, peak discharge, triggering rainfall intensity, and qualitative estimates of sediment concentration. Measurements of sediment concentration and velocity were obtained using an automated camera system with a high resolution and frame rate. We find that the triggering rainfall intensity of the debris flows, which affects the sediment-to-water ratio, is a strong control on surge velocity and peak discharge. While surges with high and low sediment concentrations both exceed the peak discharge of water-only flow, fluid-rich surges generated by high rainfall intensities have much greater velocities and peak discharges than sediment-rich surges generated by lower rainfall intensities. These observations suggest that rainfall intensity may be an important predictive variable in empirical relationships for estimating the velocity and peak discharge of runoff generated debris flows, which are common in alpine areas and burned steeplands.

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Additional publication details

Publication type Conference Paper
Publication Subtype Conference Paper
Title Exploring controls on debris-flow surge velocity and peak discharge at Chalk Cliffs, Colorado, USA
Year Published 2019
Language English
Publisher Association of Environmental and Engineering Geologists
Contributing office(s) Geologic Hazards Science Center
Description 8 p.
Larger Work Type Book
Larger Work Subtype Conference publication
Larger Work Title Debris-flow hazards mitigation : mechanics, monitoring, modeling, and assessment ; proceedings of the Seventh International Conference on Debris-Flow Hazards Mitigation, Golden, Colorado, USA, June 10-13, 2019
First page 199
Last page 206
Conference Title Seventh International Conference on Debris-Flow Hazards Mitigation
Conference Location Golden, Colorado, USA
Conference Date June 10-13, 2019
Country United States
State Colorado
Other Geospatial Chalk Cliffs