Comparison of measurement methods of the front velocity of small-scale debris flows

  • Francesco Bettella | francesco.bettella@unipd.it Department of Land, Environment, Agriculture and Forestry, University of Padova, Legnaro (PD), Italy.
  • Gian Battista Bischetti Department of Agricultural and Environmental Sciences - Production, Landscape, and Agroenergy, University of Milan, Italy.
  • Vincenzo D'Agostino Department of Land, Environment, Agriculture and Forestry, University of Padova, Legnaro (PD), Italy.
  • Simone Virginio Marai Department of Agricultural and Environmental Sciences - Production, Landscape, and Agroenergy, University of Milan, Italy.
  • Enrico Ferrari Department of Agricultural and Environmental Sciences - Production, Landscape, and Agroenergy, University of Milan, Italy.
  • Tamara Michelini Department of Land, Environment, Agriculture and Forestry, University of Padova, Legnaro (PD), Italy.

Abstract

Debris flow is a gravity-driven process, which is characterized by a travelling dense surge including large boulders, and it is followed by a more fluid tail. These characteristics make difficult the measurement of the mean flow velocity by means of common hydraulic techniques. Different methods can be used at real scale and small-scale to measure the front velocity but a dedicate comparison between available methods is still lacking. This research aims to compare the front velocity measurements in the transport zone of a miniature debris flow using three devices: i) a common digital video camera (29 frames per second); ii) a high speed thermo camera (60 fps); and iii) a laser photoelectric sensors system. The statistical analysis of data has highlighted no significant differences exist between front velocities obtained by means of the video camera and the thermo camera, whereas photocells data statistically differ from those achieved via the other systems. Some lack of data recorded by photocell was documented, while the thermo camera technique did not show significant loss of information being also helpful to detect the kinematic behaviour of single particles. Finally, the tests confirmed the influence of the solid volumetric concentration in the debris-flow mechanics, which promotes, ceteris paribus, the debris-flow slowing down.

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Published
2015-12-18
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Original Articles
Keywords:
Debris-flow velocity, flume experiments, laser photoelectric sensors, small-scale model, thermo camera.
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How to Cite
Bettella, F., Bischetti, G. B., D’Agostino, V., Marai, S. V., Ferrari, E., & Michelini, T. (2015). Comparison of measurement methods of the front velocity of small-scale debris flows. Journal of Agricultural Engineering, 46(4), 129-137. https://doi.org/10.4081/jae.2015.472

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