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Video‐based gravel transport measurements with a flume mounted light table
Author(s) -
Zimmermann André E.,
Church Michael,
Hassan Marwan A.
Publication year - 2008
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/esp.1675
Subject(s) - flume , bed load , sediment , sediment transport , geology , pixel , calibration , volume (thermodynamics) , hydrology (agriculture) , grain size , soil science , remote sensing , geotechnical engineering , geomorphology , computer science , mathematics , statistics , computer vision , geometry , physics , flow (mathematics) , quantum mechanics
The study of bedload transport processes is constrained by an inability to monitor the mass, volume and grain size distribution of sediment in transport at high temporal frequencies. Building upon a previously published design, we have integrated a high‐resolution (1392 × 1024 pixels) video camera with a light table to continuously capture images of 2–181 mm material exiting a flume. The images are continuously recorded at a rate of 15 to 20 frames per second and are post‐processed using LabView (™) software, yielding continuous grain‐size‐specific transport information on a per second basis. The video capture rate is sufficient to record multiple images of each grain leaving the flume so that particle velocities can be measured automatically. No manual image processing is required. After calibration the method is accurate and precise for sediment in the 2 mm through to 45 mm grain size classes compared with other means of measuring bedload. Based on a set of validation samples, no statistically significant difference existed between the D 10 , D 16 , D 25 , D 50 , D 75 , D 84 , D 90 and D 95 determined by sieving captured samples and the D i values determined with the system. On average the system overpredicted transport by 4 per cent ( n = 206, SD = 42%). This error can be corrected easily by simply weighing the mass of sediment that leaves the flume. The technology is relatively inexpensive and provides high‐resolution data on coarse sediment transport out of a flume. Copyright © 2008 John Wiley & Sons, Ltd.