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| Titel |
Advances in the Rising Bubble Technique for discharge measurement |
| VerfasserIn |
Koen Hilgersom, Willem Luxemburg, Geert Willemsen, Luuk Bussmann |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250089457
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| Publikation (Nr.) |
 EGU/EGU2014-3660.pdf |
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| Zusammenfassung |
| Already in the 19th century, d’Auria described a discharge measurement technique that
applies floats to find the depth-integrated velocity (d’Auria, 1882). The basis of this technique
was that the horizontal distance that the float travels on its way to the surface is the image of
the integrated velocity profile over depth. Viol and Semenov (1964) improved this method by
using air bubbles as floats, but still distances were measured manually until Sargent (1981)
introduced a technique that could derive the distances from two photographs simultaneously
taken from each side of the river bank. Recently, modern image processing techniques proved
to further improve the applicability of the method (Hilgersom and Luxemburg,
2012).
In the 2012 article, controlling and determining the rising velocity of an air bubble still
appeared a major challenge for the application of this method. Ever since, laboratory
experiments with different nozzle and tube sizes lead to advances in our self-made
equipment enabling us to produce individual air bubbles with a more constant rising
velocity.
Also, we introduced an underwater camera to on-site determine the rising velocity, which
is dependent on the water temperature and contamination, and therefore is site-specific.
Camera measurements of the rising velocity proved successful in a laboratory and field
setting, although some improvements to the setup are necessary to capture the air bubbles
also at depths where little daylight penetrates.
References
D’Auria, L.: Velocity of streams; A new method to determine correctly the mean
velocity of any perpendicular in rivers and canals, (The) American Engineers, 3,
1882.
Hilgersom, K.P. and Luxemburg, W.M.J.: Technical Note: How image processing
facilitates the rising bubble technique for discharge measurement, Hydrology and Earth
System Sciences, 16(2), 345-356, 2012.
Sargent, D.: Development of a viable method of stream flow measurement using the
integrating float technique, Proceedings of the Institution of Civil Engineers (London), Part 2,
71, 1-15, 1981.
Viol, V. and Semenov, V.: Experiments in measuring discharges in canals by the
photo-integration method, Soviet Hydrol. Selected Pap, 2, 198-199, 1964. |
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