Assessing different imaging velocimetry techniques to measure shallow runoff velocities during rain events using an urban drainage physical model
<p>Although surface velocities are key in the calibration of physically based urban drainage models, the shallow water depths developed during non-extreme precipitation and the potential risks during flood events limit the availability of this type of data in urban catchments. In this context,...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2021-02-01
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| Series: | Hydrology and Earth System Sciences |
| Online Access: | https://hess.copernicus.org/articles/25/885/2021/hess-25-885-2021.pdf |
| Summary: | <p>Although surface velocities are key in the calibration of
physically based urban drainage models, the shallow water depths developed
during non-extreme precipitation and the potential risks during flood
events limit the availability of this type of data in urban catchments. In
this context, imaging velocimetry techniques are being investigated as
suitable non-intrusive methods to estimate runoff velocities, when the
possible influence of rain has yet to be analyzed. This study carried out a
comparative assessment of different seeded and unseeded imaging velocimetry
techniques based on large-scale particle image velocimetry (LSPIV) and
bubble image velocimetry (BIV) through six realistic but
laboratory-controlled experiments, in which the runoff generated by three
different rain intensities was recorded. First, the use of
naturally generated bubbles and water shadows and glares as tracers allows
unseeded techniques to measure extremely shallow flows. However, these
techniques are more affected by raindrop impacts, which even lead to
erroneous velocities in the case of high rain intensities. At the same time,
better results were obtained for high intensities and in complex flows with
techniques that use artificial particles. Finally, the study highlights the
potential of these imaging techniques for measuring surface velocities in
real field applications as well as the importance of considering rain
properties to interpret and assess the results obtained. The robustness of
the techniques for real-life applications yet remains to be proven by means
of further studies in non-controlled environments.</p> |
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| ISSN: | 1027-5606 1607-7938 |