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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Extreme events, natural variability and climate change : Errors analysis in extreme rainfall recording due to tipping bucket rain gauge performance
Errors analysis in extreme rainfall recording due to tipping bucket rain gauge performance
The measurement of rain intensity is traditionally performed by means of tipping bucket rain gauges (TBRs), the most
popular and widespread type of rain gauge actually employed worldwide. These instruments are known to underestimate
rainfall at higher intensities (>100 mm/h) because of the rainwater amount that is lost during the tipping movement of the
buckets. The related biases are known as systematic mechanical errors and result in the overestimation of rainfall at
lower intensities (<50 mm/h) and underestimation at the higher rain rates. The TBR performance behavior may change
depending on bucket size and gauge model. Mechanical errors, although less important in terms of accumulated rainfall,
have a strong influence on the measurement of moderate to high rain intensities, with increasing impact as far as the
rain rate increases. On the other hand, intense rain-rates are usually characterized by a short duration, so that any
possible correction of the uncertainty connected with mechanical errors strongly depends on the available resolution in
time of the considered time series. These errors may produce significant effects over hydrological modeling when used
to simulate real events. This work looks for quantify the magnitude of TBR errors by testing several in service gauges,
with the real installation conditions, using a transportable rainfall simulator. Different rainfall intensities were simulated in
order to evaluate the gauge performance and its dependence on intensity. Results highlight high level of underestimation
in the gauges, which depend not only on the model and bucket size, but also on the maintenance conditions. The effect
over the rainfall measurement when considering extreme rainfall is very significant, with a high uncertainty level. Such
uncertainty should be taken into account for hydrological model calibration or extreme event simulations.
File Size : 208,728 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Extreme events, natural variability and climate change
Date Published : 28/08/2015
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