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| Titel |
Technical note on measuring run-off dynamics from pavements using a new device: the weighable tipping bucket |
| VerfasserIn |
T. Nehls, Y. Nam Rim, G. Wessolek |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 15, no. 5 ; Nr. 15, no. 5 (2011-05-06), S.1379-1386 |
| Datensatznummer |
250012775
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| Publikation (Nr.) |
 copernicus.org/hess-15-1379-2011.pdf |
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| Zusammenfassung |
Due to climate change, cities need to adapt to changing rainfall and
rainwater run-off dynamics. In order to develop an corresponding process
based run-off model for pavements, we had to improve the measurement
technique to detect run-off dynamics in an appropriate high resolution.
Traditional tipping buckets (TB) have a comparable low volume resolution,
capable to quantify the highest intensities in a range of expected flows.
This results in varying temporal resolutions for varying flow intensities,
especially in low resolutions for small flow events. Therefore, their
applicability for run-off measurements and other hydrological process studies
is limited, especially when the dynamics of both small and big flow events
shall be measured.
We improved a TB by coupling it to a balance and called it weighable tipping
bucket (WTB). This paper introduces the device set up and the according data
processing concept. The improved volume and temporal resolution of the WTB
are demonstrated. A systematic uncertainty of TB measurements compared to WTB
measurements is calculated. The impact of that increased resolution on our
understanding of run-off dynamics from paved urban soils are discussed,
exemplary for the run-off and the surface storage of a paved urban soil.
The study was conducted on a permeably paved lysimeter situated in Berlin,
Germany. Referring to the paved surface, the TB has a resolution of
0.1 mm, while the WTB has a resolution of 0.001 mm. The
temporal resolution of the WTB is 3 s, the TB detects individual
tippings with 0.4 s between them. Therefore, the data processing
concept combines both the benefits of the balance to measure small
intensities with that of the TB to measure high flow intensities.
During a five months period (July to November 2009) 154 rain events were
detected. Accordingly, the TB and WTB detected 47 and 121 run-off events. The
total run-off was 79.6 mm measured by the WTB which was 11 % higher
than detected by the TB. 95 % of that difference can be appointed to water,
which evaporated from the TB. To derive a surface storage estimation, we
analyzed the WTB and TB data for rain events without run-off. According to
WTB data, the surface storage of the permeable pavement is 1.7 mm,
while using TB data leads to an overestimation of 47 % due to low volume
resolution of the TB.
Combining traditional TB with modern, fast, high resolution digital balances
offers the opportunity to upgrade existing TB systems in order to improve
their volume detection limit and their temporal resolution, which is of great
advantage for the synchronization of water balance component measurements and
the investigation of hydrological processes. Furthermore, we are able to
quantify the uncertainty of flow measurements gained with traditional tipping
buckets. |
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