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| Titel |
Processing and comparison of two weighing lysimeters at the Rietholzbach catchment |
| VerfasserIn |
Ruth Conall, Dominik Michel, Martin Hirschi, Sonia I. Seneviratne |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250144584
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| Publikation (Nr.) |
 EGU/EGU2017-8428.pdf |
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| Zusammenfassung |
| Weighing lysimeters are a well-established means of accurately obtaining local-scale
estimates of actual evapotranspiration and seepage within soils. Current state-of-the-art
devices have very high temporal resolutions and weighing precisions, and can also be used to
estimate precipitation. These, however, require complex filtering to first remove noise (e.g.
resulting from wind influence) from the mass measurements. At the Rietholzbach research
catchment in northeastern Switzerland, two weighing lysimeters are in operation. One is a
recently-installed state-of-the-art mini-lysimeter with a pump-controlled lower boundary; the
other is a large free-drainage lysimeter in operation since 1976. To determine the optimal
processing approach for the mini-lysimeter, a number of reported approaches were applied,
with the resulting evapotranspiration and precipitation records being compared to those of
the large lysimeter and a tipping bucket, respectively. Out of those examined, we
found the Adaptive-Window and Adaptive-Threshold (AWAT) filter and a similar,
non-adaptive approach, to perform best. Using the AWAT-filtered mini-lysimeter data as a
reference, additional, retrospectively-applicable processing steps for the large lysimeter
were then investigated. Those found to be most beneficial were the application of a
three-point (10-min) moving mean to the mass measurements, and the setting-to-zero
of estimated evapotranspiration and condensation in hours with greater-than-zero
reference tipping bucket precipitation recordings. A comparison of lysimeter mass
increases associated with precipitation revealed that the large lysimeter experiences a
previously unknown under-catch of 11.1% (for liquid precipitation). Daily seepage
measurements were found to be generally greater from the mini-lysimeter, probably
reflecting the reduced input of water to the large lysimeter due to this under-catch. |
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