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| Titel |
The role of electrical conductivity measurements to investigate streamflow generation in Alpine catchments |
| VerfasserIn |
Karina Cano-Paoli, Alberto Bellin, Gabriele Chiogna |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250121895
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| Publikation (Nr.) |
 EGU/EGU2016-782.pdf |
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| Zusammenfassung |
| The relationship between streamwater electrical conductivity (EC) and water discharge (Q)
has found wide applications in hydrology. In this work, we perform a systematic analysis of
the temporal correlation between these two signals at the gauging station of Vermiglio, in the
lower portion of the Vermigliana, an Alpine headwater stream in North-Eastern Italy. The
analysis is limited to the period June-November of 2012 and 2013. First, we analyze the
known hysteresis relating EC and Q, showing how rain-on-snow events occurring in early
autumn fall apart from this cycle. Then we perform wavelet analysis of the two signals
investigating the scales with the highest power spectrum. In addition, we investigate the
coherence between EC and Q wavelet spectra, showing that the two signals are strongly
correlated at a scale of 24 hours during the melting period and in particular when
glacier melting is significant, i.e. from July to August. The cross-correlation of
the two signals allows to identify a statistically significant time lag of 1-2 hours
between Q and EC during the melting period, while in early spring and autumn
the time lag is masked by the stronger influence of rainfall events. Moreover, the
analysis of the diurnal cycles of EC and Q evidenced clear patterns in the timing of
occurrence of minimum and maximum values during the melting season. In addition,
we show how the amplitude of the electrical conductivity signal can be used to
estimate the contribution to streamflow due to snow-melting in absence of rainfall
events. Overall, the analyses show that despite their correlation, EC and Q signals are
characteristic of different aspects of the hydrological response of the catchment
and support the hypothesis that they should be described using different transfer
functions.
Keywords: Electrical conductivity; Alpine catchment; streamflow generation; hysteresis;
wavelet analysis; cross-correlation; diurnal streamflow cycles. |
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