 |
| Titel |
Spatial patterns of Transit-Time Distributions using δ¹⁸O-isotope tracer simulations at ungauged river locations |
| VerfasserIn |
Michael Stockinger, Heye Bogena, Andreas Lücke, Bernd Diekkrüger, Markus Weiler, Harry Vereecken |
| Konferenz |
EGU General Assembly 2013
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250075940
|
|
|
|
|
|
| Zusammenfassung |
| Knowledge of catchment response times to a precipitation forcing and of isotope tracer transit
times can be used to characterize a catchment’s hydrological behavior. The aim of this study
was to use one gauging station together with multiple δ18O-isotope monitoring locations
along the main stream to characterize the spatial heterogeneity of a catchment’s hydrological
behavior in the context of transit times. We present a method suitable for small catchments to
estimate the Transit-Time Distribution (TTD) of precipitation to any stream point using δ18O
tracer data, no matter if the stream point is gauged or ungauged. Hourly runoff and
precipitation data were used to determine the effective precipitation under base flow
conditions at Wüstebach (Eifel, Germany), a small, forested TERENO/TR32 test site.
Modeling was focused on base flow due to the weekly measurement intervals of δ18O. The
modeling period of 2.5 years was split up in six different hydrological seasons,
based on average soil water content, in order to ensure a good fit of the model.
Due to the small size of the Wüstebach catchment (27 ha) we assumed the derived
effective precipitation to be applicable for the whole catchment. For subsequent
modeling of stream water δ18O data we used effective precipitation as an input variable
and corrected in a two-step process for canopy evaporation and soil evaporation.
Thus we derived base flow TTDs for the ungauged stream and tributary locations.
Results show a different behavior of the catchment’s response time for different
catchment wetness conditions with respect to base flow formation. Winter seasons
show similar response times, as well as summer seasons, with the exception of one
summer with a considerable higher response time. The transit time of water across
the isotope observation points shows points more influenced by shallow source
waters than other points, where a higher contribution of groundwater is observable. |
|
|
|
|
|
|