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| Titel |
Nested investigation of subsurface connectivity between hillslopes and
streams |
| VerfasserIn |
Daniel Beiter, Theresa Blume, Markus Weiler |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250133272
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| Publikation (Nr.) |
 EGU/EGU2016-13862.pdf |
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| Zusammenfassung |
| The high spatial variability of the subsurface, and thereby the spatial variability of its
hydrological characteristics, still pose a great challenge to in-depth understanding and
prediction of subsurface flow and the mechanisms that dynamically connect hillslopes and
streams. Even though physical processes in porous media are theoretically very
well understood, predicting hillslopes’ responses to a specific (precipitation) event
can be very intricate, due to the structural heterogeneity of real hillslope-stream
systems.
In the here presented study (carried out as part of the Catchments As Organized Systems
(CAOS) research unit) we assess the linkage between hillslopes and streams via subsurface
flow paths. This linkage can also be called “Connectivity”, which describes separate regions
within a certain catchment as being in a linked state – or not – via water flux. We focus our
experimental efforts on several hillslopes with differing geological and morphological
properties and seek for indications of connectivity at the hillslope/stream reach
scale. These hillslopes are instrumented with soil moisture sensors and observation
wells measuring shallow groundwater levels, electric conductivity and temperature
continuously. This gives us a first indication of subsurface storage fluctuations and hillslope
responses. This setup is extended at selected sites by additional observation wells and
electrical resistivity tomography (ERT) transects which are measured in time lapse
mode. Hillslope scale forced flow through experiments, where subsurface water
flux is induced from upslope, will give an indication for a potential maximum of
connectivity in a more or less controlled, yet real, environment. First results of
these experiments are reported alongside with response patterns to natural rainfall
events.
The aim is to identify hydrological and morphological controls on subsurface
connectivity depending on the site’s characteristics, the system’s current state and the forcing
during an event. Possible threshold behaviour as well as different qualities of connectivity
(channelled vs. diffuse) should be detected and distinguished. |
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