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| Titel |
True colors – experimental identification of hydrological processes at a hillslope prone to slide |
| VerfasserIn |
P. Schneider, S. Pool, L. Strouhal, J. Seibert |
| 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 ; 18, no. 2 ; Nr. 18, no. 2 (2014-02-28), S.875-892 |
| Datensatznummer |
250120296
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| Publikation (Nr.) |
 copernicus.org/hess-18-875-2014.pdf |
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| Zusammenfassung |
| This study investigated runoff formation processes of a pre-alpine hillslope
prone to slide. The experimental pasture plot (40 m × 60 m) is located in
the northern front range of the Swiss Alps on a 30° steep
hillslope (1180 m a.s.l., 1500 + mm annual precipitation). A gleysol (H-Go-Gr)
overlies weathered marlstone and conglomerate of subalpine molasse. We
conducted sprinkling experiments on a subplot (10 m × 10 m) with variable
rainfall intensities. During both experiments fluorescein line-tracer
injections into the topsoil, and sodium chloride (NaCl) injections into the
sprinkling water were used to monitor flow velocities in the soil. The
observed flow velocities for fluorescein in the soil were 1.2 and
1.4 × 10−3 m s−1. The NaCl breakthrough occurred almost
simultaneously in all monitored discharge levels (0.05, 0.25 and 1.0 m
depth), indicating a high-infiltration capacity and efficient drainage of
the soil. These initial observations suggested "transmissivity feedback", a form of subsurface
stormflow, as the dominant runoff process. However, the results of a
brilliant blue dye tracer experiment completely changed our perceptions of
the hillslope's hydrological processes. Excavation of the dye-stained soils
highlighted the dominance of "organic layer interflow", a form of shallow subsurface stormflow. The dye
stained the entire H horizon, vertical soil fractures, and macropores
(mostly worm burrows) up to 0.5 m depth. Lateral drainage in the subsoil or
at the soil–bedrock interface was not observed, and thus was limited to the
organic topsoil. In the context of shallow landslides, the subsoil (Go/Gr)
acted as an infiltration and exfiltration barrier, which produced
significant lateral saturated drainage in the topsoil (H) and possibly a confined
aquifer in the bedrock. |
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