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| Titel |
Hillslope characteristics as controls of subsurface flow variability |
| VerfasserIn |
S. Bachmair, M. Weiler |
| 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 ; 16, no. 10 ; Nr. 16, no. 10 (2012-10-19), S.3699-3715 |
| Datensatznummer |
250013523
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| Publikation (Nr.) |
 copernicus.org/hess-16-3699-2012.pdf |
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| Zusammenfassung |
| Hillslope hydrological dynamics, particularly subsurface flow (SSF), are
highly variable and complex. A profound understanding of factors controlling
this variability is needed. Therefore we investigated the relationship
between variability of shallow water table dynamics and various hillslope
characteristics. We ask whether measurable hillslope properties explain
patterns of subsurface flow variability. To approach this question, shallow
water table dynamics of three adjacent large-scale hillslopes were monitored
with high spatial and temporal resolution over 18 months. The hillslopes are
similar in terms of topography and parent material, but different in
vegetation cover (grassland, coniferous forest, and mixed forest). We expect
vegetation to be an important driver of water table dynamics at our study
site, especially given the minor differences in topography. Various
hillslope properties were determined in the field and via GIS analysis:
common topography descriptors, well depth, soil properties via slug tests,
and several vegetation parameters. Response variables characterizing the
water table response per well were calculated for different temporal scales
(entire time series, seasonal scale, event scale). Partial correlation
analysis and a Random Forest machine learning approach were carried out to
assess the explainability of SSF variability by measurable hillslope
characteristics. We found a complex interplay of predictors, yet soil
properties and topography showed the highest single explanatory power.
Surprisingly, vegetation characteristics played a minor role. Solely
throughfall and canopy cover exerted a slightly stronger control, especially
in summer. Most importantly, the examined hillslope characteristics
explained only a small proportion of the observed SSF variability.
Consequently there must be additional important drivers not represented by
current measurement techniques of the hillslope configuration (e.g. bedrock
properties, preferential pathways). We also found interesting differences in
explainability of SSF variability among temporal scales and between both
forested hillslopes and the grassland hillslope. |
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