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| Titel |
Incipient subsurface heterogeneity and its effect on overland flow generation – insight from a modeling study of the first experiment at the Biosphere 2 Landscape Evolution Observatory |
| VerfasserIn |
G.-Y. Niu, D. Pasetto, C. Scudeler, C. Paniconi, M. Putti, P. A. Troch, S. B. DeLong, K. Dontsova, L. Pangle, D. D. Breshears, J. Chorover, T. E. Huxman, J. Pelletier, S. R. Saleska, X. Zeng |
| 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. 5 ; Nr. 18, no. 5 (2014-05-22), S.1873-1883 |
| Datensatznummer |
250120363
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| Publikation (Nr.) |
 copernicus.org/hess-18-1873-2014.pdf |
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| Zusammenfassung |
| Evolution of landscape heterogeneity is controlled by coupled Earth system
dynamics, and the resulting process complexity is a major hurdle to cross
towards a unified theory of catchment hydrology. The Biosphere 2 Landscape
Evolution Observatory (LEO), a 334.5 m2 artificial hillslope built with
homogeneous soil, may have evolved into heterogeneous soil during the first
experiment driven by an intense rainfall event. The experiment produced
predominantly seepage face water outflow, but also generated overland flow,
causing superficial erosion and the formation of a small channel. In this
paper, we explore the hypothesis of incipient heterogeneity development in
LEO and its effect on overland flow generation by comparing the modeling
results from a three-dimensional physically based hydrological model with
measurements of total mass change and seepage face flow. Our null hypothesis
is that the soil is hydraulically homogeneous, while the alternative
hypothesis is that LEO developed downstream heterogeneity from transport of
fine sediments driven by saturated subsurface flow. The heterogeneous case
is modeled by assigning saturated hydraulic conductivity at the LEO seepage
face (Ksat,sf) different from that of the rest (Ksat). A range of
values for Ksat, Ksat,sf, soil porosity, and pore size distribution
is used to account for uncertainties in estimating these parameters,
resulting in more than 20 000 simulations. It is found that the best runs
under the heterogeneous soil hypothesis produce smaller errors than those
under the null hypothesis, and that the heterogeneous runs yield a higher
probability of best model performance than the homogeneous runs. These
results support the alternative hypothesis of localized incipient
heterogeneity of the LEO soil, which facilitated generation of overland
flow. This modeling study of the first LEO experiment suggests an important
role of coupled water and sediment transport processes in the evolution of
subsurface heterogeneity and on overland flow generation, highlighting the
need of a coupled modeling system that integrates across disciplinary processes. |
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