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| Titel |
Subsurface lateral flow from hillslope and its contribution to nitrate loading in streams through an agricultural catchment during subtropical rainstorm events |
| VerfasserIn |
B. Zhang, J. L. Tang, Ch. Gao, H. Zepp |
| 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 ; 15, no. 10 ; Nr. 15, no. 10 (2011-10-18), S.3153-3170 |
| Datensatznummer |
250012993
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| Publikation (Nr.) |
 copernicus.org/hess-15-3153-2011.pdf |
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| Zusammenfassung |
| Subsurface lateral flow from agricultural hillslopes is often overlooked
compared with overland flow and tile drain flow, partly due to the
difficulties in monitoring and quantifying. The objectives of this study
were to examine how subsurface lateral flow generated through soil pedons
from cropped hillslopes and to quantify its contribution to nitrate loading
in the streams through an agricultural catchment in the subtropical region
of China. Profiles of soil water potential along hillslopes and stream
hydro-chemographs in a trenched stream below a cropped hillslope and at the
catchment outlet were simultaneously recorded during two rainstorm events.
The dynamics of soil water potential showed positive matrix soil water
potential over impermeable soil layer at 0.6 to 1.50 m depths during and
after the storms, indicating soil water saturation and drainage processes
along the hillslopes irrespective of land uses. The hydro-chemographs in the
streams, one trenched below a cropped hillslope and one at the catchment
outlet, showed that the concentrations of particulate nitrogen and
phosphorus corresponded well to stream flow during the storm, while the
nitrate concentration increased on the recession limbs of the hydrographs
after the end of the storm. All the synchronous data revealed that nitrate
was delivered from the cropped hillslope through subsurface lateral flow to
the streams during and after the end of the rainstorms. A chemical mixing
model based on electricity conductivity (EC) and H+ concentration was
successfully established, particularly for the trenched stream. The results
showed that the subsurface lateral flow accounted for 29% to 45% of
total stream flow in the trenched stream, responsible for 86% of total
NO3−-N loss (or 26% of total N loss), and for 5.7% to
7.3% of total stream flow at the catchment outlet, responsible for about
69% of total NO3−-N loss (or 28% of total N loss). The
results suggest that subsurface lateral flow through hydraulically
stratified soil pedons have to be paid more attention for controlling
non-point source surface water pollution from intensive agricultural
catchment particularly in the subtropical areas with great soil
infiltration. |
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