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| Titel |
The dynamics of cultivation and floods in arable lands of Central Argentina |
| VerfasserIn |
E. F. Viglizzo, E. G. Jobbágy, L. Carreño, F. C. Frank, R. Aragón, L. Oro, V. Salvador |
| 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 ; 13, no. 4 ; Nr. 13, no. 4 (2009-04-09), S.491-502 |
| Datensatznummer |
250011831
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| Publikation (Nr.) |
 copernicus.org/hess-13-491-2009.pdf |
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| Zusammenfassung |
| Although floods in watersheds have been associated with land-use change
since ancient times, the dynamics of flooding is still incompletely
understood. In this paper we explored the relations between rainfall,
groundwater level, and cultivation to explain the dynamics of floods in the
extremely flat and valuable arable lands of the Quinto river watershed, in
central Argentina. The analysis involved an area of 12.4 million hectare
during a 26-year period (1978–2003), which comprised two extensive flooding
episodes in 1983–1988 and 1996–2003. Supported by information from surveys
as well as field and remote sensing measurements, we explored the
correlation among precipitation, groundwater levels, flooded area and land
use. Flood extension was associated to the dynamics of groundwater level.
While no correlation with rainfall was recorded in lowlands, a significant
correlation (P<0.01) between groundwater and rainfall in highlands was
found when estimations comprise a time lag of one year. Correlations
between groundwater level and flood extension were positive in all cases,
but while highly significant relations (P<0.01) were found in highlands,
non significant relations (P>0.05) predominate in lowlands. Our analysis
supports the existence of a cyclic mechanism driven by the reciprocal
influence between cultivation and groundwater in highlands. This cycle would
involve the following stages: (a) cultivation boosts the elevation of
groundwater levels through decreased evapotranspiration; (b) as groundwater
level rises, floods spread causing a decline of land cultivation; (c)
flooding propitiates higher evapotranspiration favouring its own retraction;
(d) cultivation expands again following the retreat of floods. Thus,
cultivation would trigger a destabilizing feedback self affecting future
cultivation in the highlands. It is unlikely that such sequence can work in
lowlands. The results suggest that rather than responding directly and
solely to the same mechanism, floods in lowlands may be the combined result
of various factors like local rainfall, groundwater level fluctuations,
surface and subsurface lateral flow, and water-body interlinking. Although
the hypothetical mechanisms proposed here require additional understanding
efforts, they suggest a promising avenue of environmental management in
which cultivation could be steered in the region to smooth the undesirable
impacts of floods. |
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