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| Titel |
Conceptual and numerical modeling approach of the Guarani Aquifer System |
| VerfasserIn |
L. Rodriguez, L. Vives, A. Gómez |
| 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 ; 17, no. 1 ; Nr. 17, no. 1 (2013-01-25), S.295-314 |
| Datensatznummer |
250017691
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| Publikation (Nr.) |
 copernicus.org/hess-17-295-2013.pdf |
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| Zusammenfassung |
| In large aquifers, relevant for their considerable size, regional
groundwater modeling remains challenging given geologic complexity and data
scarcity in space and time. Yet, it may be conjectured that regional scale
groundwater flow models can help in understanding the flow system
functioning and the relative magnitude of water budget components, which are
important for aquifer management. The Guaraní Aquifer System is the
largest transboundary aquifer in South America. It contains an enormous
volume of water; however, it is not well known, being difficult to assess the
impact of exploitation currently used to supply over 25 million inhabitants.
This is a sensitive issue because the aquifer is shared by four countries.
Moreover, an integrated groundwater model, and therefore a global water
balance, were not available. In this work, a transient regional scale model
for the entire aquifer based upon five simplified, equally plausible
conceptual models represented by different hydraulic conductivity
parametrizations is used to analyze the flow system and water balance
components. Combining an increasing number of hydraulic conductivity zones
and an appropriate set of boundary conditions, the hypothesis of a
continuous sedimentary unit yielded errors within the calibration target in
a regional sense. The magnitude of the water budget terms resulted very
similar for all parametrizations. Recharge and stream/aquifer fluxes were
the dominant components representing, on average, 84.2% of total inflows
and 61.4% of total outflows, respectively. However, leakage was small
compared to stream discharges of main rivers. For instance, the simulated
average leakage for the Uruguay River was 8 m3 s−1 while the observed
absolute minimum discharge was 382 m3 s−1. Streams located in heavily
pumped regions switched from a gaining condition in early years to a losing
condition over time. Water is discharged through the aquifer boundaries,
except at the eastern boundary. On average, pumping represented 16.2% of
inflows while aquifer storage experienced a small overall increment. The
model water balance indicates that the current rate of groundwater
withdrawals does not exceed the rate of recharge in a regional sense. |
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