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| Titel |
Groundwater surface mapping informs sources of catchment baseflow |
| VerfasserIn |
J. F. Costelloe, T. J. Peterson, K. Halbert, A. W. Western, J. J. McDonnell |
| 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 ; 19, no. 4 ; Nr. 19, no. 4 (2015-04-07), S.1599-1613 |
| Datensatznummer |
250120673
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| Publikation (Nr.) |
 copernicus.org/hess-19-1599-2015.pdf |
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| Zusammenfassung |
| Groundwater discharge is a major contributor to stream baseflow. Quantifying
this flux is difficult, despite its considerable importance to water resource
management and evaluation of the effects of groundwater extraction on
streamflow. It is important to be able to differentiate between contributions
to streamflow from regional groundwater discharge (more susceptible to
groundwater extraction) compared to interflow processes (arguably less
susceptible to groundwater extraction). Here we explore the use of
groundwater surface mapping as an independent data set to constrain estimates
of groundwater discharge to streamflow using traditional digital filter and
tracer techniques. We developed groundwater surfaces from 88 monitoring bores
using Kriging with external drift and for a subset of 33 bores with shallow
screen depths. Baseflow estimates at the catchment outlet were made using the
Eckhardt digital filter approach and tracer data mixing analysis using major
ion signatures. Our groundwater mapping approach yielded two measures
(percentage area intersecting the land surface and monthly change in
saturated volume) that indicated that digital filter-derived baseflow
significantly exceeded probable groundwater discharge during most months.
Tracer analysis was not able to resolve contributions from ungauged tributary
flows (sourced from either shallow flow paths, i.e. interflow and perched
aquifer discharge, or regional groundwater discharge) and regional
groundwater. Groundwater mapping was able to identify ungauged sub-catchments
where regional groundwater discharge was too deep to contribute to tributary
flow and thus where shallow flow paths dominated the tributary flow. Our
results suggest that kriged groundwater surfaces provide a useful, empirical
and independent data set for investigating sources of fluxes contributing to
baseflow and identifying periods where baseflow analysis may overestimate
groundwater discharge to streamflow. |
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