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| Titel |
Contrasts between estimates of baseflow help discern multiple sources of water contributing to rivers |
| VerfasserIn |
I. Cartwright, B. Gilfedder, H. Hofmann |
| 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. 1 ; Nr. 18, no. 1 (2014-01-03), S.15-30 |
| Datensatznummer |
250120242
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| Publikation (Nr.) |
 copernicus.org/hess-18-15-2014.pdf |
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| Zusammenfassung |
| This study compares baseflow estimates using chemical mass balance, local
minimum methods, and recursive digital filters in the upper reaches of the
Barwon River, southeast Australia. During the early stages of high-discharge
events, the chemical mass balance overestimates groundwater inflows,
probably due to flushing of saline water from wetlands and marshes, soils,
or the unsaturated zone. Overall, however, estimates of baseflow from the
local minimum and recursive digital filters are higher than those based on
chemical mass balance using Cl calculated from continuous electrical
conductivity measurements. Between 2001 and 2011, the baseflow contribution
to the upper Barwon River calculated using chemical mass balance is between
12 and 25% of the annual discharge with a net baseflow contribution of
16% of total discharge. Recursive digital filters predict higher baseflow
contributions of 19 to 52% of discharge annually with a net baseflow
contribution between 2001 and 2011 of 35% of total discharge. These
estimates are similar to those from the local minimum method (16 to 45%
of annual discharge and 26% of total discharge). These differences most
probably reflect how the different techniques characterise baseflow. The
local minimum and recursive digital filters probably aggregate much of the
water from delayed sources as baseflow. However, as many delayed transient
water stores (such as bank return flow, floodplain storage, or interflow)
are likely to be geochemically similar to surface runoff, chemical mass
balance calculations aggregate them with the surface runoff component. The
difference between the estimates is greatest following periods of high
discharge in winter, implying that these transient stores of water feed the
river for several weeks to months at that time. Cl vs. discharge variations
during individual flow events also demonstrate that inflows of high-salinity
older water occurs on the rising limbs of hydrographs followed by inflows of
low-salinity water from the transient stores as discharge falls. The joint
use of complementary techniques allows a better understanding of the
different components of water that contribute to river flow, which is
important for the management and protection of water resources. |
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