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| Titel |
Relative impacts of key drivers on the response of the water table to a major alley farming experiment |
| VerfasserIn |
S. L. Noorduijn, K. R. J. Smettem, R. Vogwill, A. Ghadouani |
| 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. 11 ; Nr. 13, no. 11 (2009-11-05), S.2095-2104 |
| Datensatznummer |
250012050
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| Publikation (Nr.) |
 copernicus.org/hess-13-2095-2009.pdf |
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| Zusammenfassung |
Widespread clearing of native vegetation in Southwest Western Australia has
led to land degradation associated with rising groundwater, secondary
salinisation and waterlogging. Re-establishing deep-rooted perennial
vegetation across parts of the landscape is one technique for managing land
degradation. Alley farming is an agroforestry practice where multiple
perennial tree belts are planted in alternation with traditional
agricultural crops. To identify the best configuration (belt width versus
alley width) for controlling rising groundwater levels and providing viable
economic returns, a large scale experiment was established in 1995. The
experiment contains seven different alley farming designs, each with
transects of piezometers running across tree belts into adjacent alleys to
monitor changes in the groundwater level. Two control piezometers were also
installed in an adjacent paddock. Groundwater at the site is shallow (<3 m)
and of poor quality (pH 3–5, Ec 2.1–45.9 mS cm−1) so root water
uptake from the saturated zone is limited.
Simple hydrograph analysis could not separate treatment effects on the water
table response. Subsequent statistical analysis revealed that 20–30% of
the variability in the water table data over the 12 year study period was
attributable to the alley farming experiment. To futher investigate the
effect of the experiment on groundwater response, additional hydrograph
analysis was conducted to compare the trends in the control piezometers in
relation to those located within the belts. A difference of 0.9 m was
observed between the mean groundwater levels in the control piezometers and
the mean levels in the perennial belt piezometers. For a mean specific yield
of 0.03 m3 m−3 (standard deviation of 0.03 m3 m−3) this
equates to an additional average annual water use of 27 mm yr−1
(standard deviation of 33 mm yr−1) by the perennial agroforestry
system. It is concluded that declining annual rainfall is the principal
control on hydrograph response at the site, whilst perennial biomass
development has a lesser impact on water table depth. |
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