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| Titel |
A groundwater recharge perspective on locating tree plantations within low-rainfall catchments to limit water resource losses |
| VerfasserIn |
J. F. Dean, J. A. Webb, G. E. Jacobsen, R. Chisari, P. E. Dresel |
| 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. 2 ; Nr. 19, no. 2 (2015-02-26), S.1107-1123 |
| Datensatznummer |
250120641
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| Publikation (Nr.) |
 copernicus.org/hess-19-1107-2015.pdf |
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| Zusammenfassung |
Despite the many studies that consider the impacts of plantation forestry on
groundwater recharge, and others that explore the spatial heterogeneity of
recharge in low-rainfall regions, there is little marriage of the two
subjects in forestry management guidelines and legislation. Here we carry
out an in-depth analysis of the impact of reforestation on groundwater
recharge in a low-rainfall (< 700 mm annually),
high-evapotranspiration paired catchment characterized by ephemeral streams.
Water table fluctuation (WTF) estimates of modern recharge indicate that
little groundwater recharge occurs along the topographic highs of the
catchments (average 18 mm yr−1); instead the steeper slopes in these areas
direct runoff downslope to the lowland areas, where most recharge occurs
(average 78 mm yr−1). Recharge estimates using the chloride mass balance (CMB)
method were corrected by replacing the rainfall input Cl− value with
that for streamflow, because most recharge occurs from infiltration of
runoff through the streambed and adjacent low gradient slopes. The
calculated CMB recharge values (average 10 mm yr−1) are lower than the WTF
recharge values (average 47 mm yr−1), because they are representative of
groundwater that was mostly recharged prior to European land clearance
(> BP 200 years). The tree plantation has caused a progressive
drawdown in groundwater levels due to tree water use; the decline is less in
the upland areas.
The results of this study show that spatial variations in recharge are
important considerations for locating tree plantations. To conserve water
resources for downstream users in low-rainfall, high-evapotranspiration
regions, tree planting should be avoided in the dominant zone of recharge,
i.e. the topographically low areas and along the drainage lines, and should
be concentrated on the upper slopes, although this may negatively impact the
economic viability of the plantation. |
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