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| Titel |
Groundwater dynamics under water-saving irrigation and implications for sustainable water management in an oasis: Tarim River basin of western China |
| VerfasserIn |
Z. Zhang, H. Hu, F. Tian, X. Yao, M. Sivapalan  |
| 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. 10 ; Nr. 18, no. 10 (2014-10-07), S.3951-3967 |
| Datensatznummer |
250120490
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| Publikation (Nr.) |
 copernicus.org/hess-18-3951-2014.pdf |
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| Zusammenfassung |
| Water is essential for life. Specifically in the oases of inland arid
basins, water is a critically limited resource, essential for the
development of the socio-economy and the sustainability of eco-environmental
systems. Due to the unique hydrological regime present in arid oases, a
moderate groundwater table is the goal of sustainable water management. A
shallow water table induces serious secondary salinization and collapse of
agriculture, while a deep water table causes deterioration of natural
vegetation. From the hydrological perspective, the exchange flux between the
unsaturated vadose zone and groundwater reservoir is a critical link to
understanding regional water table dynamics. This flux is substantially
influenced by anthropogenic activities. In the Tarim River basin of western
China, where agriculture consumes over 90% of available water resources,
the exchange flux between the unsaturated vadose zone and groundwater
reservoir is influenced strongly by irrigation. Recently, mulched drip
irrigation, a sophisticated water-saving irrigation method, was widely
applied in the Tarim River basin, which greatly impacted the exchange flux
and thus the regional groundwater dynamics. Capitalizing on recent progress
in evaporation measurement techniques, we can now close the water balance
and directly quantify the exchange flux at the field scale, thus gaining a
better understanding of regional groundwater dynamics. In this study,
comprehensive observations of water balance components in an irrigated
cropland were implemented in 2012 and 2013 in a typical oasis within the Tarim
River basin. The water balance analysis showed that the exchange flux and
groundwater dynamics were significantly altered by the application of
water-saving irrigation. The exchange flux at the groundwater table is
mostly downward (310.5 mm year−1), especially during drip irrigation
period and spring flush period, while the upward flux is trivial
(16.1 mm year−1) due to the moderate groundwater table depth (annual average
depth 2.9 m). Traditional secondary salinization caused by intense phreatic
evaporation (fed by upward exchange flux) is alleviated. However, a new form
of secondary salinization may be introduced unwittingly if there is lack of
water for periodic flushing, especially when brackish water is used in the
irrigation. Furthermore, the water saved via drip irrigation has been used
in further growth of irrigated lands instead of supporting the ecological
system. This could lead to an increased risk of eco-environmental degradation
and calls for improved governance schemes. The insights gained from this
study can be potentially applied to other arid inland areas (e.g., central
Asia) which face similar water shortages and human development problems. |
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