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Article: One-dimensional airflow in unsaturated zone induced by periodic water table fluctuation

TitleOne-dimensional airflow in unsaturated zone induced by periodic water table fluctuation
Authors
Issue Date2005
PublisherAmerican Geophysical Union.
Citation
Water Resources Research, 2005, v. 41 n. 4, p. 1-10 How to Cite?
AbstractThis paper investigates the vertical airflow driven by fluctuating water table within the lower layer of a coastal two-layered system. The upper layer is unsaturated and semipermeable, while the lower is permeable. An analytical solution of the subsurface air pressure fluctuation is derived on the basis of model simplification assumptions, the reasonability of which was examined by numerical solutions of the original nonlinear model. The airflow in the upper layer is controlled from the top by the constant atmospheric pressure and from the bottom by a temporally fluctuating air pressure P0(t), which is spatially constant in the unsaturated zone of the lower layer. For a sinusoidal head the amplitude of P0(t) increases with the frequency of the head fluctuation, the upper layer's thickness, and the unconfined aquifer's air-filled porosity and decreases with the upper layer's permeability. The phase shift of P0(t) ranges from 0 to π/2, indicating a "time advance." Particularly, P0(t) is approximately proportional to the temporal derivative of the head for sufficiently thin or permeable upper layer and to the head itself for sufficiently thick or less permeable one. The fluctuation amplitude of the water table is always less than that of the head and can be only one tenth of the latter if the upper layer is sufficiently thick or less permeable, which may slow significantly the landward attenuation speed of the tide-induced head fluctuation in a coastal "air-confined" aquifer. The analytical solution was used to estimate the value range of the air permeability of the marine sand fill at a coastal reclamation area of Hong Kong. Copyright 2005 by the American Geophysical Union.
Persistent Identifierhttp://hdl.handle.net/10722/72938
ISSN
2015 Impact Factor: 3.792
2015 SCImago Journal Rankings: 2.661
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorLi, Hen_HK
dc.contributor.authorJiao, JJen_HK
dc.date.accessioned2010-09-06T06:46:31Z-
dc.date.available2010-09-06T06:46:31Z-
dc.date.issued2005en_HK
dc.identifier.citationWater Resources Research, 2005, v. 41 n. 4, p. 1-10en_HK
dc.identifier.issn0043-1397en_HK
dc.identifier.urihttp://hdl.handle.net/10722/72938-
dc.description.abstractThis paper investigates the vertical airflow driven by fluctuating water table within the lower layer of a coastal two-layered system. The upper layer is unsaturated and semipermeable, while the lower is permeable. An analytical solution of the subsurface air pressure fluctuation is derived on the basis of model simplification assumptions, the reasonability of which was examined by numerical solutions of the original nonlinear model. The airflow in the upper layer is controlled from the top by the constant atmospheric pressure and from the bottom by a temporally fluctuating air pressure P0(t), which is spatially constant in the unsaturated zone of the lower layer. For a sinusoidal head the amplitude of P0(t) increases with the frequency of the head fluctuation, the upper layer's thickness, and the unconfined aquifer's air-filled porosity and decreases with the upper layer's permeability. The phase shift of P0(t) ranges from 0 to π/2, indicating a "time advance." Particularly, P0(t) is approximately proportional to the temporal derivative of the head for sufficiently thin or permeable upper layer and to the head itself for sufficiently thick or less permeable one. The fluctuation amplitude of the water table is always less than that of the head and can be only one tenth of the latter if the upper layer is sufficiently thick or less permeable, which may slow significantly the landward attenuation speed of the tide-induced head fluctuation in a coastal "air-confined" aquifer. The analytical solution was used to estimate the value range of the air permeability of the marine sand fill at a coastal reclamation area of Hong Kong. Copyright 2005 by the American Geophysical Union.en_HK
dc.languageengen_HK
dc.publisherAmerican Geophysical Union.en_HK
dc.relation.ispartofWater Resources Researchen_HK
dc.rightsWater Resources Research. Copyright © American Geophysical Union.en_HK
dc.titleOne-dimensional airflow in unsaturated zone induced by periodic water table fluctuationen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0043-1397&volume= 41 No 4 W04007&spage=&epage=&date=2005&atitle=One-dimensional+airflow+in+unsaturated+zone+induced+by+periodic+water+table+fluctuationen_HK
dc.identifier.emailJiao, JJ:jjiao@hku.hken_HK
dc.identifier.authorityJiao, JJ=rp00712en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1029/2004WR003916en_HK
dc.identifier.scopuseid_2-s2.0-19044387429en_HK
dc.identifier.hkuros108565en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-19044387429&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume41en_HK
dc.identifier.issue4en_HK
dc.identifier.spage1en_HK
dc.identifier.epage10en_HK
dc.identifier.isiWOS:000228482400003-
dc.publisher.placeUnited Statesen_HK
dc.identifier.scopusauthoridLi, H=35769216800en_HK
dc.identifier.scopusauthoridJiao, JJ=7102382963en_HK

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