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Article: Numerical study of airflow in the unsaturated zone induced by sea tides

TitleNumerical study of airflow in the unsaturated zone induced by sea tides
Authors
Issue Date2008
PublisherAmerican Geophysical Union.
Citation
Water Resources Research, 2008, v. 44 n. 6, p. 1-13 How to Cite?
AbstractThe air pressures in coastal unsaturated zones fluctuate in response to tidal fluctuations. Two-phase air-water flow induced by sea tides in a coastal two-layered subsurface system is investigated through numerical simulations. The system consists of upper and lower layers with permeabilities of kU and kL, respectively. A water table exists in the lower layer. The study demonstrates that airflow in the unsaturated zone is controlled by permeabilities of both layers and the fluctuation of water level. The tide-induced water level fluctuation may result in significant air pressure fluctuation in the unsaturated zone in an air-confined system; that is, the permeability of the upper layer is about 2 orders of magnitude lower than that of the lower layer. In such an air-confined system, horizontal airflow is dominant in the lower layer and vertical airflow is dominant in the upper layer. The simulation results show that the hydraulic head, rather than the sea tide, is the direct driving force of the air pressure fluctuation above the water table. The study on the relation between the air pressure amplitude and the landward distance demonstrates that the air pressure amplitudes increase to a maximum and then decrease with distance. The amplitude of air pressure fluctuation decreases progressively with kU in the lower layer. In the upper layer, however, the amplitude tends to increase with kU when kU is very low and decrease with kU when k U is relatively high. Overall, the air flux fluctuations across the atmosphere-soil interface attenuate landward gradually, and this attenuation becomes faster as the permeability of the upper layer increases. Copyright 2008 by the American Geophysical Union.
Persistent Identifierhttp://hdl.handle.net/10722/151255
ISSN
2015 Impact Factor: 3.792
2015 SCImago Journal Rankings: 2.661
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorGuo, HPen_US
dc.contributor.authorJiao, JJen_US
dc.date.accessioned2012-06-26T06:19:27Z-
dc.date.available2012-06-26T06:19:27Z-
dc.date.issued2008en_US
dc.identifier.citationWater Resources Research, 2008, v. 44 n. 6, p. 1-13en_US
dc.identifier.issn0043-1397en_US
dc.identifier.urihttp://hdl.handle.net/10722/151255-
dc.description.abstractThe air pressures in coastal unsaturated zones fluctuate in response to tidal fluctuations. Two-phase air-water flow induced by sea tides in a coastal two-layered subsurface system is investigated through numerical simulations. The system consists of upper and lower layers with permeabilities of kU and kL, respectively. A water table exists in the lower layer. The study demonstrates that airflow in the unsaturated zone is controlled by permeabilities of both layers and the fluctuation of water level. The tide-induced water level fluctuation may result in significant air pressure fluctuation in the unsaturated zone in an air-confined system; that is, the permeability of the upper layer is about 2 orders of magnitude lower than that of the lower layer. In such an air-confined system, horizontal airflow is dominant in the lower layer and vertical airflow is dominant in the upper layer. The simulation results show that the hydraulic head, rather than the sea tide, is the direct driving force of the air pressure fluctuation above the water table. The study on the relation between the air pressure amplitude and the landward distance demonstrates that the air pressure amplitudes increase to a maximum and then decrease with distance. The amplitude of air pressure fluctuation decreases progressively with kU in the lower layer. In the upper layer, however, the amplitude tends to increase with kU when kU is very low and decrease with kU when k U is relatively high. Overall, the air flux fluctuations across the atmosphere-soil interface attenuate landward gradually, and this attenuation becomes faster as the permeability of the upper layer increases. Copyright 2008 by the American Geophysical Union.en_US
dc.languageengen_US
dc.publisherAmerican Geophysical Union.-
dc.relation.ispartofWater Resources Researchen_US
dc.rightsWater Resources Research. Copyright © American Geophysical Union.-
dc.titleNumerical study of airflow in the unsaturated zone induced by sea tidesen_US
dc.typeArticleen_US
dc.identifier.emailJiao, JJ: jjiao@hku.hken_US
dc.identifier.authorityJiao, JJ=rp00712en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1029/2007WR006532en_US
dc.identifier.scopuseid_2-s2.0-49449092655en_US
dc.identifier.hkuros153038-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-49449092655&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume44en_US
dc.identifier.issue6en_US
dc.identifier.eissn1944-7973-
dc.identifier.isiWOS:000256571000003-
dc.publisher.placeUnited Statesen_US
dc.identifier.scopusauthoridGuo, HP=25226459100en_US
dc.identifier.scopusauthoridJiao, JJ=7102382963en_US

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