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Article: Confined groundwater near the rockhead in igneous rocks in the Mid-Levels area, Hong Kong, China

TitleConfined groundwater near the rockhead in igneous rocks in the Mid-Levels area, Hong Kong, China
Authors
KeywordsArtesian groundwater
Confined aquifer
Hydraulic conductivity
Hydrogeology
Rockhead
Saprolite
Weathered igneous rock
Issue Date2006
PublisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/enggeo
Citation
Engineering Geology, 2006, v. 84 n. 3-4, p. 207-219 How to Cite?
AbstractIt is customary in Hong Kong to assume that the hydraulic conductivity of weathered igneous rocks decreases with depth or as the rock mass becomes less weathered. Such a hydraulic conductivity pattern can only lead to an unconfined aquifer. This paper presents a case study in the regions in and around the Mid-Levels area in Hong Kong regarding a possible relatively high hydraulic conductivity (K) zone and confined groundwater along the rockhead. The Mid-Levels area is located at the lower part of the north-facing slopes of Victoria Peak on Hong Kong Island and is prone to landslides. Although this site has a long history of geotechnical studies because of extensive urban development along the coast and public concern on slope stability, hydrogeology of the site remains poorly understood. This paper reexamined the hydraulic conductivity data in 7 boreholes conducted in the 1970s and found that 4 of them indicate an increase in K at the rockhead. Groundwater conditions revealed by tunnel construction at the coast suggest that K close to the rockhead is about 10 times greater than above rockhead. A careful analysis of storm response of a piezometer group with tips in different depths indicates that there was an upward flow from the bedrock to the colluvium. A field study of two overflow standpipes conducted by the authors showed that the water level can be 0.64 and 3.73 m above the ground surface, which illustrates that the deep groundwater is significantly artesian. A search of the archived site investigation reports from the government and private companies has led to an identification of about 24 sites with overflow boreholes, which suggests that overflow phenomenon is quite common in the study area. The paper then concludes that in the study area there is a relatively high K zone along the rockhead and the groundwater in the zone is confined. It is recommended that geotechnical engineers should carry out a more careful field study on an overflow borehole because such a borehole indicates a confined groundwater condition important for slope stability study and foundation design. © 2006 Elsevier B.V. All rights reserved.
Persistent Identifierhttp://hdl.handle.net/10722/72813
ISSN
2015 Impact Factor: 2.196
2015 SCImago Journal Rankings: 1.810
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorJiao, JJen_HK
dc.contributor.authorDing, Gen_HK
dc.contributor.authorLeung, CMen_HK
dc.date.accessioned2010-09-06T06:45:20Z-
dc.date.available2010-09-06T06:45:20Z-
dc.date.issued2006en_HK
dc.identifier.citationEngineering Geology, 2006, v. 84 n. 3-4, p. 207-219en_HK
dc.identifier.issn0013-7952en_HK
dc.identifier.urihttp://hdl.handle.net/10722/72813-
dc.description.abstractIt is customary in Hong Kong to assume that the hydraulic conductivity of weathered igneous rocks decreases with depth or as the rock mass becomes less weathered. Such a hydraulic conductivity pattern can only lead to an unconfined aquifer. This paper presents a case study in the regions in and around the Mid-Levels area in Hong Kong regarding a possible relatively high hydraulic conductivity (K) zone and confined groundwater along the rockhead. The Mid-Levels area is located at the lower part of the north-facing slopes of Victoria Peak on Hong Kong Island and is prone to landslides. Although this site has a long history of geotechnical studies because of extensive urban development along the coast and public concern on slope stability, hydrogeology of the site remains poorly understood. This paper reexamined the hydraulic conductivity data in 7 boreholes conducted in the 1970s and found that 4 of them indicate an increase in K at the rockhead. Groundwater conditions revealed by tunnel construction at the coast suggest that K close to the rockhead is about 10 times greater than above rockhead. A careful analysis of storm response of a piezometer group with tips in different depths indicates that there was an upward flow from the bedrock to the colluvium. A field study of two overflow standpipes conducted by the authors showed that the water level can be 0.64 and 3.73 m above the ground surface, which illustrates that the deep groundwater is significantly artesian. A search of the archived site investigation reports from the government and private companies has led to an identification of about 24 sites with overflow boreholes, which suggests that overflow phenomenon is quite common in the study area. The paper then concludes that in the study area there is a relatively high K zone along the rockhead and the groundwater in the zone is confined. It is recommended that geotechnical engineers should carry out a more careful field study on an overflow borehole because such a borehole indicates a confined groundwater condition important for slope stability study and foundation design. © 2006 Elsevier B.V. All rights reserved.en_HK
dc.languageengen_HK
dc.publisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/enggeoen_HK
dc.relation.ispartofEngineering Geologyen_HK
dc.rightsEngineering Geology. Copyright © Elsevier BV.en_HK
dc.subjectArtesian groundwateren_HK
dc.subjectConfined aquiferen_HK
dc.subjectHydraulic conductivityen_HK
dc.subjectHydrogeologyen_HK
dc.subjectRockheaden_HK
dc.subjectSaproliteen_HK
dc.subjectWeathered igneous rocken_HK
dc.titleConfined groundwater near the rockhead in igneous rocks in the Mid-Levels area, Hong Kong, Chinaen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0013-7952&volume=84&issue=3-4&spage=207&epage=219&date=2006&atitle=Confined+groundwater+near+the+rockhead+in+igneous+rocks+in+the+Mid-Levels+area,+Hong+Kong,+Chinaen_HK
dc.identifier.emailJiao, JJ:jjiao@hku.hken_HK
dc.identifier.authorityJiao, JJ=rp00712en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1016/j.enggeo.2006.02.006en_HK
dc.identifier.scopuseid_2-s2.0-33748640620en_HK
dc.identifier.hkuros120786en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-33748640620&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume84en_HK
dc.identifier.issue3-4en_HK
dc.identifier.spage207en_HK
dc.identifier.epage219en_HK
dc.identifier.isiWOS:000238132600007-
dc.publisher.placeNetherlandsen_HK
dc.identifier.scopusauthoridJiao, JJ=7102382963en_HK
dc.identifier.scopusauthoridDing, G=24467315600en_HK
dc.identifier.scopusauthoridLeung, CM=35146017000en_HK

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