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Slope evolution and slope stability, Kawarau valley, Central Otago, New Zealand

  • Bell D. H. 
Section 13 Engineering Geology

Summary

Slopes developed within the Kawarau Valley in response to Late Pleistocene fluvial, glacial and periglacial processes, with localised slope failures continuing during Holocene times. Rock mass anisotropy within the basement chlorite schists has been a major influence in geomorphic development, and extensive mass movement deposits now mantle the valley slopes. A chronology of events is presented, based in part on radiocarbon dating and pollen analysis, and geological and geotechnical aspects of slope instability are reviewed with reference to particular landslide areas. Slope evolution within the Kawarau Valley has major engineering and environmental implications, and these are discussed in relation to proposed hydro-electric development, roading and land use. Quantitative assessment of the stability of both rock and soil slopes must take account of the complex geological controls of slope development, and investigation methods are outlined.

Keywords

Mass Movement Slope Failure Rock Slope Landslide Area Wedge Failure 

Évolution Des Pentes Et Stabilite Des Pentes, Vallée Du Kawarau, Otago Central, Nouvelle-Zéalande

Résumé

Dans la vallée du Kawarau, à la fin du Pléistocène, des processus fluviatiles, glaciaires et périglaciaires ont abouti à la formation de pentes qui présentent des ruptures localisées d’âge holocène. L’anisotropie du massif rocheux dans les chloritoschistes de base a eu une influence primordiale sur la formation du modelé, et actuellement, les pentes de la vallée sont recouvertes par de vastes dépôts dûs à des mouvements de masses. On présente la chronologie des événements, basée d’une part sur la datation au radiocarbone et d’autre part sur l’étude palynologique; puis les aspects géologiques et géotechniques de l’instabilité des pentes sont passés en revue, avec référence à des régions particulières où des glissements de terrain on été observés. L’évolution des pentes dans la vallée du Kawarau a des implications importantes pour les constructions et pour l’environnement: elles sont discutées à propose de projets hydroélectriques, routiers et d’utilisation du sol. Des évaluations quantitatives de la stabilité des roches et des sols en pente doivent tenir compte des facteurs géologiques complexes qui ont formé ces pentes; on donne une esquisse des méthodes d’investigation.

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Copyright information

© International Association of Engineering Geology 1976

Authors and Affiliations

  • Bell D. H. 
    • 1
  1. 1.Geology DepartmentUniversity of CanterburyChristchurchNew Zealand

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