Abstract

GONZALEZ, Maria Alejandra; BAUMANN, Valèrie  and  JACKSON JR., Lionel E.. Investigation of the 2007 flows from Chalala and Coquena, Purmamarca, Jujuy Province. Rev. Asoc. Geol. Argent. [online]. 2009, vol.65, n.4, pp.791-804. ISSN 0004-4822.

This work presents the results of the investigation of mudflows from Quebrada de Coquena of 7 March, 2007 and from Quebrada de Chalala of 29 March of the same year. These stream basins are tributary to the Quebrada de Purmamarca located in the Cordillera Oriental, Jujuy Province, Argentina. The studies focussed on the classification of the type of mass flow type and quantification of the magnitude of these events. Flow velocity was calculated using two different equations. Both methods produced similar results. Flow volume was measured directly in the field. The relationship between the total discharge (V) and the peak flow (Q_p) was estimated by using equations for similar flows from the geotechnical literature. Maximum erosional yield was estimated using the JICA method. The probability of large destructive mudflows inundating the fans of these streams is very high (>1/20) and their magnitude is class 5: a volume greater than 10⁵ m³. The flow velocity, volume and frequency calculated in this study are valuable for hazard mapping, the creation and placement of infrastructure, and land use planning.

Keywords : Volume calculation; Velocity calculation; Mud flow; Debris flow.

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