Edad del agua subterránea, flujo y mezcla de caudales en el entorno de grandes minas a cielo abierto, región de Pilbara, noroeste de Australia

Translated title of the contribution: Groundwater age, mixing and flow rates in the vicinity of large open pit mines, Pilbara region, northwestern Australia

Peter Cook, Shawan Dogramaci, James McCallum, Joanne Hedley

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Determining groundwater ages from environmental tracer concentrations measured on samples obtained from open bores or long-screened intervals is fraught with difficulty because the sampled water represents a variety of ages. A multi-tracer technique (Cl, 14C, 3H, CFC-11, CFC-12, CFC-113 and SF6) was used to decipher the groundwater ages sampled from long-screened production bores in a regional aquifer around an open pit mine in the Pilbara region of northwest Australia. The changes in tracer concentrations due to continuous dewatering over 7 years (2008–2014) were examined, and the tracer methods were compared. Tracer concentrations suggest that groundwater samples are a mixture of young and old water; the former is inferred to represent localised recharge from an adjacent creek, and the latter to be diffuse recharge. An increase in 14C activity with time in wells closest to the creek suggests that dewatering of the open pit to achieve dry mining conditions has resulted in change in flow direction, so that localised recharge from the creek now forms a larger proportion of the pumped groundwater. The recharge rate prior to development, calculated from a steady-state Cl mass balance, is 6 mm/y, and is consistent with calculations based on the 14C activity. Changes in CFC-12 concentrations with time may be related to the change in water-table position relative to the depth of the well screen.

Translated title of the contributionGroundwater age, mixing and flow rates in the vicinity of large open pit mines, Pilbara region, northwestern Australia
Original languageSpanish
Pages (from-to)39-53
Number of pages15
JournalHydrogeology Journal
Volume25
Issue number1
DOIs
Publication statusPublished - 1 Feb 2017
Externally publishedYes

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