Journal
HYDROGEOLOGY JOURNAL
Volume 25, Issue 1, Pages 39-53Publisher
SPRINGER
DOI: 10.1007/s10040-016-1467-y
Keywords
Groundwater age; Mining; Groundwater recharge/water budget; Australia
Categories
Funding
- Australian Research Council [LP150100395]
- Rio Tinto Iron Ore
- Australian Research Council [LP150100395] Funding Source: Australian Research Council
Ask authors/readers for more resources
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, C-14, H-3, 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 C-14 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 C-14 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.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available