Investigation of δ18O and δ2H in the Namoi River catchment - elucidating recharge sources and the extent of sur-face water/groundwater interaction
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Date
2008-10-26
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Abstract
Stable isotopes 18O and 2H were analysed in water samples from rainfall, surface water and groundwater within the semi-arid Namoi River catchment in NSW, Australia.The isotopic composition of rainfall events and groundwater samples plot along the Local Meteoric Water Line (LMWL). In contrast, the surface water samples of the Namoi River clearly show signs of evaporative enrichment and plot on a Local Evaporation Line (LEL) constructed for the area based on δ18O and δ2H time-series for surface waters of the Namoi River. The river samples have a distinctly lower slope than the LMWL which is due to evaporation. Shallow groundwater near the Namoi River shows considerable enrichment compared to average groundwater signatures and plots in between the LMWL and the LEL on a δ2H vs. δ18O graph. These results clearly indicate that the Namoi River is recharging the shallow aquifer system. Conversely, the isotopic composition of surface water in the tributaries of Maules and Horsearm creeks are similar to groundwater indicating that these creeks are receiving groundwater discharge. This study reveals many complex hydrological processes occurring in the catchment. It would not have been possible to elucidate these processes without the use of stable isotope data. © Authors
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Australia, New South Wales, Rivers, Isotopes, Ground water, Arid lands, Watersheds, Rain water, Evaporation
Citation
Andersen, M.S., Meredith, K., Timms, W., & Acworth, R.I. (2008). Investigation ofδ18Oandδ2Hin the Namoi River catchment - elucidating recharge sources and the extent of surface water/groundwater interaction. Paper presented to the 36th Congress of International Association of Hydrogeologists
(IAH): Integrating Groundwater Science and Human Wellbeing,
26‐31 October 2008, Toyama, Japan.