Precipitation stable isotopes δ²H and δ¹⁸O in the Sydney Basin

Stable water isotopes δ ²H and δ¹⁸O are increasingly considered a standard parameter to be analysed in groundwater sampling, and are also considered useful in studies of surface waters and land surface processes. They may be used in determining water sources and mixing relationships, as well as being an indicator of evaporation. An important parameter for hydrological studies using stable water isotopes is the composition of the precipitation input. Four years of event based or weekly precipitation samples were collected and analysed for stable water isotopes δ²H and δ¹⁸O at four sites around the Sydney Basin: Lucas Heights, Mt Werong, Lithgow and Big Hill. These data have been used to determine weighted average values, meteoric water lines and investigate seasonal, event size and geographical effects on isotopic composition. Air parcel back trajectories, together with rainfall and humidity along the back trajectories, and mean sea level pressure maps (MSLP) are used to identify conditions associated with isotopically depleted and isotopically enriched rainfall samples at Mt Werong.