Defining the stable isotope composition of rainfall for groundwater studies in Australia

Hughes, CE; Hollins, SE; Crawford, J; Meredith, KT; Parkes, SD

Defining the stable isotope composition of rainfall for groundwater studies in Australia

Date

2013-09-19

Authors

Publisher

International Association of Hydrogeologists

Abstract

The stable isotopes of water, d2H and d18O, are conservative tracers available for studying mixing of water in the hydrosphere. But they are not completely conservative as they undergo fractionation as a result of hydrological processes such as evaporation, precipitation, ice and snow formation and melting, and geothermal activity. The fractionation can be used to understand the provenance and history of groundwater and to define end members for mixing studies. Measurements of stable water isotopes in Australian rainfall have been made monthly at six coastal sites and Alice Springs since 1962 as part of the Global Network of isotopes in Precipitation (GNIP). Since 2006 this network has been expanded to include seven inland sites in New South Wales, Queensland, South Australia and Western Australia. in addition, event-based studies have been conducted at four locations in the Sydney region since 2005. These data have been analysed to determine local meteoric water lines, weighted averages and to investigate the relationships between rainfall isotopic composition, temperature and precipitation amount. For one Sydney region location, Mt Werong, the effect of moisture source, rainout and the prevailing synoptic conditions were investigated on an event basis over four years from 2005 and 2009. We will present results from these studies as well as a precipitation weighted method for determining a meteoric water line that is particularly applicable to areas with hot dry summers and wet winters such as SW Western Australia.

Keywords

Stable isotopes, Rain, Ground water, Australia, Evaporation, Ice, Snow, Climates

Citation

Hughes, C., Hollins, S., Crawford, J., Meredith, K., & Parkes, S. (2013). Defining the stable isotope composition of rainfall for groundwater studies in Australia. Paper presented to IAH 2013 Perth Australia : "Solving the groundwater challenges of the 21st century", International Association of Hydrogeologists 40th International Conference, Perth, Western Australia, 15-20 September 2013. (pp. 163).