A groundwater salinity hotspot and its connection to an intermittent stream identified by environmental tracers (Mt Lofty Ranges, South Australia)

Tom Anderson, Erick Bestland, Lesja Soloninka, Ilka Wallis, Edward Banks, Markus Pichler

    Research output: Contribution to journalArticle

    2 Citations (Scopus)

    Abstract

    High and variable levels of salinity were investigated in an intermittent stream in a high-rainfall area (∼800 mm/year) of the Mt. Lofty Ranges of South Australia. The groundwater system was found to have a local, upslope saline lens, referred to here as a groundwater salinity ‘hotspot’. Environmental tracer analyses (δ18O, δ2H, 87/86Sr, and major elements) of water from the intermittent stream, a nearby permanent stream, shallow and deep groundwater, and soil-water/runoff demonstrate seasonal groundwater input of very saline composition into the intermittent stream. This input results in large salinity increases of the stream water because the winter wet-season stream flow decreases during spring in this Mediterranean climate. Furthermore, strontium and water isotope analyses demonstrate: (1) the upslope-saline-groundwater zone (hotspot) mixes with the dominant groundwater system, (2) the intermittent-stream water is a mixture of soil-water/runoff and the upslope saline groundwater, and (3) the upslope-saline-groundwater zone results from the flushing of unsaturated-zone salts from the thick clayey regolith and soil which overlie the metamorphosed shale bedrock. The preferred theory on the origin of the upslope-saline-groundwater hotspot is land clearing of native deep-rooted woodland, followed by flushing of accumulated salts from the unsaturated zone due to increased recharge. This cause of elevated groundwater and surface-water salinity, if correct, could be widespread in Mt. Lofty Ranges areas, as well as other climatically and geologically similar areas with comparable hydrogeologic conditions.

    Original languageEnglish
    Pages (from-to)2435-2451
    Number of pages17
    JournalHydrogeology Journal
    Volume25
    Issue number8
    DOIs
    Publication statusPublished - 1 Dec 2017

    Keywords

    • Australia
    • Environmental tracers
    • Groundwater/surface-water relations
    • Salinization
    • Sr isotopes

    Fingerprint Dive into the research topics of 'A groundwater salinity hotspot and its connection to an intermittent stream identified by environmental tracers (Mt Lofty Ranges, South Australia)'. Together they form a unique fingerprint.

    Cite this