Detection of Groundwater Discharge to Aquatic and Marine Environments using Thermal Infrared within a Karst Landscape.

Darren Herpich

    Research output: ThesisMasters Thesis

    80 Downloads (Pure)

    Abstract

    The discharge of groundwater to oceans, springs, lakes and rivers is an
    important part of the hydrological cycle in the South East of South Australia.
    Discharge to the nearshore and offshore marine environment is termed
    Submarine Groundwater Discharge (SGD) whilst discharge to aquatic
    environments (riverine and terrestrial rising springs) is termed Groundwater
    Discharge (GD). Understanding where, and at what rate, fresh groundwater
    discharges from the limestone aquifer, will enable regulatory agencies to
    develop appropriate water allocation plans to sustainably manage groundwater
    resources and associated ecosystems. However, only a few of the known GD
    and SGD sites associated with the unconfined Tertiary Limestone Aquifer
    (TLA) in the aquatic and marine environments of South East South Australia
    are confirmed GD / SGD. These include a few terrestrial rising springs,
    outflowing streams at the base of river cliffs and beach springs in the nearshore
    marine environment.

    This study has shown that analysis of thermal infrared imagery can detect
    thermal contrasts between discharging groundwater and the receiving
    environment. Airborne thermal imagery was used to identify 44 thermal
    anomalies. Thirty seven of these occurred within aquatic environments whilst
    seven anomalies occurred in the marine environment. Twenty three of these
    (18 aquatic and 5 marine) were verified as GD / SGD sites through collection
    of field measurements including salinity and temperature. No ground-truthing
    information was collected at the remaining sites.

    Older satellite thermal imagery including Landsat 5 TM and ASTER failed to
    detect anomalies in the locations revealed by the airborne thermal infrared
    imagery, due largely to issues with spatial resolution. However, recent imagery
    from the Landsat 8 satellite with its improved radiometric resolution
    successfully detected variations in temperature associated with the only
    offshore anomaly detected by airborne thermal imagery.

    The use of multispectral imagery covering the Visible and Near Infrared was
    largely unsuccessful for the identification of GD / SGD anomaly sites with the
    exception of two anomalies where unique spectral signatures associated with
    turbid and plant laden water allowed partial classification of the anomalies from
    surrounding waters. Given the results only partially replicated the geometry of
    the two sites the use of high resolution multispectral imagery could not be
    recommended for large-scale exploration of GD / SGDs.

    This study concludes that given the size of GD / SGDs in the South East of
    South Australia the recommended technique to successfully identify GD in the
    aquatic environments and SGD in the marine environments is high resolution
    airborne thermal infrared imagery. The preferred seasonal window for data
    acquisition was identified for the ocean and river environments as June through
    to August when the groundwater was typically warmer than the receiving
    environments.
    Original languageEnglish
    QualificationMaster of Applied Science
    Awarding Institution
    • Charles Sturt University
    Supervisors/Advisors
    • Dehaan, Remy, Co-Supervisor
    • Wilson, Andrea, Co-Supervisor
    Award date21 Aug 2015
    Place of PublicationAustralia
    Publisher
    Publication statusPublished - 2015

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