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

Darren Herpich

Research output: ThesisMasters Thesis

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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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