PROJECT 3.2: THE INFLUENCE OF GROUNDWATER AND SURFACE WATER ON WATER
QUALITY
(Prof R Volker, UQ & Prof A Johnston, JCU)
The primary goal of the project is to quantify the groundwater and wastewater
discharge contributions to the nutrient (specifically nitrogen and phosphorus)
budget of the Great Barrier Reef lagoon. It is also assessing the groundwater
resources of coastal islands and developing sustainable management
strategies to ensure that resources are used without affecting water quality.
Information associated with the high island sites has been cited and
evaluated. Numerical modelling work has modified an explicit finite difference
model for water and solute movement in the unsaturated zone, yielding
improved accuracy by reducing numerical dispersion. This allows efficient
simulation of nitrate movement at a number of locations with different
soil profiles. Phosphate has been given a lesser priority as discussions
with soil chemists indicate that the more important threat to adjacent
marine systems is from nitrates in the waste-water.
The High Island (Brampton Island) study has progressed to a stage where
a water monitoring program is in place and a preliminary nutrient budget
has been developed.
The Coral Island (Heron Island) study with the University of Queensland
has provided understanding of groundwater quality on the island and an
existing model (SUTRA), which simulates the groundwater-seawater interface
in an island situation, is being modified to address the smaller time-frame
response related to tidal changes. Future work includes the establishment
of instrumentation and sampling programs.
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