on our ARC Project..
"LP4455080_ Restoring hydrological connectivity of surface
waters and groundwaters: biogeochemical processes and environmental
benefits for river landscapes."
The aim of our ARC project has been to examine the application
of NSF for improving the sustainability and function of river
landscapes. The function of the landscape in this case being
the provision of high quality aquatic and riparian habitat,
improved security of surface waters, and enhanced connectivity
of surface waters and ground waters. Key aspects of our proposal
have been completed ahead of schedule, with startling results.
The significance of these results is reflected in the invitation
to present our research in two oral papers at the upcoming "5th
Australian Stream Management Conference" to be held in
Albury, May 22nd-25th. The ABC science program Catalyst, will
also be featuring our research during May.
Over the past 4 months the research team have been finalising
a number of the key monitoring aspects of our NSF project at
Baramul. The project commenced two and half years ago and the
results are curiously outstanding. We have been surprised by
how fast the riverine corridor has responded to the NSF initiative.
Our key observations and their significance are:
1) The dramatic recovery of riparian vegetation
through the treatment reach at Baramul. Conditions along the
stream appear to strongly promote the colonisation of the stream
banks, lower floodplain and benched within the channel with
Casuarina (she-oak). There is evidence of the native vegetation
out-completing the exotic vegetation and in many reaches the
Willow, which was introduced and planted on a large scale by
the state govt., is being replaced by the native vegetation.
The colonization is so prolific, many areas where we conducted
channel terrain surveys only 12 months ago, are now entirely
2) There has been the development of channel
features indicative of a stream undergoing incredible recovery
within and immediately downstream of the NSF treatment reach.
These landforms include the development of substantial channel
bars and benches, the development of pools, rifles and low flow
meandering runs (shallow connecting flows). Historical records
tell us that such landforms were once common in the Widen Brook,
but like so many other degraded streams, it has been totally
lost through channel erosion.
The recovery of these channel features is most dramatic immediately
downstream of the NSF structures (7 major structures in total),
this demonstrates the compounding benefit of an integrated NSF
system. The conclusion is that "scale" and the integration
of multiple NSF structures can be optimised. Further testing
of NSF over a number of implementation scales would be useful
for optimising investment vs. landscape improvement.
3) Surface water resources have persisted
in the stream and pools in the NSF treatment reach whereas surface
water has been absent both in the non-NSF treated areas upstream
and down stream. This is significant given that last year Baramul
received just 400mm of rainfall, far below the 700 mm average
for the Widden catchment. The enhanced availability of surface
waters in the NSF treatment reach is puzzling, although predicted
by Peter Andrews.
We have tested a number of hypotheses including high spatial
resolution mapping of bed-rock to determine if bed-rock confinement
was a factor. It was not. Next week we will be testing additional
aspects of groundwater recharge/discharge through detailed pump
tests of groundwater bores
4) Groundwater-surface water monitoring clearly
shows that NSF is enhancing the connectivity of the stream flow
with floodplain shallow alluvial aquifers. A major issue raised
by the 2002 CSIRO report was the potential for this enhanced
connectivity to increase salinisation.
Our monitoring, including detailed and highly sensitive continuous
monitoring of groundwaters and surface waters in very close
proximity to the stream, have not detected a measurable change
in the prevailing salinity of either the groundwaters or the
surface waters in the NSF treatment reach.
5) Macro invertebrates are a tremendous indicator
for water quality and aquatic health. Our industry partners
(NSW Dept of Environment) have conducted two annual surveys
so far following the AusRivas national protocol and have reported
far greater diversity within the NSF study reach, a diversity
that is equivalent to that found in the very upper pristine
reaches of Widden Brook, deep within the Wollombi National Park.
The significant diversity and abundance of macro invertebrate
in the NSF treatment reach has been attributed to the development
of a connected and relatively stable aquatic habitat. The availability
of surface waters, diversity in habitat types (pools-riffles-runs
that are absent elsewhere in Widden Brook) and the healthy riparian
vegetation are important factors contributing to the diversity
and abundance of macro invertebrates within the NSF treatment
reach. This is a very positive tick of environmental improvement.
The final survey is to be conducted in the coming months.
The NSF system is producing some remarkable improvements
to the sustainability and function of the riverine landscape
at Baramul. These results are very interesting and indicate
a great potential for similar benefits in other landscape settings
and agriculture production systems.
However, the ARC Project because of its very narrow
focus on river management is obviously no substitute for the
WaterSmart Landscape Rehydration Project. The National Water
Commissions' Landscape Rehydration Project bid offers a great
opportunity to apply NSF and gain benefits at a significant
environmental, social and economic scale, crossing many agricultural
Dr Richard Bush
Australian Research Fellow of the Australian Research Council
Co-Director of Centre for Acid Sulfate Soil Research School
of Environmental Science and Management Southern Cross University,
Lismore, NSW, 2480.
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