February
26, 2007
CSIRO
IMAGERY SHOWS OUTER GREAT BARRIER
REEF AT RISK FROM RIVER PLUMES
Remotely
sensed images, taken from February 9 to 13, challenge conventional
thought that
sediment traveling from our river systems into the GBR is captured by
the
longshore current and travels no more than 10 to 15 kilometers
offshore,
affecting only the inner Great Barrier Reef Lagoon and the inner reef
corals.
Images
captured by CSIRO show large plumes of terrestrial material following
unconventional patterns and traveling quite fast as far as 65 to 130
kilometers, to the outer reef and, in some instances, traveling along
the outer
reef and re-entering the reef.
The
plumes are the result of heavy rainfalls in northern QLD around late
January to
early February 2007, with the resulting flood waters carrying a larger
sediment
load than during regular rainfall and river flow. As such floods have
not
occurred for a while the accumulated material in the creeks ands rivers
coupled
with increased sediment runoff from the land is causing a
significant
transport of terrestrial material to all areas of the affected reefs
and reef
waters.
Managers
of the GBR have long been examining the effects of run-off of
sediments, including
pesticides, herbicides and fertilizers, on the reef corals.
The
images challenge the traditional school of hydrological modeling, which
says
sediment plume movement in the mid to northern GBR usually go
north and
never directly flow to the outer reef is spared the direct
effects of
such river floods.
“A
re-think is needed now that we know where flood plumes go,”
says CSIRO
scientist Arnold Dekker, ”and what this means as organic
micro-pollutants may
be traveling to parts of the reef scientists hadn’t thought
to look before.”
The
images were taken from NASA’s MODIS satellite by GeoScience Australia’s Alice Springs
site for a new product being developed by the Wealth from Oceans
Flagship to
track coastal and ocean events in real-time, building on the technology
behind
the successful SENITEL bushfire tracking system.
While
extreme coastal events have been captured by remote sensing before,
this is the
first time they can be seen and analyzed straight after the event as
there are
now more satellites imaging the Earth and CSIRO has invested in fast
information delivery systems.
The
images answer many of the questions posed in the article
‘Cattle, Crops and
Coral: Flood Plumes and the Great
Barrier Reef’
from the 2006 NASA EOS Annual Report.
##
Contact:
Leane
Regan
CSIRO Australia
61-262-464-546
leane.regan@csiro.au
This
text derived from:
http://www.csiro.au/news/ps2t8.html
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