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THE RIVERS
Most of the rivers in the Murray-Darling Basin flow over
plains and many of these only carry water in times of flood.
The Darling River, Murray River and the Murrumbidgee River
are the three longest rivers in the Murray-Darling Basin
and Australia. |
The
River Murray is 2530 km long from the Snowy
Mountains on the New South Wales - Victoria
Border to the
Southern Ocean in South Australia. The headwaters
comprise less than 2 per cent of the Murray-Darling
Basin, but contribute nearly 40 per cent of
the inflow to the Murray River. The flow in
the Murray
is very low by world standards. Its annual
average flow would pass through the Amazon
in less than
a day. |
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| The
Murray like the Darling also has a highly variable
flow and in the early 1900’s construction
of locks and weirs began and the result is a
more regulated river. |
| The
Darling River is the longest
river in Australia measuring 2740 kilometres
from
its sources to its confluence
with the Murray at Wentworth. The main source of
the Darling is usually considered to be the Severn,
which becomes successively the Dumaresq, Macintyre,
Barwon, and, finally, the Darling. Discharge of
the lower tributaries (Culgoa, Warrego, Paroo,
Gwydir, Namoi, Macquarie, and Bogan) of the main
stream fluctuates as a result of droughts and floods.
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| Because
much of the Darling's course runs through extensive
saltbush pastures, receiving an average of less
than 250 mm (10 in.) of rain annually, the river
often loses more water by evaporation than is
gained from its tributaries, many of which sometimes
fail to reach the main stream. |
| The
Murrumbidgee River flows for 1,600 km and
begins in the Kosciusko National Park in NSW.
It plays host to 14 major dams and 8 large weirs.
The Snowy Mountains Hydro Electric Scheme assists
with regulating water flow and supplying the
10,000 kms of irrigation channels. |
A
Floodplain is
that area of relatively flat land covered by
water during a major flood. It is built, layer
upon layer, of nutrient-rich sediment deposited
by the river during floods. This activity results
in a complex of terraces, hollows, wetlands, billabongs,
backwaters and anabranches. Floodplains are a vital
part of the river ecosystem. They are nature’s
water treatment works, removing vast quantities
of pollutants from inland river waters. They also
act as a buffer zone, nursery and are the major
centres of biological life in the river ecosystem.
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| A
Wetland is
defined as land that is inundated with shallow,
slow moving or stationary water, on a temporary
or permanent basis, that may be fresh, brackish
or saline. The major difference between a floodplain
and a wetland is wetlands are permanently or temporarily
covered by water, whereas floodplains are only
covered with water in times of floods.The Murray-Darling
Basin supports over 30 000 wetlands. Ten of these
wetlands are of international significance and
listed as Ramsar Wetlands. |
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The
Basin's Wetlands are
among its most productive and biologically
diverse ecosystems, providing
the essential breeding and feeding habitats for
many species of waterbirds, fish, invertebrates
and plants.
The South Australian wetlands in the Murray-Darling
Basin that are of international importance & listed
under Ramsar Convention are the Coorrong/Lake Alexandrina
and Albert; and the Riverland including Chowilla
floodplain system. |
The
Murray - Darling Basin contains
diverse flora and fauna, many of which are
unique to the area.
Native flora and fauna are important to the environment
because of their ability to adapt to the natural
conditions. However many of the conditions have
changed due to the introduction of exotic species.
Therefore native and introduced plants and animals
now exist side by side. |
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challenge is to ensure that they can continue
to do so in a way that improves the health of
the whole Murray-Darling Basin system. |
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Captain
Cook Cruises - Murray River Destination Information
