13.6.3
How does water flow across the land?
Permanent rivers and streams flow in only a small proportion of the Australian continent. Australia is the driest inhabited continent. It has: • the least amount of run-off • the lowest percentage of rainfall as run-off • the least amount of water in rivers
FIGURE6 Lake Argyle is one of Australia’s largest freshwater man-made reservoirs by volume.
• the smallest area of permanent wetlands • the most variable rainfall and stream flow. Australia has many lakes and drainage basins
(see FIGURE7 ) but many hold little water compared with those found on other continents. The largest drainage basins are in the tropical north, far from major population centres.
SkillBuilder discussion Communication 1. Some drainage basins are located in more than one state. What impact might this have on the management of these basins? 2. Identify the drainage basins that receive the highest and lowest amounts of run-off. 3. Suggest reasons to explain why drainage basins in the north have higher levels of run-off than those in the south.
FIGURE7 Australia’s drainage basins
Timor Sea
23.3%
Gulf of Carpentaria
23.3%
North-east Coast
Lake Eyre
1.6%
21.1%
Indian Ocean
Western Plateau
1.0%
0.4%
Bulloo– Bancannia
0.3%
Murray–Darling
South-west Coast
6.1%
1.7%
South-east Coast
South Australian Gulf
10.6%
0.2%
Key
Timor Sea 23.3%
Water catchment area name Distribution of Australia’s run-off
Tasmania
0 250 500 km
13.3%
Source: MAPgraphics Pty Ltd Brisbane
The Ord River Scheme near Kununurra in Western Australia was designed to harness water that flowed into the Timor Sea. The Ord River dam can hold up to 5641 gigalitres of water, the equivalent of 11.2 Sydney Harbours. The water is used to irrigate crops, transforming land once only suitable for cattle ranches into economically viable land for crops. However, the scheme is controversial. Critics argue it is a waste of money and an environmental disaster. Others view the scheme as a potential bread basket for Western Australia, providing thousands of jobs and export earnings.
TOPIC13 Landforms and landscapes – diversity, significance and management 309
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