Despite the vast size of Australia it has relatively few major river systems. The reason for this is quite simple as over 70% of the country is made up of arid and semi-arid land. The major catchment area of the continent is made up by the Murray River. The river runs for a total of 2,500 kilometers from its source in the Australian Alps to where it empties into the Southern Ocean at Lake Alexandrina. The combined Murray-Darling river system covers an area of virtually one seventh of the county’s total land mass and the nations next 4 largest rivers are tributaries into this system. None of Australia’s major cities border the river, with the largest settlement located on the banks being Albury, New South Wales with a population of 48,000 people. The rivers catchment area is noted as being the bread basket of the Nation.
The rich soils provided by the flood plains have enabled Australia’s agricultural community to successfully farm the land. The river has been used for irrigation since the 1850s and this has led to problems with the rivers discharge. In times of low rainfall the river bed has been known to dry up. The largest natural sea port in the world is Sydney Harbor which is a drowned valley estuary which is known as a Ria. The River Parramatta is the river that flows into the estuary and it only flows for 14 kilometers from its headwaters where the Darling Mills Creek and the Toongabbie Creek meet. On the far western side of the country the River Swan runs through the centre of Perth into the Indian Ocean at Freemantle. The mouth of the river starts 175 kilometers upstream in the Darling Range where it is called the River Avon.
The river has catchment area of 100,000 square kilometers and in the past has been prone to flooding. While this has been useful in maintain the fertility of the agricultural soils it has needed to be controlled as man has settled on the surrounding lands. Nearby New Zealand does not have the land mass that Australia has but a more temperate climate means that the country is more intensively drained. The country is divided between the North and the South Islands, and this is how the drainage areas have been divided up.
The longest river in the country is the Waikato which flows for 425 miles on North Island, from its source on the slopes of Mount Ruapehu to its mouth where it empties in to the Tasman Sea, just south of Auckland. The river is a spiritual waterway for the local Maori tribes who see it as the source of their pride. One of its main sources is from the Mangatoetoenui glaciers and a lot of its course is along glaciated areas. This can result in the falling water levels during cold periods exposing small islands within the main channel.
The South Island is dominated by the Clutha River/ Mata-Au which flows for 338 kilometers from Lake Wanaka in the Southern Alps to Pacific Ocean to the south of Dunedin. The river is a fast flowing body of water and has the highest volume of any river in the country. The discovery of gold in the region in 1861 resulted in a gold rush that saw the arrival of 18,000 miners by 1864. The fast flowing waters are ideal for hydro-electricity and there are two stations at the Clyde Dam and the Roxburgh Dam, which provide electricity to New Zealand’s central grid system. The rivers found in New Zealand reflect the country’s topography and climatic conditions. They are not the largest in the world but they are a source of great energy.