With large areas of fertile land lying waste for want of water, and water in abundance in the rivers, we should expect that attempts would be made to bring the two together. In New South Wales, near Yass on the Murrumbidgee, a great scheme is in progress. The Barren Jack dam, when finished next year, will hold up and make available for agriculture, a mass of water comparable to that of the Nile at Assuan. It will preserve, for the dry season, the water from the winter rains and the melting snows of spring. Other schemes are proposed for the Lachlan and Murray; up to the present, however, the chief development of irrigation has been in Victoria, on the streams flowing into the Murray and on the main river itself. Here we see the process of impounding 30 the water; notice the woods in the background which show that we are on the upper course of the stream, near the hills and the region of heavier rainfall. Here again is a great reservoir being 31 excavated, to hold the flood water; and next we may see the water flowing out into the irrigation channel. In another place the 32 water is being pumped up into high-level tanks for distribution. 33 The river has gradually built up a flood plain at a higher level than its usual channel; so that the water must be raised before it will flow over the fields. At Mildura and Renmark, the latter in South Australia, a large fruit-growing industry has been developed on the basis of irrigation. So we find lemons and apricots, and above all the currant and the vine which give us our dried currants and raisins.
But the supply of water in the rivers is limited, for the rivers are not broad or deep, in spite of their great length. One of the chief difficulties of all irrigation schemes is to avoid damage to the interests of people living lower down the stream, or interference with the navigation. In this matter the interests of all three States of the Commonwealth must be considered, since the Murray basin is divided among them. As we have already noticed in the case of Queensland and New South Wales, the State boundaries only coincide in part with natural features of the country.
The whole character of the river basin depends on the distribution of the rainfall. In the case of all three States there is a similar arrangement: first the coast belt, which is more varied and irregular in Queensland and Victoria than in New South Wales; then the highland edge, and then the back slope with a zone of moderate rainfall which shades off gradually into desert conditions. This zone narrows as we come southwards until it almost disappears in South Australia. But before following it out into this last State we will cross Bass Strait to visit Tasmania. Victoria, though a mere corner of the Australian continent, is about the size of Great Britain, while Tasmania is not very much smaller than Ireland, and both could support a very dense population. We must bear these facts in mind during our rapid journey through the country, since the maps in our atlases, for the most part, give us utterly wrong impressions as to the area of Australia.