246 



Water Conservation, Irrigation, and Drainage. 



By H. G. jMcKinney, ]\[. Inst. C.E., Chief Engineer for Water 

 Conservation. 



One of tlie most remarkable cliaracteristics of tlie continent of Aus- 

 tralia is the absence of liigli mountains and of great mountain chains. 

 Perpetual snows which elsewhere feed the rivers during- spring and 

 summer are almost unknown, so that Australian rivers, as a general 

 rule, are irregular in their flow, while in many cases they disappear 

 altogether in marshes or on sandy plains. These serious drawbacks 

 are felt throughout Australia, and constitute a formidable barrier to 

 the progress of settlement ; but their effect throughout a large portion 

 of New South Wales is slight in comparison with other parts of the 

 continent. The mouutaiii range which runs through this colony from 

 south to north, approximately parallel to the coast, and the summit of 

 which is roughly about 70 miles from the coast line on an average, is 

 the source of many important rivers flowing both east and west, and is 

 also the source of vast deposits of rich alluvium on the western plains 

 and of smaller though important and not less rich deposits in the 

 coastal districts. But the Dividing Range, as it is termed, is not the 

 only one which exercises great and far-reaching effects in connection 

 with the water supply of New South Wales. This range extends 

 northward through Queensland ; but near the southern boundary of 

 that colony, the range which forms the northern boundary of the 

 drainage area of the River Darling, strikes off in a uorth-Avesterly direc- 

 tion. As it passes westward, this watershed becomes less clearly 

 defined, and is in places represented merely by high rolling downs. 

 The area in Queensland south of this watershed is considerably over 

 100,000 square miles, so that New South Wales receives surplus water 

 and silt from that area beyond its northern boundary. In addition, it 

 is considered to be now practically proved that the source of the 

 splendid supplies of artesian water which have been found in southern 

 Queensland and in the northern and north-western districts of this 

 colony have their source in the watershed described. 



The Dividing Range varies generally from 2,000 to 5,000 feet in 

 height, but the Snowy Range, which is the name given to the most 

 elevated part of it, is seldom, if ever, without snow in some of its 

 ravines, and among its peaks includes Mount Kosciusko, the highest 

 mountain in Australia. The Snowy Range is the source of the River 

 Murray, while the Tumut River, the principal tributary of the Murrum- 

 bidgee, heads from the northern side of the same watershed. With 

 such a source as this it naturally follows that both the Murray 

 and Murrumbidgee have an abundant flow in the spring months, while 



