132 E. T. Quayle: Modifyivy Climate. 



increases in surface moisture. The clearing of the land, and the- 

 substitution of cultivation or pastures for the scrub forests on 

 the inland plains cause, according to the evidence, some im- 

 provement of the rainfall, especially during the spring months, 

 when the green growth results in vigorous evaporation. A more 

 general improvement results from irrigation, which ensures 

 growth of vegetation throughout the year. It is through this 

 means that the greatest effects are possible. The extension of 

 irrigation along the Murray between Echuca and Renmark, and- 

 in New South Wales, about the junction of the Darling with 

 the Murray, it is evident, will have a not inconsiderable effect 

 in ameliorating the climate of Northern Victoria, including the 

 Mallee. It should also increase the rainfall on the mountains 

 from which the irrigation water are derived. And if in con- 

 nection with these, large storages of water are made from the 

 lower Murray and Darling, say, by impounding flood waters in 

 banked-up lakes in the same way as those of the Goulburn are 

 impounded in the Waranga basin, the possibilities, if not almost 

 limitless, are at least very great. I see no reason why the im- 

 provement should not be equal to what would happen if an arm 

 of the sea like Spencer's Gulf, say, up to Menindie. It has al- 

 ready been shown that a reasonable result of this would be an 

 increased rainfall of from 3 to 5 inches in the neighbourhood, 

 even as far as 170 miles inland. 



If such a result could be brought about by increasing our 

 irrigated areas, and the necessary increase in the area of land 

 fully irrigated can surely be made, it would be hard to put any 

 limit upon the climatic benefits which Northern Victoria and the 

 Riverina would derive from it. Hann has shown that in New 

 South Wales a square mile of country carries 22 more sheep 

 per annum with a 12-inch than with an 11-inch rainfall, and 

 that the carrying capacity increases at a more rapid rate per inch 

 of rain as the rainfall increases, a 17-inch rainfall, for example, 

 enabling 70 more sheep per square mile to be carried than a 16- 

 inch one. 



Such an increase in our irrigated areas is likely, therefore, not 

 only to be worth while in its direct effects upon the country's 

 production, but by making further irrigation possible, to have 

 indirect effects of very appreciable magnitude. 



