PROCEEDINGS OF SECTION D. o3^ 



In point of fact, it has been shown that the great damage done 

 in parts of the eastern and central States has been directly due 

 to sudden and heavy floods in rivers whose soixrces were once 

 forested, but are now denuded of both tree and plant covering, 

 the latter arising from over-grazing on the cleared lands subse- 

 quently laid down with grass. It may be remarked in passing 

 that this latter evil is, no doubt, exercising bad effects on the 

 more recently settled lands of Australia. 



In one district in Utah, in which certain towns are situated 

 in steep-sided valleys, or canyons, denuded of forest and devoted 

 afterwards to pastoral purposes and then over-gi'azed, the floods 

 have been so violent, owing to quick torrential run-off, that drift- 

 wood, stones, and even boulders, have been carried into the streets. 

 As regards the fundamental principles connected with the run-off, 

 either slow or quick, from the head of a river with forest-cover, 

 it is generally admitted that the protection so afforded, coupled 

 with the influence of ground cover beneath the trees, retards the 

 run-off, and so equalizes the sti'eam-flow, except under the abnor- 

 mal conditions of complete saturation from phenomenally heavy 

 and persistent rain. Even then, the many obstructions caused 

 by leaves, branches, and roots above gi'ound, the channels of 

 rotten ones beneath the soil, decayed matter, and the stems of the 

 trees, all combine to cause a slower run-off, at the same time fur- 

 nishing a supply for existing springs, than is the case on open 

 ground, even after deducting the loss due to evaporation. The 

 removal of this forest and plant-cover destroys the water-holding 

 capacity of the soil and the greater evaporation ensuing after the 

 first heavy run-off which causes the flood, reduces the stream-flow 

 in times of drought to a minimum. 



In the foregoing remarks an effort has been made to give, in 

 short, the experience which has been gained in an old-settled coun- 

 try. It would be beyond the province of this report to deal fur- 

 ther with the immense damage that has been done to the soil 

 and lands in the United States from erosion and denudation by 

 floods. It has been the same in France and other European coun- 

 tries; as also in Japan, where the Government is undertaking a 

 scheme for the afforestation of bare land spreading over many 

 years. 



Your Committee thinks that conditions are more likely to be 

 disastrous in all Australian forests, except those of luxuriant 

 growth, than in the countries referred to, as the eucalyptus bush 

 in hiliy areas usually covers a soil more or less rocky and devoid 

 of humus owing t& the peculiar nature of the leaves and bark. 

 The soil is also usually shallow and less absorbent, except in the 

 valleys, and depends on the tree covering and that of a frequently 

 scanty undergrowth for protection, which, if removed and great; 



