492 CONSERVATION 



not rest upon an impervious surface, and it can simply hinder the discharge 



The forest and its cover prevent the of later rain-water by physically ob- 



earth beneath from being baked by the structing its flow. 



sun and compacted by the rain. It is The general aspect of this part of the 



kept in a porous condition ready to ab- subject seems, after all, quite simple, 



sorb water which filters down to it The forest floor absorbs a large amount 



through the forest cover. Any conclu- of water, prevents it from flowing off 



sion, therefore, drawn from Colonel rapidly, and allows it to gradually per- 



Chittenden's simile must be inaccurate, colate into the porous ground beneath. 



The author's summary of this part of If the land were clear of vegetation, or 

 the discussion is perhaps contained in if it were cultivated, and especially if 

 the following sentence : "That the for- the slopes were steep, the erosion would 

 est does promote tributary combina- be greater, and might sooner or later 

 tions, there would seem to be no ques- leave no soil upon the rocks to serve 

 tion, and that it may therefore aggra- as a reservoir in future storms. The 

 vate flood conditions necessarily follows, author's argument, therefore, leaves un- 

 it is not contended that this increase assailed the beneficial effects of forests 

 is ever very great, but it is contended in regulating flow. 

 that forests never diminish great Hoods The fact must be emphasized that 

 and that they probably do increase them those who believe in the beneficial effect 

 soinezvhat." of forests upon flow do not urge the 



It would seem to be much nearer the preservation of the forests on lands 



truth to say that forests generally di- needed for agriculture. The beneficial 



minish floods, although it is conceivable effects of the forests on flat lands in 



that a forest may slightly increase a modifying the violence of freshets and 



given flood at some points. increasing the low-water flow is much 



The author further states that "the less clear than in the case of forests in 



forests are virtually automatic reser- steep mountain regions. It is the pres- 



voirs, not subject to intelligent control, ervation of these last forests upon 



and act just as the system of reservoirs land not suited to agriculture that is 



once proposed by the French govern- believed to be especially important from 



ment for the control of the floods of every point of view, 

 the River Rhone would have acted if The statement of Colonel Chittenden 



built. These reservoirs were to have that the flood of 1908 in the Western 



open outlets, not capable of being States would have been much greater if 



closed, which were intended to restrain the region had been forested, is a mere 



only a portion of the flow. A careful statement of his own opinion, entirely 



study of their operation in certain re- without proof, and undoubtedly inca- 



corded floods showed that they would pable of proof ; and. further, if the 



actually have produced conditions more gauge records given by him show that 



dangerous than would have occurred it is impossible to find evidence in them 



without them." to support the current theory of forest 



The last sentence of this quotations is influence, it may also be stated that 



rather conjectural and its meaning is there is nothing in them to support his 



not quite clear, but it will be surpris- own contention. 



ing to most people to be told that a res- The question will, of course, have 

 ervoir not subject to intelligent control occurred to the reader of these re- 

 does not regulate, and they will hardly marks : Why it is not possible by long- 

 accept the statement. Of course, a lake continued observations of the height of 

 is a more efficient regulator than a for- floods on our rivers to settle this ques- 

 est, because, if its level is rising, the tion absolutely? With reference to this 

 discharge from its lower end is always some explanation is necessary. The 

 less than the flow into its upper end, flow of a stream is the resultant of a 

 while in case of the forest, when its number of elements, chief among which 

 storage is exceeded, its level cannot rise, are rainfall, its distribution throughout 



