Mr. Chitten- 
den, 
472 DISCUSSION : FORESTS, RESERVOIRS, AND STREAM FLOW 
Proposition 2. 
“The above action fails altogether in periods of prolonged and 
heavy precipitation, which alone produce great general floods. At 
such times the forest bed becomes thoroughly saturated, and water 
falling upon it flows off as readily as from the bare soil. Moreover, 
the forest storage, not being under control, flows out in swollen streams, 
and may, and often does, bring the accumulated waters of a series of 
storms in one part of the water-shed upon those of another which may 
occur several days later; so that, not only does the forest at such times 
exert no restraining effect upon floods, but, by virtue of its uncon- 
trolled reservoir action, may actually intensify them.” 
The broad truth contained in this proposition—that floods have 
not increased with the settlement of the country—is accepted by all 
participating in this discussion. Engineering News, in its criticism 
of the paper, says: i 
“We believe that most engineers who give careful study to the 
question will find themselves forced to accept fully Colonel Chittenden’s 
most important conclusion given under (2) above, viz.: That forests 
do not prevent floods.” And again—‘With his main conclusion—that 
forests have little influence on stream flow compared with what is 
generally believed—we have already expressed our accord.” 
Conservation (formerly Forestry and Irrigation), the pages of 
which have always overflowed with the doctrine that forests do prevent, 
or at least diminish, floods, refers editorially* to “the well-known fact 
that flood heights do not sensibly increase with deforestation.” How 
many of the readers of this excellent magazine have ever gathered any 
such impression from its pages heretofore? And finally, Mr. Leighton 
says that “no well-informed person now believes that flood heights 
increase with deforestation.” The word “now” is significant. The 
statement itself may be correct; it certainly should be; but it is the 
very reverse of the teaching so vigorously put forth during the past 
two years in the interests of forestry.t And some “well-informed 
persons” apparently cling to the old theory still, if one may judge 
from the astounding statement by Dr. McGee in the December issue 
of Conservation, that “In a state of nature * * * most streams 
flow fairly clear and in fairly uniform volume throughout the year.” 
* November, 1908. 
+ Mr. Leighton, of course, will be willing that the writer should cite his testimon: 
before the Committee of Agriculture, January 380th, 1908, wherein he not only held that 
floods are now higher and of longer duration than they used to be, but explained why tbis 
must necessarily be so. His remarks are an excellent example of what one can prove if he 
only makes the right assumptions. Answermg a question by Mr. Hawley, Mr. Leighton 
said in part, comparing the past and present : 
“You cannot push through a channel more than a certain amount of water at a certain 
Stage. In the former conditions we will assume that half of the water was taken into the 
ground and half ran off directly. That half that ran off created a high fi 
same time it was of shorter duration because Lhe water was not there to continue ie "Now, 
ze will ray yaa ere lait _ em but < bas ‘ot ieee through the same channel, between 
© sam nks, erefore it cannot get throu 0 qui i 
te higher and at the same ime longer . ee gh so quickly, and therefore the flood will 
may be at Mr. Hawley was so unreasonabl ie 
the time of George Washington epread all over that ae pee ee 
