108 FOEEST LANDS FOE THE PEOTECTION OF WATEESHEDS. 



It would seem to be much more reasonable to depend upon some means of keep- 

 ing up the springs and small streams rather than upon the equal distribution 

 of surface waters of the summer showers from deforested areas. 



Moreover, it is not evident why, even in a small stream, a uniform flow is 

 any less desirable than an intermittent flow. Of course, as is well known, the 

 larger the stream the greater the low-water flow per square mile, other things 

 being equal, for the very reason that the low-water flow on all tributaries will 

 not occur at the same time, no doubt partly owing to local rains. A precisely 

 similar remark applies to the flood discharge, which is less per square mile on 

 large watersheds than on small ones, because the maximum discharge from 

 different tributaries will not occur at the same time. Colonel Chittenden, there- 

 fore, seems here inconsistent. In discussing floods he considers an extreme 

 condition in which the floods from various tributaries arrive simultaneously at 

 a given point, and from this he argues that forests increase the violence of 

 floods. In the case of extreme drouths, however, he considers the cas"e, not 

 where the low-water flow from various tributaries arrive simultaneously at a 

 given point, but, on the contrary, where comparatively high water from one 

 arrives at the same time as the low water from another. 



With reference to the effect of forests upon snow melting, Colonel Chittenden 

 states that " it can be demonstrated that the effect of forests upon the run-off 

 from snow is inevitably to increase its intensity.'' 



He argues that the snow does not drift at all in the forests, but that great 

 drifts form on open ground ; that the snow begins to melt over open ground 

 earlier than in the forests, and that the drifts on open ground serve as reservoirs 

 to feed the streams, lasting much longer than the snow in the forests ; that the 

 snow melting* in the forests does not sink into the ground, but into the snow 

 itself, which becomes saturated, until a warm rain carries off the whole mass 

 of snow hi a freshet. He says, referring to the snow in the forest : " The water 

 from the first melting from the snow blanket does not sink into the ground, but 

 into the snow itself. Snow is like a sponge; a panful will shrink to one-fourth 

 of its volume or less before any free water appears." 



This argument contains a number of errors and inconsistencies. In the first 

 place, the snow does drift in the forest, although not to the same extent as in 

 the open. Colonel Chittenden admits that the snow blanket lasts longer in the 

 forests than in the open, except for the drifts. It is the present writer's experi- 

 ence, however, that the snow in the forests lasts considerably longer than even 

 the drifts in the open, although this may not be true in the case of very high 

 altitudes. The snow in the drifts on or near the summit of Mount Blanc, of 

 course, lasts longer th;m the snow in the forests below, because the top is in a 

 region of perpetual snow. Obviously this is not the condition to be considered 

 in the present instance. But Colonel Chitteuden ignores the fact that under 

 the snow the ground in the forest is warmer than the ground in the open and 

 that the snow blanket melts at the bottom rather than at the top. Frequently 

 th3, ground in the forest does not freeze at all and therefore it is in a better 

 condition to absorb the melted snow than the ground in the open. But even if 

 the snow blanket in the woods absorbs, as he thinks, the water from its own 

 melting under the sun's rays, preventing it from percolating into the ground, 

 why do not the large drifts in. the open, which he says form the main reservoirs 

 of the streams, also absorb their own water and prevent it from running off? 



The fallacy of Colonel Chittenden's arguments in this respect is obvious. 

 It is, of course, true that if a warm rain comes upon the suow blanket in the 

 woods, carrying it off in a short time, the resulting flood may be greater than if 

 the forest had not been there to retain the snow ; but it is equally clear that in 

 the latter case the earlier spring floods would have been increased. If a given 

 .imount of snow has to be carried off into the streams, it is obvious that the 

 flow of the streams will be more regular if the period of melting is extended, 

 and this is the effect of the forests. 



A further instance of illogical reasoning is found in Colonel Chittenden's 

 reference to the great floods which occurred in the State of Washington. He 

 says : " The great flood of 1900 in this section was a perfect demonstration not 

 only of -the vast intensifying effects of forests upon floods due to snow melting, 

 but of the utter helplessness of the forest bed, when saturated with long rains, 

 to restrain floods." It will be clear, however, upon reflection, that this flood is 

 no demonstration of any " intensifying effect." It simply demonstrates that 

 there may be heavy floods from forested areas. If those forests were cut down, 

 That same flood might, and probably would, have been much more violent. 

 Colonel Chitteuden here apparently forgets the difficulties in studying this 



