558 



CONSERVATION 



at a time, under which condition, if 

 the writer understands Colonel Chitten- 

 den's theory and his admission, even 

 such a large stream would practically- 

 dry up. It would seem to be much more 

 reasonable to depend upon some means 

 of keeping up the springs and small 

 streams rather than upon the equal dis- 

 tribution of surface waters of the sum- 

 mer 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, 

 therefore, seems here inconsistent. In 

 discussing floods, he considers an ex- 

 treme condition in which the floods from 

 various tributaries arrive simultaneously 

 at a given point and from this he ar- 

 gues that forests increase the violence 

 of floods. In the case of extreme 

 droughts, however, he considers the 

 case — not where the low-water flow 

 from various tributaries arrive simul- 

 taneously 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 for- 

 ests upon snow melting. Colonel Chit- 

 tenden states that "it can be demon- 

 strated 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 reser- 

 voirs 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 satu- 

 rated, until a warm rain carries off the 

 whole mass of snow in a freshet. He 

 says, referring to the snow in the for- 

 est: "The water from the first melting 

 from the snow blanket does not sink 

 into the ground, but into the snow it- 

 self. 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 expe- 

 rience, 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 than the snow 

 in the forests below, because the top is 

 in a region of perpetual snow. Obvi- 

 ously, this is not the condition to be 

 considered in the present instance. But 

 Colonel Chittenden 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. Fre- 

 quently the 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 perco- 

 lating 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 pre- 

 vent 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 snow 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 re- 

 tain the snow ; but it is equally clear 

 that in the latter case the earlier spring 



