President's Address. 61 



the reservoir system exerting a very appreciable effect. The ten- 

 dency, however, would be in the right direction and we should 

 combine all methods which have the proper tendency, in order that 

 in the end we may have the greatest influence. 



FORESTS. 



During recent years much has been said regarding the influence 

 which deforesting and reforesting an area may have upon floods. 

 The great champion in the cause of cultivating forests to prevent 

 damage by floods is the honorable Government Forester. His en- 

 thusiasm has become contagious, and advocates of reforesting tree- 

 less areas as a means of flood prevention are numerous in all parts 

 of the United States. The subject is discussed here because in a 

 way it corresponds to the reservoir system. 



Rain falling upon a forested area is partially consumed in wet- 

 ting the leaves and branches of the trees, and to a perceptible de- 

 gree the water is held back and enters the drainage channel more 

 slowly, which in turn prevents a sudden rise of the stream. For 

 ordinary rains and mild floods there can be no doubt but that such 

 a covering of forest-trees materially reduces the stage of high water. 

 But here, as with reservoirs, it is the first rain that falls which wets 

 the leaves and branches and trunks of the trees. When excessive 

 rains come, four and five and six inches, the early rains thoroughly 

 wet and saturate all parts of the forest-trees — trunk, branch and leaf 

 — ^so that the latter part of the rain will have about the .same influence 

 on flood conditions as though the forests were not there. It seems 

 to the writer the importance of quantitative influence of forests has 

 been greatly exaggerated. Enthusiasts even go so far as to claim 

 that could we have our entire country reforested the whole problem 

 of flood preventions would be solved. Such parties should not be 

 called scientists, because the scientist sees in the river flood-plains, 

 as already explained, positive evidence that the river valleys of 

 America have been visited by floods in times past fully as much 

 and probably more than in modern times. This geological evidence 

 is not old simply because it is geological. It deals ^ith the most 

 recent period of geologic time, and links the past with the present. 

 It is little short of folly to teach that destructive floods can be pre- 

 vented by reforesting the surface of the country, no matter to what 

 extent such reforesting may be carried. 



In a measure, forests in a river flood-plain become positively 

 objectionable because they retard the flow of water already in the 

 stream. No sooner does a stream overflow its banks than the for- 

 est-trees interfere with the flow of water here, just the same as 



