FOKEST LANDS FOE THE PEOTECTION OF WATEESHEDS. 27 



the committee desires, can bring before you the evidence which shows 

 the results, and in the case of the Tennessee, which I have gone over 

 somewhat carefully, it seems to me it is a strictly scientific paper. 

 It seems to me that the information he furnishes shows conclusively 

 that in the past twelve years, as compared with the previous twelve 

 years, floods have been more frequent in proportion to the number of 

 flood-producing storms, and that is the point involved, by 18 per 

 cent or thereabouts. This is the one stream, it so happens, upon 

 which there has been a strictly scientific detailed study and analysis 

 of the facts. 



The CHAIRMAN. The theory, of course, is that the forest cover 

 constitutes a sort of sponge that absorbs the water, and in that way 

 prevents flood. 



Doctor VAN HISE. Yes. 



The CHAIRMAN. Is it not true that when this forest cover, this 

 sponge, becomes thoroughly saturated any excess water immediately 

 runs out? 



Doctor VAN HISE. No; even then the excess water will gather in 

 the needles and the leaves, and they will hold quite a lot of it. 



The CHAIRMAN. For instance, if I had a slate here instead of this 

 blotting paper, any water I dropped upon it would run off imme- 

 diately? 



Doctor VAN HISE. Yes. 



The CHAIRMAN. I take this blotting paper and drop water upon it 

 slowly, and no water runs off. I could continue that for quite a 

 while. But suppose, first, that I immerse the blotting paper and 

 saturate it thoroughly, then if I drop water on it would it not 

 run off? 



Doctor VAN HISE. It would run off slowly, and that is the great 

 point. The average run-off is the same. There is no claim by us 

 that there would not be the same average run-off if all the forest was 

 watered, but what I say is that instead of that being made homo- 

 geneous, so that this is a stream free from sediment, it will be a vast 

 torrent carrying down gravel and silt at flood time, and there will 

 be practically no stream at the other times of the year. So that this 

 flat surface is to equalize the flow, and so make it valuable for water 

 power more valuable for water power than for navigation, and so 

 forth. 



The CHAIRMAN. I realize that an ordinary rainfall would be ab- 

 sorbed by the humus and would be given out slowly later on, but 

 very flood comes from an excessive rainfall ? 



Doctor VAN HISE. Yes. 



The CHAIRMAN. Otherwise there would not be any flood. When 

 that condition occurs, when your humus is absolutely saturated, is it 

 not true that if the rain keeps on falling there will be a flood? And 

 is it not true that we have had floods in the rivers from time im- 

 memorial? Is it not true in Oregon and in Washington that some 

 of the severest floods that have ever occurred have come while the 

 forest cover was perfect? 



Doctor VAN HISE. It is entirely true that if the rain is so excessive, 

 if there is a flood-producing rain away beyond the capacity of the 

 forest to absorb it, that even with a virghT forest we still may have 

 a disastrous flood, although it will not be usually so ?ilt laden a flood 



