FORESTS AND FLOODS 35 



The power of the trees and forest soil to ab- 

 sorb water regulates the rate at which the rain- 

 fall is fed to the streams and rivers. Frequently 

 it takes weeks and even months for all the waters 

 of a certain rain to reach these streams. This 

 gradual supplying of water to the streams regu- 

 lates their flow. It prevents floods and freshets. 

 Careful observation and measurements have 

 shown that unforested regions will discharge 

 rain water at least twice as fast as will 

 forested districts. 



The stealing of soil by erosion occurs where 

 run-off waters are not obstructed by forest 

 growth. Silt, sand, and every other kind of soil 

 are swept from their natural positions and sprit- 

 ted away by the foaming waters as they surge 

 down the steep slopes. The stream or river 

 which is flooded by these rushing waters roars 

 down its narrow channel, tearing loose and under- 

 mining the jutting banks. In some cases, it will 

 break from its ordinary course to flood exposed 

 fields and to carry away more soil. As the speed 

 of the stream increases its power to steal soil and 

 carry it off is increased. Engineers report that 

 the carrying power of a stream is increased 64 

 times when its rate of flow is doubled. If the 



