11.2 OUTLINES OF FORESTRY. 



the river to safely discharge the waters of even a 

 very heavy rainfall. 



If, however, the character of the surface is such 

 that the larger part of the rainfall runs directly off 

 the slopes into the river channel, then an inunda- 

 tion must necessarily attend every heavy rainfall. 



If the greater part of the rainfall runs directly 

 off the surface into the river channel, and a com- 

 paratively small part goes to feed the reservoirs of 

 the springs, and if a long time elapses hefore the 

 next rainfall, the springs will dry up, and the 

 water in the river will get very low. 



Any disturbance in the natural drainage of a 

 country may cause a damage of two different 

 kinds: 



1. The damage due to the overflowing of the 

 rivers, or that directly due to too much water. 



2. The damage due to the drying up, or the 

 getting too low, of the rivers in the intervals be- 

 tween the storms, or that due to too little water. 



The proportion of the rainfall that sinks quietly 

 into the earth, as compared with that which flows 

 directly off its surface, depends on the character 

 of the surface. As a rule, a surface devoid of 

 vegetable covering that is, a surface on which 

 no vegetation is growing will permit a larger 



