22 GENERAL INTRODUCTION 



POWER FROM INLAND WATERWAYS 



There are great possibilities of hydro-electric power develop- 

 ments in connection with inland waterways, and this subject 

 should be given careful consideration when improvements or 

 new projects are contemplated. The advantages to communi- 

 ties through the development of such water powers would be, 

 besides the benefit of cheap electric power, the prevention of floods 

 and increased efficiency of river navigation. 



The low water in many rivers during the dry season would 

 absolutely prevent navigation unless dams with locks were 

 provided for raising the water level, while on the other hand 

 there are a very large number of streams that are not now navi- 

 gable at all, but which could easily J^e converted into streams of 

 great commercial value. 



When a dam is to be built for improving the navigation of a 

 river, consideration should, therefore, always be given to the fact 

 that every dam not used for the development of electrical energy 

 means just so much loss of income. Such dams should, therefore, 

 be built of adequate height for possible hydro-electric develop- 

 ment. 



The prevention of floods is also of the utmost importance. 

 In the United States alone the yearly flood loss has for a number 

 of years exceeded several hundred million dollars. 



Storage and levee systems appear to be the only practical 

 solution for flood prevention. Storage of flood waters is effected 

 by forests and similar surface vegetation and by artificial reser- 

 voirs. The amount stored by forests is and probably will be for 

 a long time to come indeterminate, since the forest is merely an 

 agent in assisting the ground to absorb the water. This is, there- 

 fore, essentially a ground storage, and the ability of the forest to 

 enhance this is dependent absolutely on the soil beneath the forest. 



The extent to which flood waters could be stored by reservoirs 

 depends on the available reservoir capacity in the several river 

 basins. As a rule, the more diversified the character of the 

 basins, especially in contour, the greater facilities they afford for 

 reservoir storage. Large portions of many rivers are not subject 

 to correction by reservoirs, as in the Mississippi Valley for example. 

 It is, therefore, probable that streams draining one-third of the 

 area of the United States must forever be subject to floods, and the 



