BYBEE-MALOTT : THE FLOOD OP 1913 



205 



PART III.— FLOOD QUESTIONS 

 Increase of Floods 



Are floods increasing, and if so, why? Leighton, in 'Water 

 Supply Papers No. 234/ answers the question with a very emphatic 

 affirmative. He bases his statements on the results of observa- 

 tions extended from 1875 to 1907, upon the Ohio River, the Alle- 

 gheny River, the Monongahela River, the Youghiogheny Ptiver, 

 the Wateree River, the Savannah River, the Alabama River, and 

 the Connecticut River. 



In the region studied, he gave the cause of floods and the cause 

 of the increase of floods as follows: 



1. Climate (including rainfall, evaporation, temperature, 



wind and humidity.) 



2. Topography. 



3. Geology. 



4. Vegetation. (Deforestation, growing crops, etc.) 



5. Artificial agencies (including breaking of dams, drain- 



age, etc.). 



He says, 'Summarily, therefore, it may be stated with confi- 

 dence that the increase of flood tendency is due by far the largest 

 measure to the denudation of the forest areas." 



It seems that, in Indiana, the deforestation of between 80 

 and 85 per cent of the total area of the State has had something 

 to do with the increase of flood frequency and flood height. This 

 is especially true of the southern part of the State, where the slopes 

 are more steep and the country more broken. According to F. 

 A. Miller and E. E. Davis ('Eighth Annual Report of the Indiana 

 State Board of Forestry,' 1908), the most noticeable change in the 

 activities of the Wabash River due to deforestation is the fact 

 that it rises and falls more rapidly now than formerly. In three 

 or four days it reaches a height that formerly took two or three 

 weeks; however, the fall of the flood crest is now sudden, as the rise. 

 Some seem to think that deforestation will cause the rainfall 

 to decrease, or, if not decrease, to be distributed more unevenly 

 through the year. This has not been satisfactorily proved. How- 

 ever, the following discussion will give the reader some idea as to 

 the nature of the work that is being done in trying to arrive at 

 some definite conclusion. Dr. Raphael Zon in Science (N. S. 

 Vol. XXXVIII. No. 968), shows that there is a close relationship 



