A NATIONAL PLAN FOR AMERICAN FORESTRY 381 



and lighter averages during autumn. Exceptionally heavy precipi- 

 tation has been experienced in many localities in the basin. Sudden 

 downpours of the " cloudburst" type have been recorded frequently 

 on the higher and mountainous portions of the basin. Concentrated 

 heavy rains covering most of the Ohio Basin have been experienced. 

 During the 4 days, March 23-27, 1913, storms brought from 1.4 to 

 11.1 inches of rain to various portions of this basin. 



WATERSHED PROBLEMS 

 FLOODS 



Floods are a recurring event for the population living in communities 

 along the major river and on portions of its tributaries. Speaking of 

 the Ohio River in 1913, Horton and Jackson 38 state than in no year 

 since 1873 has the Ohio River failed, at some point along its course, to 

 overflow its banks and flood large areas of adjoining bottom lands, in 

 some years flooding as many as five times. King 39 recites the dis- 

 asters on the Tennessee and Cumberland River Basins which have 

 come in 1924, 1926, 1927, 1928, and 1929, and shows that the Cum- 

 berland River at Nashville has been in flood 73 times since 1874, or 

 an average of more than once every year. 



The primary natural cause of floods in this basin is either concen- 

 trated and excessive rainfall over a period of a few hours time, as in 

 the floods of March- April 1907, and of 1913, or, in the northern part 

 of the basin, the unfortunate combination of frozen ground followed 

 by snowfall and warm rains, a condition which was responsible, accord- 

 ing to Horton and Jackson, for the 1884 flood. 



Among man-made causes, Horton and Jackson list the failure of 

 reservoirs, the breaking of levees, and the constricting of stream and 

 river channels by buildings, factories, abutments, grades, and the 

 like. A fundamental man-made cause of floods, not stressed by these 

 writers, but second only in importance to concentrated rainfall, is 

 deforestation and the disturbance or destruction of soil cover. 



The damages which can be charged against floods run into very 

 high totals. Horton and Jackson estimate the damage in the Ohio 

 Valley from the 1913 flood as more than $180,000,000. Of this, it is 

 estimated that Dayton, Ohio, received damage amounting to $100,- 

 000,000. Four hundred lives were reported lost. In the same 

 deluge, Columbus, Ohio, lost 3 bridges, more than 4,000 dwellings 

 were inundated, 20,000 people homeless, and 100 lives lost. A review 

 of damages as reported in the Monthly Weather Review indicates that 

 the annual losses from floods in the Ohio Valley have averaged about 

 $4,600,000 for the period 1920-32, exclusive of 1925 and 1931. In 

 Tennessee it is estimated that in the years 1926 to 1930 floods brought 

 losses of $20,000,000, or an average of $4,000,000 a year. The flood 

 of March 1929 destroyed more than 100 bridges in the Cumberland 

 Plateau region and middle Tennessee. King estimates conservatively 

 that floods yearly cost Tennessee $1,000,000. 



ss Horton, A. H., and Jackson, H. J. Flood of March-April 1913 The Ohio Valley. U.S.Qeol. 

 Survey Water Supply Paper 334, 1913. 

 39 King, W. R. Surface waters of Tennessee. Div. of Geol. Dept. of Educ. Bui. 40, 1931. 



