WATER-POWERS OF ALABAMA. 



101 



Minimum monthly discharge of Cahaba River at Centerville, Ala., 

 with corresponding net horsepower per foot of fall on a water 

 wheel realizing 80 per cent, of the theoretical power. 



NOTE. To find the minimum net horse power available at a shcai 

 on this stream ,near this station, for any month, multiply the total 

 fall of the shoal by the "net H. P. per foot of fall" in this table for 

 that month. 



2. SURVEY OF CAHABA RIVER, ALABAMA. 



The Cahaba River rises near Birmingham, Alabama, and 

 flowing- in a southerly direction, enters the Alabama River at a 

 point just below Selma, Alabama. 



From the published notes of a survey made by the Corps of 

 Engineers, U. S. A., a profile has been made beginning at the 

 southwestern boundary of Shelby county, and running down the 

 river a distance of no miles to its mouth, in which distance 

 there is a fall of 227 feet. 



A United States Geological Survey hydrographic station has 

 been established at Centerville, Ala,, and measurements of dis- 

 charge have also been made at Sydenton, near Birmingham, but 

 the measurements and observations have not extended over a 

 sufficient length of time to give accurate estimates of discharge 

 at all seasons. The best that can be done at present is to form 

 an estimate of the river discharge for ordinary low stage of 

 water at Centerville, which is 344 second-feet, and add to or sub- 

 tract from this amount for other points on the river. From 

 measurements made on the same day at Centerville and at Har- 

 rell, near the mouth of the river, we estimate that the flow at 

 Centerville is about one-third of that at the mouth of the river. 



