328 John Casper Branner 



The lowest stages of the river are usually during the latter 

 part of the summer and in the fall of the year. At such times 

 the water becomes nearly but not quite clear. This clearness is 

 due partly to a decrease in the volume and consequently in 

 the velocity and carrying power of the water, and also to the 

 large amount of common salt, lime, etc., in solution in the 

 water, which substances tend to flocculate and precipitate the 

 mechanical sediments. The greatest amount of mechanical 

 sediment found in the water during the 5^ear under consider- 

 ation was 225 grains to the gallon ; this was on the second of 

 May, 1888, when the river stood at seventeen feet on the gage, 

 and shortly after protracted rains over the whole or nearly all 

 the hydrographic basin of the Arkansas River above Little 

 Rock. It should be added, however, that while this high 

 water may be taken as a type of the ordinary rises, there are 

 times when there is but little or no rise, no increase in the 

 volume of water discharged, but a very marked increase 

 in the amount of mechanically suspended matter. In Octo- 

 ber, 1891, occurred one of these so-called " red rises " of the 

 Arkansas River, and although the river was quite low — mark- 

 ing only 3.9 feet on the gage — it carried out 761 grains of 

 matter to the gallon, of which only 48 grains was matter in 

 solution. Such a condition of the water is said to be due to 

 rainfalls on the Canadian River, an affluent of the Arkansas, 

 which runs through the " red beds " of western Indian Terri- 

 tory. This illustrates well the fact to which attention has al- 

 ready been called*^ that the sediments removed bear no con- 

 stant relation to the discharge. 



The total amount of suspended matter estimated by the 

 above methods to have been carried down by the Arkansas in 

 1887-8 was 21,471,578 tons. This estimate, however, must be 

 regarded as far short of the truth, for the method of taking 

 the water samples has left out of account that stream of al- 

 most liquid mud and sand that is pushed along the bed of the 



* Annual Report, Chief of Engineers, U. S. A., 1874, I, p. 863 ; 1S75, 

 I, p. 966 ; 1877, I, p. 433 ; Physics and Hydraulics of the Miss. River, 

 1876, p. 417. 



