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JOURNAL OF FORESTRY 



By the tentative formulae, then, the most probable flow of stream B 

 for the period was 1.754 ins. O. W. 



The actual discharge was 1.707 ins., or a deficit of 2.7 per cent. 



By deducting from the most probable for the whole year, the calcu- 

 lated amounts for the flood and summer periods, the result is entirely 

 different. The most probable discharge of B is then 1.523 ins. O. W. 

 and the actual of 1.706 indicates an excess of 12 per cent. 



It might be remarked in defense of the latter figure that calculations 

 by another set of formulae, showed the flow of B from August, 1919, 

 to January, 1920, to be steadily in excess of the most probable flow 

 under forest conditions. 



However, for the present, we are unable to make any positive state- 

 ment as to the effect of denudation in this least important period of 

 streamflow. 



5. Silt deposits in basins as a measure of erosion. 



The provisions for measuring the detritus carried by the streams 

 are entirely adequate so far as mineral soil is concerned, but in flood a 

 very appreciable quantity of organic silt may escape. 



Individual silt measurements in the period of comparison of the two 

 streams under forest, showed wide fluctuations, so that the calculated 

 ratio of B silt to A silt for any single period has only approximate 

 value. 



However, the results in this first year are so striking as to leave 

 little doubt. It should be remembered that they have been secured 

 without destruction of the humus by fire, and represent, in all proba- 

 bility, results of disturbance in logging the watershed. 



RECAPITULATION 



The calculations of streamflow for one year after denuding the 

 watershed known as "B," but before destroying the ground cover by 



