FIRST RESULTS IN THE STREAMFLOW EXPERIMENT, 

 WAGON WHEEL GAP, COLORADO 



By Carlos G. Bates 

 Director Frccnwnt Bxpcriineni Station 



It is nearly ten years, since the first outline of the Wagon Wheel Gap 

 streamflow experiment, started jointly by the Weather Bureau and 

 Forest Service in 1910, was given to the Society. These ten years 

 have been years of suspense not only for me, but, I am sure, for 

 many other members of the profession, who have awaited. the results 

 of the first serious effort to obtain, under experimental conditions, a 

 Cjuantitative expression of forest influences on snow-melting, stream- 

 flow, and erosion. 



The period up to July 1, 1919, was devoted entirely to the refinement 

 of the technique, and the establishment of relations existing between 

 the two streams while hath were influenced by forest cover. For these 

 relations we have eight years' reliable records. Denudation of one 

 area (Watershed B) was begun in July, 1919, and completed by the 

 burning of most of the brush and debris in September, 1920. As the 

 ''streamflow year" begins October 1 and ends September 30, we now 

 have a record for one whole year, in which the forest has been almost 

 completely destroyed, but the absorbing capacity of the forest floor 

 has been little changed. While the results in this year may not be as 

 significant as those to follow, and the average results for several years 

 must be taken for the basis of any broad calculations, it is felt that 

 these first results will be extremely interesting, and therefore, with the 

 consent of the Weather Bureau, the following unbiased statement 

 is given. 



It should be remarked that each of the following calculations is made 

 according to formulae (expressed by diagrams) derived from the 

 eight years' record prior to denudation, and agreed upon by the two 

 Bureaus as showing the most probable relation of the two streams 

 under forest influences, for various climatic conditions. These for- 

 mulae are not perfect, and improvement in them may be made as tim.e 

 goes on. As at present accepted, they will shortly be published in the 

 Monthly ^^^eather Review. 

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