RANGE PRESERVATION AND EROSION CONTROL. 



13 



average rate of from 0.08 to 0.10 of an inch per hour, represent tin- 

 rapidity of rainfall characteristic of the storms thrQUghout the 

 son. As a rule, storms as mild as this have little effect in causing 

 rim-off or erosion. 



During the rainy reason of. 1916 conditions were somewhat dif- 

 ferent from those of 1915. There were several storms covering 

 periods of from two to five days successively. Naturally, storms 

 of such duration have a greater effect in causing run-off than short 

 mild storms. It was found that the rain for a time, depending upon 

 the prior condition of the soil as to dryness and compactness, was 

 absorbed and there was no surface run-off whatever ; but after the soil 

 became completely saturated and the rainfall still continued, run-off 

 occurred and with it was carried a large amount of sediment. (PL I, 

 fig. 1.) 



Table 1. — Rain f ah on erosion areas, season 1915. 



Date. 



Upper 

 gauge. 



Lower 

 gauge. 



Upper 

 gauge. 



Lower 

 gauge. 



June 1 . . 

 June 2 . . 

 June 3 . . 

 June 6 . . 

 June 9 . . 

 June 13 . 



July 4. . 

 July 21 ' 

 July 23. 

 July 24. 

 July 25. 

 July 26. 

 July 27. 



Aug. 5.. 

 Aug. 6.. 

 Aus;. 14. 

 Aug. 16. 

 Aug. 24 . 



Sept. 2.. 

 Sept. 3 . . 

 Sept. 4 . . 

 Sept. 7.. 

 Sept. 8.. 

 Sept. 11 . 

 Sept. 13. 

 Sept. 25 . 



Total , 



Total for the four months . 



Average. 



0.75 

 .25 

 .12 

 .95 

 .02 

 .03 



2.12 



.36 

 .70 

 .04 

 .10 

 .15 

 .07 

 .11 



0.75 

 .25 

 .12 

 .95 

 .02 

 .03 



2.12 



.34 

 .71 

 .04 

 .10 

 .13 

 .07 

 .11 



1.50 



0.75 

 .25 

 .12 

 .95 

 .02 

 .03 



2.12 



.43 



1.48 

 .04 

 .09 

 .12 

 .07 

 .11 



2.34 



.01 

 .09 

 .01 

 .14 

 .02 



.27 



0.75 

 .25 

 .12 

 .95 

 .02 

 .03 



2.12 



.40 

 1.38 

 .04 

 .10 

 .12 

 .07 

 .11 



2.22 



1 This was the only storm of the season to produce run-off. 



