l8o CONTROL OF EROSION ON RANGE AND PASTURE 



(about one carload) of air-dry dirt and rocks of various sizes 

 (Fig. 56). 



Melting Snow. — The amount of erosion from melting snow 

 is considerable, especially where gully erosion is in progress. 

 The accumulation of winter snows on each of the two selected 

 areas described {A and B) has an average annual water equivalent 

 of about 9 inches.^ This accumulation represents approxi- 

 mately 326,000 cubic feet of water awaiting the spring thaw. 



Fig. s6. — erosion AREA A, HEAD OF EPHRAIM CANYON, MANTI NATIONAL 



FOREST, UTAH. 



As a result of the destruction of the plant cover, more than 50,000 pounds, or approximately one 



carload, of air-dry sediment was carried away from this lo-acre area by a single rainstorm. 



Now what becomes of this snow water? It was found that about 

 292,000 cubic feet, from a total of about 326,000 cubic feet, ran 

 off the steeper area (A) while about 42,000 cubic feet ran off 

 area B. A small amount of the snow water evaporates into the 

 air, but the greater portion of that which is not accounted for 

 in the surface run-off is absorbed by the soil. In the fall of the 

 year the gullies contain considerable loose dirt, practically all 

 of which is carried down by the snow water. That melting 



1 Sampson, Arthur W., and Weyl, Leon H., "Range Preservation and its Re- 

 lation to Erosion Control on Western Grazing Lands." U. S. Dept. of Agr. Bui. 

 67s. PP- 9-", 1918. 



