. Water Supply and Irrigation Papers of the United States Geological Survey . el by pumping from itat the rate of 20 gallons a minute,the same well may be expected toyield approximately 40 gallons aminute if the water is lowered 4feet below the natural level. Forshallow wells the yield will notincrease in this direct ratio, butwill be considerably less, on ac-count of the decrease in percola-ting surface, due to the loweringof the water table in the neigh-borhood of the well. Besides theadvantages just mentioned, tubu-lar wells, owing to their greaterdepth, are much more likely tostrike a vein
. Water Supply and Irrigation Papers of the United States Geological Survey . el by pumping from itat the rate of 20 gallons a minute,the same well may be expected toyield approximately 40 gallons aminute if the water is lowered 4feet below the natural level. Forshallow wells the yield will notincrease in this direct ratio, butwill be considerably less, on ac-count of the decrease in percola-ting surface, due to the loweringof the water table in the neigh-borhood of the well. Besides theadvantages just mentioned, tubu-lar wells, owing to their greaterdepth, are much more likely tostrike a vein of coarse material,a small stratum of which may beexpected to furnish much morewater than a considerable depth of fine material. This accountsfor the well-known superiority of deep tubular wells over commordug wells. When a large supply of water is required, as for irriga-tion or for village supply, if is a common practice to sink severatubular wells in the bottom of a large dug well (see fig. 32). In thisway not only is a large supply obtained, but the large well acts as. ]__ nmn p i- 1^ 14 i -|U[J[- yi .: .ILL V U U . 1 l mm 0- :y w Fig. 31.—Hoadleys laboratory apparatus forthe investigation of the phenomena of com-mon open and driven wells. « See the authors theoretical investigation of the motion of ground waters. Nineteenth AnnKept. U. S. Geol. Survey. Pt. II, 1899, pp. 358, 362, 364. BLIGHTER.] COMMON OPEN WELLS. 67 a storage reservoir, equalizing the load upon the pumps and permit-ting temporary overdrafts of the capacity of the wells. Some carefulmeaurements of the rate of rise of the water surface in a well afterpumping has ceased have been made by Mr. Willard I). from the city well at Garden, Kans., as obtained by him, areshown in figs. 33 and 34. The curve in fig. 34 agrees very closely with
Size: 1434px × 1743px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorunitedst, bookcentury1900, bookdecade1900, bookyear1902
