File:Geology and underground water resources of northern Louisiana (1906) (14783055813).jpg

Identifier: geologyundergrou00veat (find matches)
Title: Geology and underground water resources of northern Louisiana
Year: 1906 (1900s)
Authors: Veatch, Arthur C. (from old catalog)
Subjects:
Publisher: (n. p.)
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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Text Appearing Before Image:
Fig. 29.—Experimental illustration of lo^s of head by resistance and leakage.(Alter David, 1893.) regions. The extent and cause of this variation is indicated bythe character of the factors in the following equation: Pressure head at a given point in any stratum, expressed in feet above sea level = elevation of ground-water table at source— loss by resistance—loss by leakage. All the members on the right-hand side of this equation areirregular variables. The first, the elevation of the ground-watertable at the outcrop or source, depends on the elevation of thesurface, which changes at different points. The seconddepends on the size of the spaces between the grains, whichin even the most uniform beds is a constantly changingquantity and in beds such as those of the lyower Eocene isextremely variable. The third varies with any change in the 322 i
Text Appearing After Image:
veatchI Underground Water of Northern L,a. 75 coarseness of the adjacent beds, which are never constant, and isaffected by faults, joints, and other natural breaks. This variation may be artificially shown in the manner indi-cated in fig. 29. In this experiment a tube is filled with sand,coarse shot, and marbles, representing beds of different coarse-ness, and the lower end of the tube is closed with a brick to pre-vent the materials from running out. When water is allowed toflow in from above, it rises to different heights in the small tubes,representing wells.

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