Some Notes on the Hydraulics of Wells

In discussing the laws of flow into wells it is convenient to divide them into three classes: (1) wells in fissured rock, (2) ordinary wells, (3) artesian wells. Wells in fissured rock present such eccentricities that it is impossible to derive mathematical expressions of general application. Ordinary wells are those in a porous formation (usually sand or gravel) in which the surface of the water table is exposed to atmospheric pressure through the porous material above. Artesian wells are those in a water bearing stratum overlain by an impervious layer, and the water level in the well is at all times higher than the top of the water bearing stratum. Artesian wells may, or may not, be flowing wells under this definition. In Turneaure and Russell's "Public Water Supplies," the following formulas are derived for the yield of ordinary and of artesian wells: For ordinary wells