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.i f e 152 GROUNDWATER HYDROLOGY GROUN 1 Hantush25,29 and others.37,39,65 Although evaluating the effects is ! canno complicated except for the simplest cases, common field situations ; invest s often reduce the practical importance of partial penetration.* One F sidera occurs where an observation well is located more than 1.5 to 2 times f Tak: the saturated aquifer thickness from a pumping well;in this situation may b the effect of partial penetration can be neglected for homogeneous and isotropic aquifers. Another applies to many alluvial aquifers with pronounced anisotropy. Here the vertical flow components become small, thereby enabling a pumping well to be approximated where as a fully penetrating well in a confined or leaky aquifer with a coedit: saturated thickness equal to the length of the well screen. Well Flow for Special Conditions A variety of solutions to well flow problems have been derived so that for special aquifer, pumping, and well conditions.23,38 Inasmuch as these are of less general application than those outlined heretofore and involve more extensive mathematical treatment, they will be heforf t omitted here. It is worth noting, however, that solutions have been the for: obtained for the following special conditions: Cons betwee 1. Constant well drawdown.2,23 can be 2. Varying, cyclic, and intermittent well discharges.22,41,46,58,63,64 3. Sloping aquifers.23 abler a srnaIl a� 4. Aquifers of variable thickness.23 5. Two-layered aquifers.26,32,51 6. Anisotropic aquifers.13,25.29.50.72 7. Aquifer conditions varying with depth;7.56 8. Large-diameter wells.52,73 9. Collector wells (see Chapter 5)28,45 10. Wells with multiple-sectioned well screens.$? Characteristic Well Losses The drawdown at a well includes not only that of the logarithmic drawdown curve at the well face,but also a well loss caused by flow - through the well screen and flow inside of the well to the pump -M intake.Because the well loss is associated with turbulent flow,it may be indicated as being proportional to an nth power of the discharge, as Q",where n is a constant greater than one.jacob34 suggested that a value n = 2 might be reasonably assumed,but Rorabaugh55 pointed out that n can deviate significantly from 2. An exact value for n *It should be noted that any well with 85 percent or more open or screened hole in the saturated thickness may be considered as fully penetrating.