Analysis and Evaluation of Pumping Test Data (2nd ed.), Publication 47, Intern. Notes on determining permeability by pumping tests under water-table conditions, U.S. A generalized graphical method for evaluating formation constants and summarizing well field history, Am. The estimated aquifer properties are as follows:Ĭooper, H.H. observation well measurements (time and displacement)ĪQTESOLV provides visual and automatic methods for matching the Cooper and Jacob modified nonequilibrium method for unconfined aquifers to pumping test data.The Cooper and Jacob (1946) solution may be used for the interpretation of pumping tests in unconfined aquifers through the application of the following simple correction to drawdown data measured during a test ( Kruseman and de Ridder 1994): s ′ = s - s 2 / 2 b (1)įor more information regarding this method or to apply the solution without the dewatering correction, refer to the Cooper and Jacob (1946) solution for confined aquifers. drawdown is small relative to saturated thickness of aquifer The Neuman (1974) equations for unsteady flow to a partially penetrating well in an unconfined aquifer with delayed gravity response are as follows: s Q 4 T &Integral 0 4 y J 0 y u 0 y + &Sum n 1 u n y d y (1) r 2 K z b 2 K r (2) S S y (3) t s T t S r 2 (4) s D 4 T Q s (5) Drawdown in a piezometer is found.flow is horizontal and uniform in a vertical section through the axis of the well.low velocity is proportional to tangent of the hydraulic gradient instead of the sine (which is actually the case).values of u are small (i.e., r is small and t is large).For an unconfined aquifer the well discharge can be expressed as an. diameter of pumping well is very small so that storage in the permeability, the shape of the drawdown curve, and the thickness of the aquifer.water is released instantaneously from storage with decline of hydraulic head.aquifer is homogeneous, isotropic and of uniform thickness.Jacob's correction applies to pumping tests with discharging wells and is not appropriate for injection tests. Jacob is credited with a procedure (Jacob 1944) that corrects drawdown data for the reduction in an unconfined aquifer's saturated thickness resulting from groundwater withdrawal by a pumping well and thereby enables pumping tests in water-table aquifers to be interpreted by methods for nonleaky confined aquifers such as the Cooper and Jacob (1946) solution.

Well drawdown unconfined aquifer