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Hydraulic conductivity is defined as the rate at which water <br /> moves through a porous media (soil) under a unit hydraulic <br /> gradient, It is primarily dependent upon the porosity and <br /> permeability of the soil and the density and viscosity of the <br /> water. However, not all water occupying pore spaces in a <br /> saturated aquifer can be readily extracted. One measure of <br /> the water-yielding ability of an aquifer is the storage <br /> _ coefficient. The storage coefficient of an aquifer is <br /> defined as the volwue of water produced per unit horizontal <br /> area by a unit drop in the water table level (unconfined <br /> aquifers) or the piezometric surface (confined aquifers) . <br /> Another term indicative of the water yielding capacity of an <br /> aquifer is its transmissivity or transmissibility. The <br /> transmissivity of an aquifer is the product of the hydraulic <br /> conductivity and the saturated thickness {B) , or <br /> T KB <br /> Of ir.tereat in understanding aquifer characteristics is the <br /> movement or yielding capabilities of the wat.ar-bearing <br /> formation. It is necessary to obtain values for one or more <br /> of the aquifer properties to determine these parameters. <br /> Various techniques have been developed for obtaining values <br /> for these properties or parameters. <br /> The pump test technique is generally used to evaluate the <br /> hydraulic properties of aquifers. The results of this test <br /> are used for predicting well yields, position of water tables <br /> and piezometric surfaces, and recharge rates of aquifers. <br /> p Other techniques, such as the auger-hole and slug test <br /> s <br /> {rate-of-rise techniques),hniques), have been developed to <br /> measure the hydraulic gradient {R) of the soil profile in <br /> shallow ground water. <br /> 4.1.1 pumped-Well Technique <br /> With the pumped-well technique, often called pumping test, <br /> hydraulic properties of the aquifer are determined by <br /> pumping a well at a constant rate and observing the <br /> in <br /> drawdown of the piezometric surfaces or water tab <br /> observation wells at some distance from the pumped <br /> well. <br /> e <br /> Two types of tests are used: steady-state and nonsteady or <br /> transient-state test. With the steady-state test, pumping <br /> is conducted for a sufficient period of time for the water <br /> levels in the observation wells to approach equilibrium. <br /> The equilibrium drawdown then enables the calculation of <br /> transmissivity {T) . With the transient pumping tests, the <br /> change in water level in the observation wells is measured <br /> in relation to time, to determine the properties T and S. <br /> ° i <br /> h <br /> S <br />