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OPERATIONAL DEFINITION FOR <br /> STEP DRAWDOWN TESTS, Page 2 <br /> Well efficiency is an integral function of well loss and aquifer loss , <br /> which are also determined with step drawdown tests. (The term loss <br /> refers to head loss, where head is the groundwater equivalent of fluid � <br /> potential ) . Well loss is the drawdown required to overcome the i <br /> resistance to turbulent flow in the vicinity of the well through the <br /> portion of the aquifer affected by well construction; through the <br /> well-aquifer contact (sandface) ; through the filterpack and screen; <br /> and within the well . Aquifer loss is the portion of the drawdown <br /> caused by resistance to laminar flow in the aquifer and through the <br /> portion of the aquifer affected by well construction. <br /> Several methods are available for interpreting step drawdown test <br /> data. Well efficiency can be determined directly with the step <br /> drawdown test data from the pumping well or through the use of <br /> observation wells. Similarly, several methods are available for <br /> determining a preliminary estimate of aquifer transmissivity. The <br /> reader is referred to the extensive literature on step drawdown tests <br /> and on well and aquifer testing, in general , for selection of a data <br /> analysis procedure. <br /> /S'OGF� A GROUNDi,, TEq CONSULTANCY <br />