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,orresponding values of t arc read from the graph values of t that are 22 times greater than the t The natural logarithm of the rano yo/yt is then values calculated by the t,o% equation in the taken and dnided by the difference bcmccn the original article (Bouwer and Rice, 1976), where 1 two valucs of t For example, Figure 3 shows that In(y./y,)was erroneously taken as In 0 9, thus at y is 0 28 m and 0 001 m, t is 0 and 24 seconds, yielding the time required for onl) 10% of the respectively This yields water-level rise or fall to occur 1/t In(yti/yt) = 1/24 In(0 28/0 001) = 0 23 m/sec If 1/t In(ytt/yt) is calculated from the slope of the COMPUTER PROGRAMS 1 curve, the number of log cycles on the vertical scale Where the Bouwer and Rice slug test is between the two points is divided by the time routinely used, time for calculating K with equa- increment and multiplied by 2 3 to convert to tion (3)is saved by de%eloping a computer program natural logarithm For example, Figure 3 short s in which valucs of 1.e/rw are stored for direct cal- that the straight line from yo = 0 28 m to culation of In(R,/rw )and K from the field data yt = 0 001 m covers 2 4 log cycles 7 he time Such programs have been developed by several 1 mcrement between the two points is again 24 users (see, for example, Pandit and Miner, 1986, seconds, yielding 1/t In(yo/yt)= 2 3 X 2 4/24 = 0 23 and Kemblowski and Klein, 1988) Also, a number m/sec, which is the same as calculated earlier of users have designed forms for easy and system- Because of different coordinate scales in plots of atic recording of field data log y versus t, the value of 1/t In(yo/yt) cannot be taken as the actual slope of the straight line REFERENCES portions Bouwer. H and R C Rice 1976 A slug test for determining hydraulic conductivit) of unconfined aquifers with ESTIMATING RATE OF RISE OR FALL OF completely or partially penetrating wells Water WATER LEVEL IN WELL Resources Research % 12, pp 423-428 If the %ater level in a slug tester) %ell rises or Kemblowski,M N' and C L Klein 2988 An automated numerical evaluation of slug test data Ground Water falls at a relatively slow rate, simple %k ater IC%CI v 26,pp 435-438 measuring deuces and a stop watch ma) be all that panda, N 5 and R F Miner 1986 Interpretation of slug is needed to do the test Fast-moving w ater levels, test data Ground Water v 24,pp 743-749 however, require the use of a pressure transducer and a fast-acting x-y plotter To get some idea 1 about the rate of water-level movement that can be expected to a slug-tested well and shat tyutliiitcnt ' to use, equation (3) can be solved for i Herman Rouuer receivrd R s and Al S degrees to 1949 and 1952 m Drainage Reclamation and Irrigation In(yo/yt) can be taken as In 10 to (.j is u' ., (yarn for National Agricultural Unrt�rrsrty at Nagenrngrn time to" required for rhe teaser 1: ,t � Ii�r Netherlands, ands Ph U degree in 1955 m Soeland rise or fall 90°� of the initial lottit 11aterAlanagernew from cornet/Unwersav New York lie i respective)), of the water It t t 1 ,i 1 1, was associated with the Agricultural 1 nginernng Uepari yields the equation mrnt of Auburn University Alabama front 1955 to 1959 before joining the U S stair►consrrvatron l aboraturyin Pboenn,, Arizona ubcrr be berantr Director to 1971 In toot',, = 1 15 rc 1n (6) 1970, be also was appointed Adjunct Professorat Arizona Khe rq State University in 7empr wt+rre he taugbt Ground 14ater Hydrology in for Grology and Civil I ngineenng Depart where K must be taken as the estimated or expected meats lip is also an Adjunct Nofessor at the University of value of K of the aquifer Equation (6)yields Arizona in Tucson l �l