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mcawrcd If the water Ic%c1 rises in the scrccncd or
<br /> 2 re open section of the %cll w ith a gra%el pack around
<br /> t it, the thickness and porosity of the gra%el cntclopt
<br /> - WATER TABLE should be taken Into account K hen calculating the
<br /> Y equnalent value of rc for the rising water le%el
<br /> Ihis calculation is based on the total free-water
<br /> surface arta in the well and sand or gravel pack,
<br /> calculated as rrrc + X(rq? - rc=)n, %here n is the
<br /> porosm , and r„ - rc is the thickness of the
<br /> LW (mclopc The equi%alcnt radius of a circle gi%Ing
<br /> this total arca is t en calculated as
<br /> H 10 - n)rc' + nr,,'] ' For example, if the radius of
<br /> 2rw - L thk screen or perforated casing is 20 cm and there
<br /> t I e is 8 cm gra%el pack with a porosity of 30 percent,
<br /> I rc should be taken as 25 9 cm while ry Is 28 cm
<br /> 5ohing equation (2) for Q, equating t c
<br /> resulting expression to equation (I), integrating.
<br /> and sol%mg for h yield%
<br /> K = rf In(K,/r,,) I In )o
<br /> (3)
<br /> 21,t t Y,
<br /> %hcrc y o = } at time icro,and = ) at time t
<br /> I he results of the analog anal%scs to a%aluatc
<br /> R, for %anous s)stem gromctrics a crc expressed
<br /> in terms of the- dimensionless rano In(K,/ria) I ht
<br /> IMPERMEABLE data could be fitted Into two equations, one for
<br /> Fro t Geometry and symbols for slug test on partially tht carr %here L. < }l, and one ahcrc " = II
<br /> penetrating, partially screened well in unconfined aquifer the resulting equations%crc, respcctl%ci),
<br /> with gravel pack and/or developed zone around screen
<br /> In
<br /> rW IIn(1.µ/r„) Lc/ria J
<br /> %ell,R = effectne radial distance mtr %%1-t t, ,
<br /> c
<br /> dissipated,and r,, = radial distint t cif und-i I ,: K, I 1 C i
<br /> portion of aquifer from ccntcrlim it�1 In r%% T In(L.%, /rA + i.k/r„ (5)
<br /> Values of Kc m ere dcttrnimid v �
<br /> electrical resistance nctaork aiialo� �'t kill %%hcrc A, $, and C arc dimensionless numbers
<br /> values of r,� , Lr, L,� , and 11 (%c c I Feu.k 1 for nican plutttd in I igurt 2 as a function of Lk/r„
<br /> Ing of geomctr) symbols) the %alut of r„ i% the
<br /> radius of the scrccncd or open sec tion of the %ell
<br /> plus the thickness of a sand or gra%cI pact, and/or "� ,--- � T ,-� -*---T-�� t-^-•---�
<br /> of the developed ione around the acll Thus, rM is C'--
<br /> the radial distance from the center of the %ell to w�`2i •'
<br /> normal K of the aquifer Htcausc the thichnes%of ` .o' i
<br /> the developed zone is almost never knom n, the `
<br /> tendency is to ignore it and talc only gra%cl or ' e
<br /> sand packs into account
<br /> The f ` '
<br /> talc a rise dy/dt of the aatcr le%�rl in the � �• i
<br /> well after the water level has been quickly lowered :
<br /> some distance Is
<br /> dy Q -
<br /> _ (2) Ot ate b' #,4..sra.i.r
<br /> dt trr� s w W roo $oo ow soon
<br /> y'#'r
<br /> Where rc is the radius of the- casing or other section Fig 2 Dimensionless parameters A,8, and C as a function
<br /> of the %%'01 Khcrc the rise of the aatcr Irk cl is of 1_flr.. for calculation of InfR.h,,,l = 02,4'
<br />
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