Lab 5. Aquifer Pumping Testing - Theis and Jacob
Methods
Purpose: Learn the Theis and Jacob (graphic) methods of determining hydrologic
properties - transmissivity and storativity from pumping test (drawdown)
data.
Reading Assignment (Reviews of graphic methods of Theis and Jacob solutions)
Fetter p. 197-203; p. 219-227.
Lee and Fetter, p. 61-65.
Materials: 3 x 3 cycles log-log paper (for Theis analysis) and 3 x 10 semi-logarithmic
paper (for Jacob method) will be provided by instructor.
Problem 1: Analysis of aquifer test data by Theis and Jacob methods.
Work on problem 1 on p.66 of Lee and Fetter. Answer questions (a), (b),
(c), (d), and (e).
(1) Theis method:
The Theis type curve is shown in the next page (notice that The time unit
is day). Superimpose your data plot (s vs. t plot; since it is a one well
problem) to match the Theis type curve (keep the coordinates parallel).
Select a matching point gives m = 1 and , W(m) = 1, then read s and t in
your data plot.
Insert s and t values in the following equations to calculate transmissivity
(T) and storativity (S). Express T in ft2/day (1 gal = 0.134 ft3; 1 day
= 1440 min); S should be dimensionless.
T = _F(Q, 4ps) W(m)
S = _F(4Tmt, r2)
Where pumping rate Q = 220 gpm (gal/min) and r = 824 feet for a observation
well location.
(2) Jacob method:
Plot s vs. log t in the semi-log graph, determine t0 and Ds (see instruction
on Page 64). Use the the following equations to calculate transmissivity
(T) and storativity (S):
T = _F(2.3 Q, 4pDs)
S = _F(2.25 T t0 , r2)
Problem 2: Analysis of slug test data by Cooper-Bredehoeft-Papadopulous
Method
Calculate the H/H0 ratios from data collected in our field slug test at
the Auburn Fisheries Station. Plot H/H0 as a function of time on semilogarithmic
paper. Superimpose your data plot (H/H0 vs. t plot) to match the type curve
(keep the coordinates parallel). Does you drawdown data curve follow closely
with any type curves? If not, what may cause the deviation (check Fig 7.4
of Fetter). The data are matched (do your best) to the type curve (m), which
has the same curvature. What is the m value? Select a matching point for
Tt/r2 = 1. At the axis for Tt/r2 = 1.0, read the value for t1. Use the following
equations to calculate transmissivity (T:ft2/sec) and storativity (S):
T= _F(1.0rc2, t1)
S= _F(mrc2,rs2)
where rc = 0.33 feet (radius of well casing), rs = 0.33 feet (radius of
well screen).
(here is one data set, use your own data, if possible)
Time (sec) H(above initial water level, feet) H/H0
0 2.19 1
5 1.25 .57
10 1.02 .46
15 0.88 .40
20 0.75 .34
25 0.65 .30
30 0.59 .27
40 0.49 .22
50 0.42 .19
60 0.37 .17
70 0.33 .15
80 0.31 .14
90 0.28 .13
100 0.26 .12
110 0.25 .11
120 0.23 .10
140 0.21 .09
170 0.18 .08
210 0.15 .07
240 0.13 .06
270 0.12 .05
360 0.09 .04