PROBLEM; BASED ON THEIS METHOD:-
A Well penetrating a confined aquifer is pumped at a constant rate of discharge of 2270 lit/min.
Draw-downs during the pumping periods are measured in an observation well 45m from the
pumped well at time varying from 2 min to 6hrs and recorded as under. Determine the
formation constants T (in lit/day/m) and S.
Sr. Time elapsed since being of Drawdown in Observation well
No. pumping ‘t’ min. ‘S’ m.
1 0 0
2 2 0.366
3 3 0.579
4 4 0.747
5 5 0.884
6 6 1.026
7 7 1.113
8 8 1.250
9 10 1.402
10 14 1.677
11 18 1.875
12 24 2.134
13 30 2.362
14 40 2.592
15 50 2.744
16 60 2.896
17 80 3.064
18 120 3.140
19 180 3.201
20 240 3.247
21 360 3.293
Values of wu (well function) for values of u
U 1 2 3 4 5 6 7 8 9
*1 0.219 - - - - - - - -
*10-1 1.82 1.22 0.91 0.70 0.56 0.45 0.37 0.31 0.26
*10-2 4.04 3.35 2.96 2.68 2.47 2.30 2.15 2.03 1.92
*10-3 6.33 5.64 5.23 4.95 4.73 4.54 4.39 4.26 4.14
, For Unsteady flow in confined aquifer Mr. C.V.Theis has invented a graphical method for
solution of formation constants i.e. S and T. This method modified by (i) Copper & Jacob (ii)
Chow’s method.
Advantage: (1) Shorter pumping period
(2) Use to find S & T
(3) Only one observation well required to analysis work.
(4) No specific assumption
Solution: -
Q = 2270 lit/min 1 m3 = 1000 lit
= 2.270 m3/min 1 day = 24 hr x 60 min
= 3268.80 m3/day = 1440
Hydraulician’s value
If u = 1 x 10-3 then W = 6.33
u = 2 x 10-3 then W = 5.64
1. Draw type curve by plotting u on x axis and w (u) on y axis.
2. Draw data curve by plotting r2/t in m2/day on x axis and s = (ho – h) drawdown in meter
on y axis.
3. Prepare impression of data curve on tracing paper.
4. Put or super imposed data curve (tracing paper) on type curve.
5. By keeping ordinate axis must be parallel such as most of the points of observation data
full on a segment of type curve.
6. By trial and error repeat as per point no.5.
7. From graphs plotted, co-ordinates of match point obtained.
2
r
8. Get value from u, w (u), S,
t
9. Any corner of log- log cycle gives above 4 values to get answer.
A Well penetrating a confined aquifer is pumped at a constant rate of discharge of 2270 lit/min.
Draw-downs during the pumping periods are measured in an observation well 45m from the
pumped well at time varying from 2 min to 6hrs and recorded as under. Determine the
formation constants T (in lit/day/m) and S.
Sr. Time elapsed since being of Drawdown in Observation well
No. pumping ‘t’ min. ‘S’ m.
1 0 0
2 2 0.366
3 3 0.579
4 4 0.747
5 5 0.884
6 6 1.026
7 7 1.113
8 8 1.250
9 10 1.402
10 14 1.677
11 18 1.875
12 24 2.134
13 30 2.362
14 40 2.592
15 50 2.744
16 60 2.896
17 80 3.064
18 120 3.140
19 180 3.201
20 240 3.247
21 360 3.293
Values of wu (well function) for values of u
U 1 2 3 4 5 6 7 8 9
*1 0.219 - - - - - - - -
*10-1 1.82 1.22 0.91 0.70 0.56 0.45 0.37 0.31 0.26
*10-2 4.04 3.35 2.96 2.68 2.47 2.30 2.15 2.03 1.92
*10-3 6.33 5.64 5.23 4.95 4.73 4.54 4.39 4.26 4.14
, For Unsteady flow in confined aquifer Mr. C.V.Theis has invented a graphical method for
solution of formation constants i.e. S and T. This method modified by (i) Copper & Jacob (ii)
Chow’s method.
Advantage: (1) Shorter pumping period
(2) Use to find S & T
(3) Only one observation well required to analysis work.
(4) No specific assumption
Solution: -
Q = 2270 lit/min 1 m3 = 1000 lit
= 2.270 m3/min 1 day = 24 hr x 60 min
= 3268.80 m3/day = 1440
Hydraulician’s value
If u = 1 x 10-3 then W = 6.33
u = 2 x 10-3 then W = 5.64
1. Draw type curve by plotting u on x axis and w (u) on y axis.
2. Draw data curve by plotting r2/t in m2/day on x axis and s = (ho – h) drawdown in meter
on y axis.
3. Prepare impression of data curve on tracing paper.
4. Put or super imposed data curve (tracing paper) on type curve.
5. By keeping ordinate axis must be parallel such as most of the points of observation data
full on a segment of type curve.
6. By trial and error repeat as per point no.5.
7. From graphs plotted, co-ordinates of match point obtained.
2
r
8. Get value from u, w (u), S,
t
9. Any corner of log- log cycle gives above 4 values to get answer.
