Geology Reference
In-Depth Information
Measurements in Pumping well and Observation well
Time since pump started
Time intervals
(minutes)
(minutes)
0-5
1-5
5-60
5
60-120
10
120-360
(or till shut down) 20
Discharge Measurements
A pumping test requires correct measurement of discharge of the pumped
well at a constant discharge rate. The flow rate is measured at regular intervals
of time and adjustments made to keep it constant through deployment of (a)
integrating type of water meter installed in the pipe, (b) Orifice meter and
(c) 90° V-notch. Small discharges can also be measured by recording the
time taken to fill a known volume of container.
Discharge through a 90° V-notch
Q
= 1.38
H
2.5
, where
H
= head in m and
Q
= discharg
e in m
3
/sec.
Head H (cm)
Discharge Q (lpm)
2
4.7
4
26.5
6
73
8
149
10
255
12
414
15
725
20
1490
25
2580
30
4060
Estimation of Flow from Horizontal Pipes
A fairly close determination of the flow from full open pipes may be made
by measuring the distance the stream of water travels parallel to the pipe in
falling 12 inches vertically.
A
20
