Comparison of Two Approaces for Determining Ground-Water Discharge and Pumpage in the Lower Arkansas River Basin Colorado 1997-98

• Description: Comparison of Two Approaces for Determining Ground-Water Discharge and Pumpage in the Lower Arkansas River Basin Colorado 1997-98
• State: CO
• Basin: Arkansas
• Author: Dash, Russell; Troutman, Brent; Edelmann, Patrick
• Title: Comparison of Two Approaces for Determining Ground-Water Discharge and Pumpage in the Lower Arkansas River Basin Colorado 1997-98
• Water Supply Pro - Doc Type: Report/Study

Table 5. Comparison of State - approved power conversion coeff icient (PCC) measurements (1994 -97) to the site average
PCC measurements made during 1998
[PCC, power conversion coefficient]
Number of PCC
Number of PCC
Minimum and comparisons within
comparisons within
State - approved PCC Number of PCC
maximum percent 10 percent of 1998 site
20 percent of 1998 site
measurement year comparisons
difference average PCC
average PCC
Number Percent
Number Percent
1994
37
-57
18
49
25
68
90
1995
26
-37
8
31
11
42
211
1996
22
-46
10
45
17
77
27
1997
18
-18
14
78
16
89
73
1994 -97 103 -57 50 48 69 67
211
COMPARISON OF GROUND -WATER
PUMPAGE ESTIMATES
A comparison of ground -water pumpage
measured using TFM's to ground -water pumpage esti-
mates determined by the PCC approach was made by
evaluating the differences in pumpage and deter-
mining whether the differences are statistically signifi-
cant. The pumpage estimates were calculated using
PCC measurements made at network sites during
1998. This was done by dividing the total 1998 power
consumed at each site during the monitoring period, in
kilowatthours, by each unique PCC measurement
made at that same well site during 1998. The TFM
derived pumpage measurement at each well was deter-
mined as the difference between TFM readings made
at the beginning and the end of the monitoring period.
The monitoring period was the same for the TFM and
PCC approach. Because it was determined that the
method of portable flowmeter, make of TFM,
discharge distribution type, and the site, date, and
random error were identified as sources of variation,
an additional level of data analysis was required.
This section of the report presents (1) the
magnitude in differences in ground -water pumpage
between TFM and PCC estimates; (2) an estimate of
the overall mean difference in pumpage and whether
the overall mean difference is significantly different
from zero; (3) an estimate of the mean differences for
each combination of portable flow meter, make of
TFM, and discharge distribution type, and whether
these mean differences are significantly different from
zero. The comparison of ground -water pumpage was
based on 553 paired measurements made at 103 wells
during 1998.
Primary Results
The analysis of variance on the differences in
pumpage was performed using a rank transformation
on 553 paired pumpage measurements made at
103 wells during 1998. About 80 percent of the
differences in pumpage between the TFM and PCC
approach were less than 10 percent. The overall mean
difference in pumpage was 0.01 percent, indicating no
significant difference on average between pumpage as
measured by TFM and pumpage as computed by the
PCC approach. For varying site characteristics (the
method of portable flowmeter, the make of TFM, and
type of discharge distribution system), mean differ-
ences in pumpage were generally less than ±3 percent
and, for most instances, the mean differences in total
pumpage were not significantly different from zero at
the 5- percent level.
Details of Analysis and Results
For each paired pumpage measurement made at
a well, the difference in ground -water pumpage, diffP,
was computed as:
COMPARISON OF GROUND -WATER PUMPAGE ESTIMATES 25