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 8. Estimates of mean differences in pumpage between power conversion coefficient approach and totalizing flowmeter
for each combination of fixed effects of method, make, and type
[NS, mean is not significantly different from zero at the 5- percent significance level; S, mean is significantly different from zero at the 5- percent significance
level; the mean and the standard error can be expressed as a percent difference by multiplying the respective value by 1001
Method Mean
Standard
error
Significance at
the 5- percent
level
Method Mean
Standard
error
Significance at
the 5- percent
level
Discharge distribution type = O
Discharge distribution type = O
Make of totalizing flowmeter = M
Make of totalizing flowmeter = BSX
C — 0.0097
0.0058
NS
C 0.0106
0.0080
NS
M —.0149
.0059
S
M .0055
.0080
NS
P —.0263
.0059
S
P —.0060
.0080
NS
Discharge distribution type = CLS
Discharge distribution type = CLS
Make of totalizing flowmeter = M
Make of totalizing flowmeter = BSX
C .0040
.0068
NS
C .0244
.0094
S
M —.0011
.0070
NS
M .0192
.0096
NS
P —.0126
.0069
NS
P .0078
.0095
NS
SOURCES OF DISCREPANCY BETWEEN
PUMPAGE ESTIMATES
The analysis of variance procedures applied to
instantaneous discharge and pumpage data provided
information on the mean differences in well discharge
(diffQ) and pumpage (diffP) and on the variance of
diffQ. It is clear, however, that these analyses are not
independent of each other. Part of the discrepancy
between total pumpage computed by the PCC
approach and pumpage measured by the TFM comes
from differences between measurements made by
portable flowmeters and TFM's and differences
between these meters are reflected in differences
between the paired instantaneous discharge measure-
ments. In other words, one would expect that part of
the variability in diffP is being caused by variability in
diffQ. However, there are other possible sources of
discrepancy between total pumpage obtained by the
two approaches. The following section of the report
enumerates several possible sources of discrepancy.
For most of these sources, data are not available to
estimate exactly how much of the discrepancy is
coming from each source. Nevertheless, it is important
to explicitly discuss what the possible sources of error
are, possibly providing guidance for future data -
collection efforts. One important source of potential
discrepancy that is discussed in some detail is
temporal variability of the PCC. Some data are avail-
able to obtain an estimate of the contribution of this
component to the difference between pumpage by the
two approaches.
Specifically, this section of the report discusses
(1) possible sources of discrepancy that result in
differences between ground -water pumpage as
measured by a TFM and ground -water pumpage as
obtained by the PCC approach; and (2) with available
data, how might the temporal variability of PCC's
effect the differences in pumpage.
Primary Results
There are several potential sources of discrep-
ancy between pumpage as measured by a TFM and
pumpage as computed by the PCC approach. These
include errors in instantaneous discharge as measured
by a TFM and a portable flowmeter, TFM pumpage
errors, errors in the electrical power meter, and
temporal variability of the PCC. Each may account for
a portion of the discrepancy between pumpage as
measured by a TFM and pumpage as computed by the
PCC approach. It is not possible with data currently
available to give reliable estimates of the magnitude of
each of the components of pumpage error. Additional
data and evaluation of these data are needed to define
long -term temporal variations in PCC's and TFM's, as
well as defining other sources of discrepancy in
pumpage estimates.
Limited data are available to provide an estimate
of errors caused by temporal variability of PCC's. The
standard deviation associated with year -to -year vari-
ability of these PCC's was estimated to be about
30 Comparison of Two Approaches for Determining Ground -Water Discharge and Pumpage in the
Lower Arkansas River Basin, Colorado, 1997 -98