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

maximum value in the data set; see fig. 9A), an error
that, in the actual data set, is associated with a well
that contributes little to total network pumpage. The
results of permitting large errors to be associated with
wells having large pumpage are severe, yielding a
mean of about 9.3 percent and standard deviation of
about 11.9 percent for K = 1 (fig. 11). For K = 2, the
mean decreases to 2.70 percent; for K = 3, it decreases
to 0.77 percent; for K = 4, it decreases to less than
0 percent; for K greater than about 10, the mean tends
to level off at approximately —0.91 percent. Likewise,
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the standard deviation levels off for K greater than 4 at
about 1.25 percent. The fact that the mean becomes
negative when K is greater than 4 indicates that the
large positive errors at a small number of wells have
little effect on total network pumpage; it is instead the
influence of negative errors for large - pumpage wells
(see figure 9) that is causing the mean to become nega-
tive as K increases. Imposing the restriction that
number of strata K be larger than 4 prevents the few
very large positive errors from being associated with
wells that have large pumpage.
_2 l
0 5 10 15 20 25 30 35 40 45 50 55
NUMBER OF STRATA
Figure 11. Graph showing relation of the mean and standard deviation of total network pumpage, in percent, to
the number of strata.
ESTIMATION OF TOTAL NETWORK PUMPAGE 37