For complicated
aquifer test analysis (boundary influence, variable rate,
multiwell test, partially penetrating wells etc.) aquifer
parameter estimation by analyzing
normal diagnostic
plots (timedrawdown,
distancedrawdown, timedistance drawdown) is often difficult, or
even impossible. Transformation of related flow equations allows to
plot drawdown graphs in such coordinates that make it possible to
apply graphical methods for parameter estimation.
Example of timedistancedrawdown graph for multiwell pumping test
at variable rate: parameter estimation by straightline method
on
(s / Q)  lg(t' / r'2)
plot. The ordinate axis is drawdown : rate ratio, the abscissa –
dimensionless time and distance.
Example of timedrawdown graph for partially penetrating well:
parameter estimation by straightline method on
s  1 / t0.5
plot.
Example of timedistancedrawdown graph for partially penetrating
well: parameter estimation by method of type line on
lg(ds)  lg(t / d2)
plot.
For semiinfinite
(profile bounded) or bounded (strip aquifer) conceptual schemes
instead of
basic
distancedrawdown graph
s
 lg(r),
the onedimension graph of drawdown in observation wells for
selected observation points is plotted (menu "Choose
> Time"). If time
points are not specified the program plots the graph for the last
measurement. Using the graph direct problem is solved: observed and
calculated data are compared for given parameters
values.
Example of drawdown vs observation well graph
s  well.
