Geoscience Reference
In-Depth Information
Fig. 10.31 Data points
dt
plotted against
Q
observed during the period 1961-1974 on Tonkawa Creek in
Oklahoma, with the lower envelope lines with slopes 1 and 3, respectively, in accordance with Equation
(10.157). The drainage area of this basin is
A
−
dQ
/
67 km
2
, the total length of all stream channels is
=
L
=
70 km, and the estimated mean depth of the surface aquifers is
D
=
1.6 m. (From Brutsaert and
Lopez, 1998.)
never occur) if the entire watershed were initially and uniformly saturated. In natural
catchments, the exact form of the base flow function
Q
Q
(
t
) is usually unknown,
especially when the characteristics of the riparian aquifers deviate markedly from those
of the idealized cases considered above in Sections 10.3, 10.4 and 10.5. Thus, beside the
avoidance of the time origin problem, the procedure based on Equations (10.155) and
(10.156) also has the advantage that it will give some insight into which of the above
theoretical expressions may be applicable, if at all. Unfortunately, however, because it
involves derivatives, this procedure is also sensitive to unavoidable inherent errors in
the data. It is therefore advisable to constrain such envelopes somewhat on the basis of
available theoretical considerations, as shown next.
=
