Perched River
White River
at Oglala
Q
Winter
Period
Flow Loss
to Groundwater
Figure 9. Hypothetical flow loss from
Lower Bound
the river to the groundwater for a
perched river. The mean annual hydro-
graph for the White River at Oglala is used
as a reference. The flow loss during winter
extended over the year provides a lower
bound for the annual flow loss.
N
D
J
F
M
A
M
J
J
A
S
O
Coupled
Hydrologic System
White River
at Oglala
Winter
Q
Period
Net Groundwater Loss
Figure 10. Hypothetical flow exchange
Groundwater
Withdrawal
between the river and the groundwater
for a coupled hydrologic system. The
mean annual hydrograph of the White
River at Oglala is used as a reference. The
curve of groundwater withdrawal is based
on irrigation data of Sando (1991) and rep-
resents losses above recharge from precipi-
tation and return flow. The lighter shad-
ing represents volumetric loss from the
river, in balance with net groundwater loss
River to Groundwater
(diagonal shading), and the darker shad-
Groundwater to River
ing represents volumetric groundwater to
river exchange.
N
D
J
F
M
A
M
J
J
A
S
O
locity for fine sands and silts (Bear 1972). The
the remainder of the subbasin were White Clay
evidence supports the hypothesis of a predomi-
Creek (WCC), two times White Clay Creek
nantly perched river through this reach. Small,
(2WCC), and the Little White River at WR. In a
variable flow losses and yields from the other two
given month with no additional tributary inflows,
subbasins with significant uncertainties suggest
the subbasin yield or river flow loss given in Table
more complex coupled hydrologic systems in these
3 is the groundwater exchange. With few excep-
reaches. Additional measurements of relative
tions the CrawfordOglala reach had consistent
riveralluvial aquifer levels over the year, local
flow losses over the channel area of between 4.0
and 4.9 107 m3/s-m2, a midrange seepage ve-
groundwater withdrawals, and tributary inflows
13
Previous Page
