river locations in Table 1 were obtained from re-
ed that "in the upper part of the valley" a consid-
cent maps using a map wheel. The White River is
erable flow will frequently disappear within 35
generally more sinuous than the Little White River,
km due to groundwater recharge. The annual
with generally higher river/linear distance ratios.
hydrograph of monthly average flows at Kadoka
The Little White River below Martin has an aver-
also has double peaks and the same general shape
age slope of 0.0020, more than twice the 0.00087
as that at Oglala, with flow decreasing through
of the White River below Crawford.
the fall and into midwinter. However, the increase
Sando (1991) detailed the surface water diver-
in discharge between these gages is generally sig-
sions and groundwater withdrawals for irriga-
nificant, due largely to flow contributions of the
tion over the last 50 years in the White River ba-
perennial creeks. The yield of the Little White River
sin upstream of the South Dakota state line. Wa-
basin as surface water is indicated by gage White
ter use is zero for November through April but
River (WR) at 23 km above the White River
currently averages 50% of the flow at the state
confluence. Spring flows on the Little White are
line gage for the remainder of the year. All tribu-
high and variable, while fall and winter flows are
taries in the basin above the state line are ephem-
lower and more stable. Summer flows are occa-
eral (Sando 1991) and, more generally, streams in
sionally high, but generally consistent with the
the White River basin are unreliable sources of
groundwater-inflow-dominated fall and winter
water (Ellis and Adolphson 1971). Most stream-
conditions. The annual hydrographs of monthly
flow occurs in response to precipitation and run-
average flow for all gages in the Little White ba-
off during spring and early summer, with a large
sin have single peaks in either March or April.
component of the March flow due to snowmelt.
The monthly average White River flow at the
Rothrock (1942) reported extensive field investi-
Oacoma gage near the mouth can vary dramati-
gations throughout the river valley over a 43-km
cally between seasons, especially spring and sum-
reach from Kadoka downstream. The alluvium
mer, and years. Winter flows are more consistent
and extremely low by comparison, with 0.6 m3/s
there is between 7.5 and 12.5 m deep, composed
at Crawford and 2.6 m3/s from the Little White
mostly of sands and gravels, overlying Pierre shale.
Near-surface aquifers in the alluvial deposits are
River equaling almost the entire flow at Oacoma
permeable and readily exchange water with the
from subbasins representing only 18% of the total
river. The groundwater level is below the river
drainage area.
surface during dry seasons, rising to river level
Figure 2 provides a breakdown of annual and
during wet seasons. When river flow ceases, deep
winter average water yields to the river of se-
pools remain wet, reflecting the water table level.
quential subbasins of the White River basin, de-
lineated by the primary streamflow gages. The
Short reaches of the perennial Bear-in-the-Lodge,
highest annual and winter water yields in the en-
Porcupine, Wounded Knee, and White Clay Creeks
tire basin occur in a subbasin of the Little White
intercept the water table, allowing groundwater
River between Martin and Rosebud. This subbasin
inflow to supplement runoff. The larger tributar-
has an annual water yield 2.5 times greater, and a
ies supply groundwater with a different chemical
winter yield 8.7 times greater, than that of the
signature directly to the alluvium of the White
complete basin. The ratio of winter to annual av-
River. The wind-blown sand deposits in the Little
erage discharge is greater than 1 for the subbasin
White River basin above Rosebud are permeable,
above Crawford and greater than 0.7 for all
minimizing surface runoff and providing more
subbasins of the Little White River above the gage
consistent flows than are found elsewhere in the
at Rosebud. However, for most of the main-stem
basin (Ellis et al. 1971).
White River and the Little White River below
The subbasin above the Crawford gage pro-
Rosebud, the winter flows are only 23 to 35% of
vides stable river flows throughout the year. Sig-
the annual average. The subbasin between
nificant groundwater input to the river and mini-
Crawford and Oglala has the lowest annual yield
mal surface runoff cause this stability, which is
in the entire basin and a negative winter yield.
interrupted only occasionally by large spring and
Other subbasins with low yields both annually
summer events. The annual hydrograph of
and in winter are the Little White below Rosebud
monthly average flows at Oglala has peaks in both
and the White below Kadoka. Unlike the other
March and June and low flows in the fall and
main-stem subbasins below Crawford, the
winter. The average winter flow at Oglala is less
subbasin between Oglala and Kadoka has a high
than that at Crawford (Table 1), even though the
annual yield and a positive winter yield. The
basin is seven times larger. Rothrock (1942) report-
4
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