The Winter Low-Flow Balance of the
Semiarid White River, Nebraska and South Dakota
MICHAEL G. FERRICK, NATHAN D. MULHERIN AND DARRYL J. CALKINS
charge and discharge are difficult hydrological
INTRODUCTION
parameters to quantify. Sophocleous and Perkins
Water resource development in semiarid re-
(1993) developed a coupled streamaquifer model
gions can lead to declining groundwater levels
with an annual time step and applied it to bound
and streamflow in valleys with permeable soils
the hydrologic budget imbalance resulting from
and interconnected surfacesubsurface flow sys-
irrigation development in Kansas. Lacher et al.
tems, without a corresponding decrease in pre-
(1994) measured streamflow, evaporation rates,
cipitation. Evapotranspiration losses, water with-
soil conductivities, pumping rates, and well
drawals, and irrigation return flow affect both
hydrographs to estimate the rate of aquifer re-
the stream and shallow groundwater levels. Soil
charge from the Santa Cruz River in Arizona.
and geologic characteristics determine the total
Abdulrazzak and Sorman (1994) used a water
near-surface aquifer storage, the groundwater re-
balance approach to estimate flood water losses
charge from precipitation, and the locations and
from ephemeral streams in arid regions, but large
rates of exchange between groundwater and sur-
spatial and temporal parameter variability intro-
face water. The simple characterization of basins
duced uncertainty in the results.
by drainage area and precipitation is useful only
Low flows typically occur in the same season
in homogeneous basins. Subbasin yields at times
each year. Late summer and winter are low-flow
of low flow can vary widely within a relatively
periods in the northern United States and south-
small basin as a result of diverse water-bearing
ern Canada (Melloh 1990, Rogers and Armbruster
properties of underlying soils and rocks (Schneider
1990, Wuebben et al. 1992). Kuusisto (1986) re-
1965, Gerard 1981). Riggs (1972) suggested low-
ported mean winter-to-summer low-flow ratios
flow discharge measurements at several locations
that decrease significantly with distance north in
along a stream to define the base flows and the
Finland. Winter has been generally considered a
hydrologic homogeneity or heterogeneity of a
hydrologically dormant period and has not been
basin. For a given basin, the annual precipitation
extensively studied. However, the exchange of
and its distribution in time and space determine
water between a river and its near-surface aqui-
the quantity of water in storage, and the air tem-
fers is most readily quantified during the winter
perature regime affects the rate of water loss
months. The winter low-flow water balance is sim-
through evapotranspiration and the storage of
plified because there is negligible evapotranspi-
water as snow and ice.
ration, irrigation water withdrawals and diver-
Planners need tools for evaluating the effect of
sions are halted, and precipitation occurs largely
proposed changes in water usage in a basin on
in the form of snow, minimizing the spatial and
river flow, potential aquifer yields, water quality,
temporal variability of runoff. A complication is
contaminant migration, and other issues (ASCE
that the ice produced in the river can be a large
1980). In regions with water shortages, an im-
component of the water balance for semiarid ba-
proved understanding of the effects of water con-
sins in even moderately cold regions.
sumption is especially important. During peri-
The White River in Nebraska and South Da-
ods of low streamflow, the surface water is gener-
kota, an uncontrolled tributary of the Missouri
River, has a basin of 26,400 km2, but typical win-
ally of groundwater origin, but groundwater re-
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