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Walker, John F.; Saad, David A.; Krohelski, J. T. / Optimization of ground-water withdrawal in the lower Fox River communities, Wisconsin
[DNR-122] (1998)

Ground-water flow system,   pp. 5-7 PDF (1.6 MB)


Page 5


from a regional perspective. To provide a regional
approach, the use of an optimization model was pro-
posed to the Wisconsin Department of Natural
Resources (WDNR). In 1994, the U.S. Geological Sur-
vey in cooperation with WDNR initiated a study of
ground-water management alternatives using a previ-
ously developed ground-water flow model, optimiza-
tion techniques, and water-use projections provided by
the CBCWC and ECWRPC.
    Many studies have helped to define the ground-
water resources of the Lower Fox River Valley and
document the status of the ground-water system (Con-
lon, 1998; Batten and Bradbury, 1996; Consoer
Townsend & Associates Inc., 1992; Feinstein and
Anderson, 1987; Krohelski, 1986; Olcott, 1966;
Knowles, 1964; Knowles, Dreher, and others, 1964;
LeRoux, 1957; Drescher, 1953). Unlike previous stud-
ies, however, the present study attempts to determine if
the sandstone aquifer is capable of providing the water
demands of a growing population in the Lower Fox
River Valley.
    The purpose of this report is to demonstrate that
efficient allocation of ground-water resources is feasi-
ble in the Lower Fox River Valley using ground-water
optimization modeling. In the context of this report,
optimization refers to maximizing withdrawals while
limiting drawdown to specified levels. The techniques
are applied to the regional ground-water model devel-
oped previously for the Lower Fox River Watershed
(Conlon, 1998) and focus on management in two areas:
the Central Brown County area and the Fox Cities area.
    Optimization modeling replaces the trial-and-error
approach by identifying potential solutions based on a
specified objective from a management plan. The tech-
nique quantifies solutions and allows comparison of
solutions ranging from optimal to those that are clearly
inferior or not feasible. In this report, optimization
modeling is used to evaluate specific management
plans with the objective of maximizing well yields
while satisfying pre-defined constraints, such as not
allowing water levels to decline below specified levels.
GROUND-WATER FLOW SYSTEM
    Ground water in the Lower Fox River Basin
moves through either shallow, local flow systems, or
through a deeper, regional flow system that is highly
confined in the Lower Fox River Valley. The geohy-
drology of the model area, water-use projections and
descriptions of pumping wells are described briefly in
this section. The geohydrology is described in more
detail elsewhere (Conlon, 1998).
Description of Modeled Area
    A previously developed ground-water flow model
(Conlon, 1998), that includes the major ground-water
pumping centers of the Central Brown County area and
the Fox Cities area in the Lower Fox River watershed
(fig. 1), was used for the optimization procedure. The
modeled area extends to the north of the city of Green
Bay and to the south of the city of Fond du Lac. The
western extent includes the Wolf River and upper Fox
River, the two largest rivers in the model area. The
eastern extent includes part of Lake Michigan.
Geology
    Unconsolidated deposits of Quaternary age overlie
the bedrock and consist of sediments of glacial, allu-
vial, and lacustrine origin. Glacial deposits in the
model area include tills, outwash, and extensive lacus-
trine deposits. Glacial deposits ranging from 0 ft thick
in the west to more than 100 ft in the river valley cover
the bedrock in most of the model area. Recent alluvial
and lacustrine deposits are also present in river valleys
and lakes, respectively.
    Sedimentary rock of Cambrian and Ordovician
age underlie the unconsolidated deposits in the western
part of the model. In the east, sedimentary rock of Sil-
urian age underlie the unconsolidated deposits. With
the exception of the Maquoketa Shale, most sedimen-
tary rocks consist of sandstone and dolomite. Crystal-
line rock of Precambrian age underlies the sedimentary
rock in most of the model area (fig. 4) and directly
underlies the glacial deposits in the northwestern part
of the area.
Hydrology and Ground-Water Movement
    The unconsolidated deposits and sedimentary rock
in the model area have been grouped into aquifers and
confining units (Conlon, 1998). The sedimentary rock
beneath the S innipee Group forms the sandstone aqui-
fer and the Maquoketa Shale and Sinnipee Group form
a confining unit. Above the confining unit, the uncon-
solidated deposits and dolomites form an upper aquifer
GROUND-WATER FLOW SYSTEM      5


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