Ice Jam Flooding and Mitigation
Lower Platte River Basin, Nebraska
KATHLEEN D. WHITE AND ROGER L. KAY
with a discharge of 119,000 cubic feet per second
INTRODUCTION
(cfs) and a gage height of 14.42 ft. The 1993 event
Severe flooding due to the combination of ice
caused flooding in the area between the Loup and
jams and rapid snowmelt occurred within the
Platte Rivers and nearly overtopped the levee on
Lower Platte River basin in Nebraska during
the north bank of the Loup River. At Ashland,
March 1993. The two areas most affected were
two major levee breaks occurred, flooding about
along the south side of the Loup River at Colum-
14,000 acres of farmland on the east side of the
bus and just downstream from the confluence of
Platte River. A number of houses were destroyed
the Elkhorn and Platte Rivers near Ashland (Fig.
along the west side of the river, and the well fields
1). Stages at Columbus exceeded the previous peak
for the city of Lincoln were threatened. Fourteen
stage set in August 1966, an open-water event
counties were included in the disaster area.
The overall basin damages during the
SOUTH DAKOTA
March 1993 event were more than
million, including road closures; road
NEBRASKA
failures; damage to bridge abutments
Sioux
Log
and water supplies; flooding of residen-
City
an
tial, agricultural, industrial and com-
Cr.
Ca
lam
mercial areas; and damage to levees,
R.
Norfolk
us
dikes and other river- training structures.
West Point
No
rth
Over 74,000 acres were damaged by
R.
3
North
sediment deposited during the floods
Bend
1
Fremont
Genoa
Waterloo
2
(USAED, Omaha 1993).
Lo
So
up
Columbus
uth
Omaha
The March 1993 ice event was the
R.
4
7
Lo
R.
up
5
most damaging event since February
Grand
er
R.
6
Island
Lincoln
iv
1978, when over million in dam-
R
Ashland
ages resulted from ice-jam flooding
IOWA
Platte
(USAED, Omaha 1978). Flood damages
MISSOURI
in 1978 were particularly severe in the
ValleyFremont area, when an ice jam
overtopped and breached the Union
KANSAS
1 Genoa to Columbus
Dike, flooding 27,000 acres in Dodge
2 Hwy. 79 at North Bend
and Douglas Counties. Substantial dam-
ages were also incurred that year due
Study
3 Big Island at Fremont
Area
to an ice jam that formed just down-
4 West channel at Leshara
NEBRASKA
stream from the confluence of the Platte
5 1.5 miles north of Hwy. 64 Bridge
and Elkhorn Rivers near Ashland. In
6 Hwy. 92 Bridge
all, over 60,000 acres were flooded, and
7 Confluence of Platte and Elkhorn R.
20 counties were included in the disas-
Figure 1. Lower Platte River Section 22 study sites.
ter area for the 1978 event.
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