Table 13. Known ice events during the period 1950 through 1990

with such important parameters as river hydrau-

cal records. Ice jams at North Bend are often asso-

lics and geometry. We used both the regression

ciated with ice jams at other study locations, and

approach and the threshold approach to develop

few jams occur at other locations in the absence of

a prediction model.

some ice event at North Bend. Therefore, the pre-

To select a site on which to base the predictive

dictive model developed for this study is based

model, the ice events described previously are

on USGS gaging station records for gage #0679600

summarized in Table 13 for the period 19501990.

(Platte River at North Bend) and NWS data for

Of the seven sites chosen for detailed analysis in

Columbus, Nebraska.

the Section 22 Study, the Platte River at North

The normalized stage (i.e. the ratio between

Bend provides the best combination of ice data

the stage and flood stage) was used as an indica-

and long-term stage, discharge and meteorologi-

tor of the severity of a given ice event. A high

Table 13. Known ice events during the period 1950 through 1990.

Loup River

Water

Loup River

at Columbus

Platte River

Platte River Platte River

Platte River

Platte River Platte/Elkhorn

Year

between Columbus and Genoa

at North Bend

at Big Island at Leshara North of Hwy 64 at Hwy 92

Confluence

1950

X

XX

1951

X

1952

XX

1953

X

1954

1955

X

1956

1957

1958

X

1959

X

1960

XX

1961

X

1962

XX

X

1963

X

1964

1965

XX

1966

X

XX

1967

1968

1969

XX

1970

X

1971

XX

1972

XX

1973

X

1974

XX

X

XX

1975

X

1976

X

1977

XX

X

1978

XX

X

XX

1979

XX

X

XX

X

1980

XX

1981

XX

1982

XX

X

XX

X

XX

1983

XX

1984

XX

X

XX

1985

XX

X

1986

XX

X

XX

X

1987

1988

X

XX

1989

XX

X

1990

Note: X

=

recorded ice event below flood stage

XX

=

recorded ice event above flood stage (not necessarily significant flooding)

25