Fort Fairfield, the gage there being discontinued
PREDICTING ICE JAM POTENTIAL
in 1910. A gage located upstream in the town of
Although predicting ice jams and their severity
Washburn, Maine, has been in operation since
is still beyond the state of the art, it is sometimes
1930, however. Based on drainage area, the
possible to rate the likelihood of damaging ice
Washburn flow records have been transposed to
jam floods on the basis of historical observations.
the Fort Fairfield area.
Such a prediction mechanism could prove useful
The largest recorded discharge at the Wash-
in estimating the potential for ice jams in a given
burn gage was 43,400 ft3/s on 19 April 1983.
year, both for early warning of potential flooding
This would correspond to a discharge of about
and for determining whether advance measures
58,500 ft3/s at Fort Fairfield. Typical winter dis-
to limit ice-related flood damages are advisable.
charges for the Aroostook are on the order of
Using the method of Wuebben et al. (1992), we re-
1000 ft3/s. Ice jams occur during most years on
viewed weather and hydrologic data from 1970
the Aroostook River, and are frequently respon-
through the present to identify the winter season
sible for the maximum annual stages. In its
characteristics leading up to significant ice jam
study of local flood protection for the town of
events. In addition, six significant ice jam events
Fort Fairfield, NED (USACE 1987) determined
were examined separately.
that peak annual stages at the Washburn USGS
Table 2 presents the factors that we examined,
gage site resulted from ice jams in 22 out of 53
including freezing degree-days, snowfall and wa-
years, or 42% of the years reviewed. There were
ter discharge. Freezing degree-days can be used
significant ice jam floods in Fort Fairfield in
in a relatively simple equation to predict ice thick-
1932, 1936, 1940, 1973, 1976 and 1991. The record
ness h
flood stage at Fort Fairfield was caused by an ice
h = c (FDD)0.5
jam flood in April 1976.
(1)
Table 2. Ice jam potential analysis, Aroostook River at Fort Fairfield, Maine.
Ice
Snow
FDD*
thickness
Dmax
Qmax W
Qmax FF
DQmax
DQ10
DQ10Dmax
DQmaxDmax
Q10
(F)
(ft3/s)
(ft3/s)
Year
(in.)
(J.D.)†
(J.D.)
(J.D.)
(J.D.)
(J.D.)
(in.)
1970
2035
27
189
24,400
32,940
209
207
18
20
88
1971
2246
28
190
27,000
36,450
218
211
21
28
135
1972
2695
31
193
23,300
31,455
222
215
22
28
137
1973
2252
28
195
28,100
37,935
206
201
6
11
153
1974
2164
28
194
38,300
51,705
214
209
15
20
106
1975
2104
28
192
11,000
14,850
207
205
13
15
118
1976
2440
30
174
31,000
41,850
188
182
8
14
131
1977
2354
29
192
26,400
35,640
204
203
11
12
146
1978
2177
28
188
18,900
25,515
212
206
18
24
118
1979
1943
26
168
24,600
33,210
179
177
9
11
108
1980
1838
26
172
13,300
17,955
199
198
26
27
70
1981
1892
26
176
15,300
20,655
189
187
11
13
122
1982
2097
28
192
30,400
41,040
211
204
12
19
158
1983
1601
24
183
42,500
57,375
201
196
13
18
83
1984
2049
27
183
18,000
24,300
201
199
16
18
133
1985
2030
27
195
14,600
19,710
210
204
8
15
90
1986
2257
28
176
17,600
23,760
185
184
8
9
94
1987
2139
28
169
33,500
45,225
185
183
14
16
80
1988
1994
27
176
15,000
20,250
189
187
11
13
92
1989
2251
28
183
13,800
18,630
191
190
27
8
77
1990
2343
29
182
15,900
21,465
207
203
21
25
118
1991
1790
25
183
35,800
48,330
193
181
2
10
93
min 1601
24
168
11,000
14,850
179
177
2
8
70
max
2695
31
195
42,500
57,375
221
215
38
44
158
avg
2122
28
184
23,381
31,565
203
199
15
20
111
std dev 233
1.6
8.6
8,582
11,586
12
11
8
8
24
* Freezing degree-days.
† Julian Days.
4
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