Table 5. Discharge deficit record.
Max
Length
AFDD
Max
Length
AFDD
deficit
of period
at max
deficit
of period
at max
(1000 ft3/s)
(1000 ft3/s)
(C)
(C)
Date
(days)
Date
(days)
19 Jan 71
2.5
18
467.8
20 Dec 80
0.7
2
72.5
1 Feb 71
3.3*
5
553.1
2 Feb 81
3.5*
2
258.3
9 Feb 71
1.9
5
657.2
9 Feb 81
2.7
4
323.9
22 Dec 71
0.8
1
151.9
20 Dec 81
0.8
2
90.0
15 Jan 72
5.5*
3
343.3
10 Jan 82
4.0*
3
305.6
20 Jan 72
5.0
10
375.3
18 Jan 82
3.0
4
433.9
10 Feb 72
1.0
10
676.4
24 Jan 82
2.0
3
504.4
15 Feb 72
0.5
2
716.9
5 Feb 82
1.0
4
649.2
18 Feb 72
3.2
2
727.2
18 Jan 83
0.3*
1
135.0
10 Jan 73
0.8*
3
390.0
13 Dec 83
0.3
1
190**
11 Jan 74
4.0*
14
420.3
22 Dec 83
11.5*
11
370**
4 Feb 74
0.4
2
509.2
6 Feb 84
0.7
1
750**
13 Jan 75
6.2*
4
201.7
25 Dec 84
1.0
1
128.6
6 Feb 75
3.2
3
366.9
30 Dec 84
0.7
1
157.2
17 Dec 75
0.9
1
102.5
2 Jan 85
1.3
2
200.0
8 Jan 76
8.0*
7
289.2
12 Jan 85
0.8
2
277.8
17 Jan 76
1.7
1
367.2
15 Jan 85
1.0
2
303.6
27 Jan 76
0.3
1
420.8
21 Jan 85
2.6
4
363.9
5 Feb 76
2.6
4
455.8
31 Jan 85
4.0*
16
457.8
11 Dec 76
0.6
1
111.1
25 Dec 85
4.1*
3
296.4
21 Dec 76
0.8
1
126.1
29 Dec 85
0.7
2
322.2
18 Jan 77
0.3
1
480.6
7 Jan 86
3.1
3
382.2
30 Jan 77
4.0*
7
579.4
27 Jan 86
0.7
1
407.2
6 Dec 77
4.6*
6
26.9
11 Feb 86
1.2
6
482.5
2 Jan 78
0.6
1
235.6
21 Feb 86
1.3
2
570.0
9 Jan 78
0.7
1
323.6
5 Jan 88
7.4*
11
132.8
17 Jan 78
1.0
2
466.4
13 Jan 88
2.0
2
263.9
28 Jan 78
1.0
2
650.3
21 Jan 88
1.4
4
311.9
25 Jan 79
2.5*
9
610.8
26 Jan 88
0.8
1
363.6
8 Jan 80
6.8*
2
101.9
2 Feb 88
0.8
2
424.2
10 Jan 80
0.3
1
135.3
8 Feb 88
0.5
2
519.4
12 Jan 80
1.2
1
152.5
13 Feb 88
0.5
2
599.7
29 Jan 80
0.9
5
226.9
* Annual maximum
** Estimated
in Figure 9. It can be seen that nearly half the
The discharge deficit record can be further ana-
maximum deficits were 1000 ft3/s or less. The
lyzed by grouping the recorded discharge deficits
annual maximum return interval can be found by
into half-month periods, as shown in Table 6. It can
selecting the maximum discharge deficit that oc-
be seen that impact periods do not occur every year
curred during each winter. The return interval is
during each half month. The most likely half
found by assigning each maximum discharge defi-
months are 1631 December (61%), 115 January
(55%) and 1631 January (61%). Again, the return
interval for each half-month period is found in the
the rank of the deficit and N is the total number of
data points available. The return interval is then 1/
same manner as the annual maximum return in-
(1P). The annual maximum return interval is
terval. The annual maximums occurring in each
shown in Figure 10. It can be seen that the distribu-
half-month period are shown in Figures 11 through
tion is nearly normally distributed, and that there
14. The periods 115 December and 1628 February
is one apparent outlier. This outlier occurred on 22
were not plotted because there were too few data
December 1983 and has a value of 11,500 ft3/s. This
points. We can see that, in large part, the data are
is by far the largest ice-impacted discharge deficit
normally distributed except for the period 1631
recorded during the period of record.
December. The data for this period seem to suggest
12
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