Flood Risk and Vulnerability Analysis Project - Atlantic Climate ...

Return Periods (years)
Duration 2 5 10 20 25 50 100
5 min 4.4 6.3 7.6 8.8 9.2 10.4 11.5
10 min 6.5 9.4 11.2 10.8 13.6 15.4 17.1
15 min 7.8 11.3 13.6 15.9 16.6 18.7 20.9
30 min 10.4 15.2 18.4 21.5 22.5 25.5 28.5
1 h 13.3 18.4 21.7 24.9 25.9 29.0 32.1
2 h 18.3 23.7 27.4 30.8 31.9 35.3 38.7
6 h 30.1 37.9 43.1 48.1 49.7 54.5 59.3
12 h 38.7 49.0 55.8 62.3 64.3 70.7 77.0
24 h 47.3 62.4 72.4 82.0 85.0 94.4 103.7
Table 3-10. Updated IDF values for Gander based on data to 2011
Return Period (years)
Duration 2 5 10 20 25 50 100
5 min 3.9 5.6 6.6 7.6 8.0 9.0 10.0
10 min 5.7 8.5 10.3 12.1 12.7 14.4 16.1
15 min 6.9 10.3 12.6 14.8 15.5 17.7 19.8
30 min 8.8 13.3 16.3 19.2 20.1 22.9 25.7
1 h 11.2 15.7 18.6 21.5 22.4 25.2 27.9
2 h 14.5 19.5 22.8 26.0 27.0 30.1 33.2
6 h 24.1 31.1 35.7 40.2 41.6 45.9 50.2
12 h 32.1 40.3 45.8 51.0 52.7 57.8 62.9
24 h 40.7 51.4 58.4 65.2 67.4 74.0 80.6
Table 3-11. Updated IDF values for Goose Bay based on data to 2009
except for 24-hr precipitation which is to 2011.
In a concurrent study conducted by AMEC, IDF values were projected into the future (2020,
2050 and 2080) for St. John‟s, Stephenville and Deer Lake, all on the island of Newfoundland.
At the 24 hr duration the IDF values for Deer Lake and Stephenville (both in WRMD‟s West
Region) increased by a greater amount than St. John‟s (WRMD East Region). IDF values at a
24 hr duration for Deer Lake increased from 2-4 % in 2020 to 4-7 % in 2080. The IDF values for
Stephenville showed consistent increases near 4-10 %. However, the 24 hr duration IDF values
for St. John‟s only increased from 1 % in 2020 to 2-4 % in 2080. While the scale of increase
may not precisely match the values given in Table 3-8, they are not inconceivable considering
the values in Table 3-8 are for much larger geographical area versus points and for only two
seasons using a somewhat conservative SRES scenario (A2). Also, the increase in precipitation
at Deer Lake and Stephenville compared to St. John‟s is captured in the West vs. East region
(respectively) values.
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