Canadian Dam Association Bulletin - Summer 2017 - 26

1. INTRODUCTION
On September 20-21, 2010,
Hurricane Igor struck Cape Race,
Newfoundland as a category 1 hurricane, resulting in major flooding
and widespread power outages. Igor
had estimated maximum sustained
winds of at least 120 km/h with gusts
up to 170 km/h. Hurricane Igor was
the third wettest event recorded in
Canadian history with 236 mm of rain
recorded at St. Lawrence. The impacts
of the storm were widespread on the
Burin and Bonavista Peninsula's of
Newfoundland and Labrador.
Newfoundland Power (NP) own and
operate five hydroelectric developments in the vicinity of the hardest
hit regions; Fall Pond, West Brook,
and Lawn on the Burin Peninsula
and Port Union and Lockston on the
Bonavista Peninsula. Hurricane Igor
caused a significant amount of structural damage to the Lawn and Port
Union developments, but Lockston,
Fall Pond and West Brook survived
with minor damage such as road
washouts, minor erosion and minor
water ingress in powerhouses. This
study updates the estimates of flood
discharges generated at the Port
Union and Lawn developments during Hurricane Igor and compares
them with respective flood frequency
estimates to assess the severity of the
event. Both impacted developments
are about 250 km apart.
The Port Union hydroelectric system is located on the
Bonavista Peninsula of the Island of
Newfoundland. The unit was commissioned in 1917 with a nameplate
capacity of 500 kW. The river system
is ungauged and drains an area of
about 79 km2 at Whirl Pond. Inflows
to the development are regulated
through a storage system comprising Long Pond and Whirl Pond reservoirs. The second hydroelectric unit,
Lawn hydroelectric development is
located on the Burin peninsula of the
island and has a nominal installed
capacity of 625 kW with a rated head
of approximately twenty (20) meters.
This development draws its inflows
from an ungauged watershed with a
26

drainage area of about 81 km 2. The
location of the two developments
relative to Environment Canada
meteorological sites and Water survey
of Canada streamflow gauged stations
is presented in Figure 1.

2. HURRICANE IGOR
Hurricane Igor was the strongest
tropical cyclone of the 2010 Atlantic
season and was the most damaging
hurricane in recent history for the
island of Newfoundland. Igor made
landfall near Cape Race around
3:00pm on September 21st. The center of the hurricane straddled the
east coast of the Avalon Peninsula
of Newfoundland from 3:00pm
to 5:00pm. Wind gusts of 84 and
88 kt were measured at Bonavista and
Sagona Island, respectively. Rainfall
totals generally ranged from 100 to
200 mm over eastern Newfoundland
with a maximum total of 238 mm at
St. Lawrence (Pasch 2011). The storm
trajectory is presented in Figure 2.
Hurricane Igor pelted Newfoundland with heavy rainfall and strong
winds as it approached the region
from the southwest. Based on media
reports the rainfall totals are representative of the 20 hours storm duration spanning September 20 and
21, 2010. St Lawrence and Bonavista
experienced the highest rain recorded
at the five stations and also indicative of the main direction of the
event. Both stations are close to the
impacted hydroelectric developments,
Lawn development located near

Figure 1: Climate stations that observed
rainfall amounts during Hurricane Igor

St. Lawrence climate station and Port
Union development close to Bonavista
climate station. The Port Union watershed, located near Bonavista, recorded
close to 200 mm of rain before the
gauge malfunctioned and the area
continued to receive heavy rain after
the gauge malfunctioned. As a result
of the reported malfunctioning at
Bonavista, an assumption that rainfall amounts observed at St. Lawrence
station are representative for the flood
event at Port Union development
seems reasonable.

3. HYDROLOGIC RESPONSE
Hurricane Igor impacted Newfoundland with heavy rainfall and
strong winds as it approached the
region from the southwest. The
event lasted for twenty (20) hours
and the two day storm rainfall depths
recorded at Environment Canada
climatic stations are presented in
Table 1. Environment Canada also
measures streamflow at their network
of river gauging stations managed
through the Water Survey of Canada.
The location of Environment Canada
flow monitoring station is presented
in Figure 1. The Hydrometeorological
Prediction Center of the National
Weather Service contoured rainfall
amounts resulting from Hurricane
Igor, in Figure 3, that illustrated the
greatest concentration of rainfall
was on the east side of the Burin
Peninsula, with rainfall amounts
reducing in more or less parallel lines
to the storm trajectory.

Figure 2: Best track positions for Hurricane
Igor, 8-21 September 2010 (Pasch 2011)

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Table of Contents for the Digital Edition of Canadian Dam Association Bulletin - Summer 2017

Board of Directors
President's Message
Roller Compacted Concrete Buttress at the Site C Clean Energy Project
Hurricane Igor's Impact on Newfoundland Power's Small Hydro
CDA Conference Heads to Kelowna!
CDA Directors & Officers - Call for Nominations
2017 CDA Awards - Call for Nominations
CDA Developing New Ways to Distribute Guidelines
Notice of Annual General Meeting
Time to Renew Your Membership
Buyers' Guide and Trade List
Canadian Dam Association Bulletin - Summer 2017 - intro
Canadian Dam Association Bulletin - Summer 2017 - 1
Canadian Dam Association Bulletin - Summer 2017 - 2
Canadian Dam Association Bulletin - Summer 2017 - 3
Canadian Dam Association Bulletin - Summer 2017 - 4
Canadian Dam Association Bulletin - Summer 2017 - 5
Canadian Dam Association Bulletin - Summer 2017 - 6
Canadian Dam Association Bulletin - Summer 2017 - Board of Directors
Canadian Dam Association Bulletin - Summer 2017 - 8
Canadian Dam Association Bulletin - Summer 2017 - President's Message
Canadian Dam Association Bulletin - Summer 2017 - 10
Canadian Dam Association Bulletin - Summer 2017 - 11
Canadian Dam Association Bulletin - Summer 2017 - Roller Compacted Concrete Buttress at the Site C Clean Energy Project
Canadian Dam Association Bulletin - Summer 2017 - 13
Canadian Dam Association Bulletin - Summer 2017 - 14
Canadian Dam Association Bulletin - Summer 2017 - 15
Canadian Dam Association Bulletin - Summer 2017 - 16
Canadian Dam Association Bulletin - Summer 2017 - 17
Canadian Dam Association Bulletin - Summer 2017 - 18
Canadian Dam Association Bulletin - Summer 2017 - 19
Canadian Dam Association Bulletin - Summer 2017 - 20
Canadian Dam Association Bulletin - Summer 2017 - 21
Canadian Dam Association Bulletin - Summer 2017 - 22
Canadian Dam Association Bulletin - Summer 2017 - 23
Canadian Dam Association Bulletin - Summer 2017 - Hurricane Igor's Impact on Newfoundland Power's Small Hydro
Canadian Dam Association Bulletin - Summer 2017 - 25
Canadian Dam Association Bulletin - Summer 2017 - 26
Canadian Dam Association Bulletin - Summer 2017 - 27
Canadian Dam Association Bulletin - Summer 2017 - 28
Canadian Dam Association Bulletin - Summer 2017 - 29
Canadian Dam Association Bulletin - Summer 2017 - 30
Canadian Dam Association Bulletin - Summer 2017 - 31
Canadian Dam Association Bulletin - Summer 2017 - 32
Canadian Dam Association Bulletin - Summer 2017 - 33
Canadian Dam Association Bulletin - Summer 2017 - 34
Canadian Dam Association Bulletin - Summer 2017 - 35
Canadian Dam Association Bulletin - Summer 2017 - CDA Conference Heads to Kelowna!
Canadian Dam Association Bulletin - Summer 2017 - 37
Canadian Dam Association Bulletin - Summer 2017 - 38
Canadian Dam Association Bulletin - Summer 2017 - 39
Canadian Dam Association Bulletin - Summer 2017 - 40
Canadian Dam Association Bulletin - Summer 2017 - 41
Canadian Dam Association Bulletin - Summer 2017 - 42
Canadian Dam Association Bulletin - Summer 2017 - 43
Canadian Dam Association Bulletin - Summer 2017 - 44
Canadian Dam Association Bulletin - Summer 2017 - 45
Canadian Dam Association Bulletin - Summer 2017 - CDA Directors & Officers - Call for Nominations
Canadian Dam Association Bulletin - Summer 2017 - 47
Canadian Dam Association Bulletin - Summer 2017 - 2017 CDA Awards - Call for Nominations
Canadian Dam Association Bulletin - Summer 2017 - 49
Canadian Dam Association Bulletin - Summer 2017 - CDA Developing New Ways to Distribute Guidelines
Canadian Dam Association Bulletin - Summer 2017 - 51
Canadian Dam Association Bulletin - Summer 2017 - 52
Canadian Dam Association Bulletin - Summer 2017 - Notice of Annual General Meeting
Canadian Dam Association Bulletin - Summer 2017 - Time to Renew Your Membership
Canadian Dam Association Bulletin - Summer 2017 - Buyers' Guide and Trade List
Canadian Dam Association Bulletin - Summer 2017 - 56
Canadian Dam Association Bulletin - Summer 2017 - 57
Canadian Dam Association Bulletin - Summer 2017 - 58
Canadian Dam Association Bulletin - Summer 2017 - 59
Canadian Dam Association Bulletin - Summer 2017 - 60
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