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V05
Prepared for The City of Calgary by:
Contact:
Flood Risk and Resilience in Calgary/BownessPresentation to the Bowness Community Association Flood Mitigation Working Group
June 17, 2019
1
Sandy Davis, P.Eng.
Planning Engineer, River Engineering
Flood Risk Awareness Program Manager
The City of Calgary
Water Services
ISC: Unrestricted
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Objectives of presentation:
1. Flood risk in Calgary and Bowness
2. The City’s Flood Resilience Plan
3. How the Bowness Barrier project fits it
4. Flood preparedness:
• How The City prepares for floods
• How residents can prepare
2
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Understanding our River Flood Risk
• Risk factors:
• Rainfall
• Snowpack
• Seasonal temperatures
• Highest flood risk May 15 to July 15
• 12 to 24 hour warning
3
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Past River Flood Events in Calgary
1897
1915
2013
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5
Naturalized Flood Probabilities in Bowness
(Without mitigation)
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Expert Management Panel on
River Flood Mitigation (2014)
Resilience is complex.
• Issue is bigger than Calgary
• City and Province coordinate
• Structural and non-structural
• Local and regional
In 2015-17 studied costs and
benefits of the best combination
of options.
River Flood Resilience Strategy Development
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Without mitigation flooding over the next 100 years cause damage of:
$168M/year (“average annual damages”)
or over $16B of total losses
Work since 2013 reduces risk to:
$115M/year (“average annual damages”)
or over $11B of total losses
The potential flood damages in Bowness are $11M/year.
Of these, about 22% are from groundwater.
Flood risk and mitigation to date
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Estimated Potential Damages in Bowness
Flood risk and mitigation to date
Flood Event 1:10 1:20 1:35 1:50 1:75 1:100 1:200
Total Damages in
Bowness ($M)$16 $94 $140 $163 $174 $189 $221
Groundwater
Damages as
Percentage of
Total Damages
37% 33% 20% 13% <10% <10% <10%
Source: IBI (2017), Flood Mitigation Options Assessment
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New community flood barriers
& local improvements
New reservoirs
upstream
New operational
efficiencies
Improved forecasting/emergency
responseNew property –level programs
Update land use policy &
development
9
Key mitigation measures studied / combined
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Calgary’s Flood Resilience Plan
Future Bow
reservoir (watershed management
potential)
Springbank
Off-stream
Reservoir
Enhanced
TransAlta
operations
Glenmore
Dam gate
upgrades
Community flood barriers on
the Bow River
Property protection
and floodplain policy
Emergency
response
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Elbow River
Springbank Reservoir
+ new Glenmore gates
11
Glenmore gates
Bow River
New upstream reservoir (BRWG)
+ TransAlta agreement
+ Local barriers
+ Gravel bars
+ Land use policy and building regulations
+ Education and awareness
+ Emergency preparedness, response, forecasting
Bow Reservoir Barriers
River Flood Management Plan for Calgary
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What We Have Done Since 2013
12
Flood Mitigation Underway/Complete
SpringbankOff-Stream Reservoir
Remaining Risk
• Glenmore Dam gates
• Flood barriers
• River bank strengthening
• Stormwater gates
• Lift stations
• Bridge replacements
• Riparian restoration
• Bow upstream reservoir
• Enhanced Operations
with TransAlta
• Complementary barriers
• Emergency Response
Calgary River Flood Risk
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• Agreement put in place for
2016 - 2021
• Sets reservoir levels and
operations during flood season,
to maximize potential flood
mitigation
• Major benefit for small and
intermediate size floods
• Significant benefit in Calgary
• Discussions underway between
GoA and TransAlta to extend
and expand agreement
TransAlta Ghost
Dam and Reservoir
Government of Alberta and TransAlta operations
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New Upstream Reservoir on the Bow River
• The City continues to
advocate that a new Bow
River reservoir is necessary
to manage flooding in
Calgary
• The Province is doing a
feasibility study (2018-2019)
for a new reservoir locations
on the Bow River upstream
of Calgary.
• With Provincial funding,
TransAlta is investigating
how quickly Ghost Reservoir
can be lowered, to improve
potential flood mitigation
Source: YYCMatters Survey 2019 April 3
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Key report recommendations
15
Extend/expand 2016 TransAlta operational agreement
Enhancements to overall TransAlta operations
One of the following major infrastructure projects:
New
Glenbow
Reservoir
New
Morley
Reservoir
Expand
Ghost
Reservoir
and
and
OR OR
Bow River Water Management Project
(Bow River Working Group)
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Status of key BRWG recommendations
16
Study major infrastructure options
Province committed to conceptual assessment of 3 most promising options. Work underway.
Study minor infrastructure project
Province committed to study increase the drawdown rate in the Ghost Reservoir with TransAlta. Work underway.
Extend and expand TransAlta Operational Agreement
Discussions between Province and TransAlta underway.
A renewed Bow River Working Group process is needed to move from conceptual studies to implementation
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Community-level mitigation
17
• Includes combination of infrastructure (ex. barriers), land use
policy, property level mitigation, and emergency response
• Community mitigation alone cannot mitigate 2013-level flood
effectively
• Communities requiring proposed barriers: Bowness,
Sunnyside, Inglewood via Pearce Estate Park, Downtown
• Diverging views on community mitigation
• Different community situations and risks
• Unique situations within overall flood resilience plan
• Outcomes must align with The City’s flood resilience plan
• City-wide and individual project considerations
• Ex. Barriers enhance TransAlta mitigation benefitsMay 15, 2019 UCS2019-0653
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Why consider local barriers?
18
• Upstream mitigation alone is not enough
• Barriers benefit communities with or without a new dam
• Improve the usefulness of upstream mitigation
• Protect community from most frequent/most likely floods (reduced
losses and community disruption)
• Can be built and start providing protection before a new reservoir can,
or before land use changes can be phased in
• Within Calgary’s control
• Cost effective – at appropriate scale
• Protection increases once new reservoir is built
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April 30, 2018 | Presentation to School of City Planning, University of Alberta
West Eau Claire Park / Eau Claire Public Realm
engage.calgary.ca/eauclaire
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Centre Street Lower Deck Barrier
• Stop-log barrier that can be
deployed in advance of a flood
event
• Increases resiliency from ~1:75
to 1:200 year
• Protects the community of
Chinatown and Riverfront Ave.
• Completed 2018
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Bowness
21
• Proposed flood barrier
• Requires construction on river front owners’
properties
– Riverfront owners have concerns regarding barrier
• Proposed barrier provides flood mitigation for 350
properties
– Includes non-riverfront properties
• Options will be discussed as part of community
engagement
May 15, 2019
Study considerations
Community flood risks City-wide flood risks
Social/environmental impacts Need for investments in other
communities
Budget/external funding Upstream mitigation
Public value for money Flood policy/land use changes
Emergency response/evacuation Recovery costs
UCS2019-0653
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Policy and Mapping
• Provincial flood mapping
• City in contact with Province on release of updated maps
• No date set for release
• Implications on City land use policy and planning
• Uncertainty regarding provincial floodplain development
regulations
• Policy Review – starting in 2019
• Assessing flood, land use and development policies
• Identifying flood policy gaps
• Integrating with Municipal Development Plan review and
Land Use Bylaw review work
22
May 15, 2019 UCS2019-0653
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Policy and Mapping –
Current Flood Hazard Area Map
23
May 15, 2019 UCS2019-0653
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UCS2018-0600
2013 FLOOD ACTUAL
(City and TransAlta operations,
emergency response)
2013 flood with full flood
management plan in place
(New upstream reservoirs, enhanced
operations, community barriers,
emergency response)
2013 flood unmitigated
(what would have happened if
no action was taken)
River Flood Management Plan
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Federal
Provincial
Citizens
Municipal
25
Resiliency by integrated levels of flood
mitigation
Watershed
Community
Property
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How Does The City Prepare?
26
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• Year-round forecasting and
monitoring
• 24/7 monitoring May to July
(weather and river
flows) – already underway for 2019
• Increased team capacity and
training
• Share modelling and forecast
information with CEMA and
Government of Alberta
Flood Preparedness:
Forecasting
Calgary
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Flood Preparedness:
Infrastructure and Response
28
• Reservoirs are lowered
• Field Readiness – test valves, pre-position pumps and
other emergency supplies
• Training and Exercises – Water maintains a team of
140 members trained in ICS
• Annual updates to Flood Emergency Reference
Manual
• In 2018 expanded response plan to include resources
and staff from other departments
• On Bow River, the Water Emergency Operations
Centre may be activated when flow reaches 400 m3/s.
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How Can Citizens Prepare?
18/04/201
6
29
Know Your Risk.
Be Prepared.
Stay Informed.
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Know Your Risk.
• River flooding impacts all Calgarians – whether you live, work,
commute or recreate in the city centre, or along the Bow or Elbow
Rivers.
• Know Your Risk: check maps at calgary.ca/floodinfo
30
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• Prepare your home or business
• Move valuables, electronics and documents to a
high/safe place (not in basement)
• Finish basements with easy-clean materials
• Have an evacuation plan:
• Know what to take with you (medication,
documents)
• Know where you will go
• Have a plan to communicate with your loved ones
• Follow directions during a flood
• Not following directions could put you, your loved
ones, and emergency responders at risk
• Read the Flood Readiness Guide for more tips
• calgary.ca/floodinfo
31
Be Prepared.
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Stay informed.
Flooding occurs quickly and with little warning.
Stay up to date on conditions and be prepared to act.
32
Links and information at
calgary.ca/floodinfo
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2019 Flood Readiness Campaign:
Keeping Citizens Informed
• Flood E-Newsletter
• Disaster Alley booth
• Walking tours (Eau Claire)
• ENMAX insert (June)
• Report to Calgarians (May)
• Launch of flood story map
• Updates to website
• Social Media posts & ads
• Community presentations
• Media coverage
8
Information and Sign-up at
calgary.ca/floodinfo
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Be Prepared. Stay Informed.
Sign up for our e-newsletter
www.calgary.ca/floodinfo
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Supplementary Slides
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What are we talking about?
• What is a “1 in 100 year flood”?
• A flood event that has a 1% chance of occurring in any
given year
Flood Event Chance of Occurrance
1:10 year 10%
1:20 year 5%
1:50 year 2%
1:100 year 1%
1:200 year 0.5%
V052019-06-
17Presentation 37
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 20 40 60 80 100
Pro
bab
ilit
y o
f at
Least
On
e O
ccu
rran
ce (
%)
Design Life or Time Span (Years)
Hydrologic Risk
1:2 Year Flood
1:5 Year Flood
1:10 Year Flood
1:25 Year Flood
1:50 Year Flood
1:75 Year Flood
1:100 Year Flood
1:200 Year Flood
1:350 Year Flood
Risk of At Least One Occurrence of the Specified Flood within the Design Life Span
Design
Life
(Years)
Return Period (Years)
2 5 10 25 50 75 100 200 350
1 50% 20% 10% 4% 2% 1.3% 1.0% 0.5% 0.3%
2 75% 36% 19% 8% 4% 2.6% 2.0% 1.0% 0.6%
5 97% 67% 41% 18% 10% 6% 5% 2.5% 1.4%
10 100% 89% 65% 34% 18% 13% 10% 5% 3%
25 100% 100% 93% 64% 40% 29% 22% 12% 7%
50 100% 100% 99% 87% 64% 49% 39% 22% 13%
75 100% 100% 100% 95% 78% 63% 53% 31% 19%
100 100% 100% 100% 98% 87% 74% 63% 39% 25%
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Past River Flood Events in Calgary
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39
Flooding in Bowness – June 22, 2013
(flow in Bowness (1840 m3/s, ~1:70
naturalized flood)
Note: Aerial photo taken
after flood peak
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Elbow River mitigation
40
Springbank Reservoir (SR1):
• Will mitigate approximately 80% of flood
risk on Elbow River once completed
• Environmental Impact Assessment
requirement ongoing
• 2019 January 30: 465 acres of land
acquired by the Province (20 per cent)
• 2019 March 13: $168M announced by
Infrastructure Canada
Glenmore dam upgrades:
• Estimated completion: spring 2020
• With SR1, will mitigate to at least a
2013-level flood event
• Supported with ACRP fundingMay 15, 2019
Springbank
Reservoir
UCS2019-0653
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2016 City-wide Flood Mitigation Engagement
41
May 15, 2019 UCS2019-0653