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

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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

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Past River Flood Events in Calgary

1897

1915

2013

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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

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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

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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

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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

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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

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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

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• 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?

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• 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

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• 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

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May 15, 2019 UCS2019-0653

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Policy and Mapping –

Current Flood Hazard Area Map

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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

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Resiliency by integrated levels of flood

mitigation

Watershed

Community

Property

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How Does The City Prepare?

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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

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• 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

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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

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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

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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.

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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

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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

Sandra.Davis@Calgary.ca

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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%

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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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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

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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

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May 15, 2019 UCS2019-0653