Learn about how you can be better prepared for flooding from industry professionals. Visit their booths for resources, advice and more! - Slide 1 ...
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Slide 1
Learn about how you can
be better prepared for
flooding from industry
professionals. Visit their
booths for resources,
advice and more!
Toronto and Region Conservation Authority 1
Slide 2
Flood Risk in the Dixie-Dundas Area
Presented by TRCA and the City of Mississauga
March 2, 2020
Slide 3
Presentation Outline
• Understanding potential flooding in Mississauga
• How are flood risks managed
• Mississauga's mitigation projects
• What can you do now,
from the City's emergency management office
• TRCA's flood management resources
The information contained in this presentation is copyright © Toronto and Region Conservation Authority
Toronto and Region Conservation Authority 3
Slide 4
Toronto and Region Conservation Authority 4
Flooding has been a concern for residents of the Toronto area since the area was first settled.
On October 15 and 16, 1954, Toronto received 210 mm of rain in a 12-hour period. For our
region, Hurricane Hazel remains the most severe flood in recorded history. Recognizing the
importance of flood management, the Provincial government amended the Conservation
Authorities Act to enable an Authority to acquire lands for recreation and conservation
purposes.
Slide 5
How are floodplain and flood risk maps
made?
Models of real (and
Hypothetical Storms Existing topography
planned) land-cover
This Photo by Unknown Author is licensed under CC BY-NC
Toronto and Region Conservation Authority 5
How are flood maps made?
TRCA must ensure that if development occurs in areas that are likely to experience flooding and
erosion that it is properly permitted in order to decrease the risk of loss of life, personal injury
and property damage.
Building in a floodplain can have major consequences and can also affect neighboring
properties by changing the physical characteristics of the valley or flood plain, or drainage to
these properties.
Developing flood plain maps requires detailed river and floodplain information and a lot of
science and engineering.
The maps are created based on canned scenarios to help engineers understand the worst-case
scenario for development and planning purposes. Flood maps are not necessarily based on
floods experienced in the past.
Slide 6
Flood Protection near Dixie-Dundas
The Dixie-Dundas
Channel and Dyke
work together to
provide flood
protection to the
City of Mississauga,
specifically to the
Dixie-Dundas
neighbourhood, by
reducing peak flows
during flood events.
Toronto and Region Conservation Authority 6
Slide 7
Toronto and Region Conservation Authority 7
The Dixie-Dundas cluster is subject to flooding due to a combination of capacity constraints in
the river channel and backwater from multiple culvert crossings.
Located on Little Etobicoke Creek, this cluster is near the intersection of Dixie Road and Dundas
Street East in the city of Mississauga. It is a provincially designated Special Policy Area (SPA).
The urbanized nature of the Little Etobicoke Creek watershed makes this cluster susceptible to
flooding from intense summer thunderstorms.
Significant flooding occurred during the July 8, 2013 storm when flows overtopped the
engineered channel and began flowing south along Queen Frederica Drive.
Slide 8
Flooding can happen any time of year
Summer Fall
• Thunderstorms with • Seasonal weather systems
significant rainfall – within – large wet weather such as
a short period of time, tropical storms, can last
intense localized several days. Prolonged
downpours from and heavy precipitation on
thunderstorms can produce top of already saturated
flash flooding. soils causes rivers to rise.
Spring Winter
• Spring freshet – • Ice jams – when a rise in
accumulation of snow water level or a thaw in the
during the winter season ice breaks into large
can lead to flooding during chunks, these chunks can
the early spring, if become jammed at bridges
conditions are right. When or other obstructions. The
temperatures rise, snow rise will become backed up
melts and turns to runoff. and can
Toronto and Region overflow
Conservation its banks.
Authority 8
Slide 9
Cities & Conservation Authorities Work Together
Conservation Authorities
• Monitor watershed and weather conditions and operate a flood
forecasting and warning system
• Issue Flood Messages
• Operate Conservation Authority dams and flood control structures
• Provide technical advice to municipalities
• Maintain communications with municipalities and other agencies
Municipal Role
• Notify appropriate municipal officials, departments and agencies.
• Determine the appropriate response and deploy municipal resources
to protect life and property.
• If required, declare a flood emergency and implement their
emergency response plan.
• Request provincial assistance if needed
Toronto and Region Conservation Authority 9
Slide 10
Not all flooding comes from a river…
Private drainage and surface water
Contact your insurance representative for any
property related damage due to flooding. Make
Sanitary sewer back up services sure your policy covers all types of flooding.
Most backups occur when the sewer pipe that runs from
your home to the Region’s main sanitary sewer
pipe is blocked with items such as roots or Residents near watercourses
grease. A blockage in the sewer pipe may Properties and structures located within a
cause wastewater to back up into your floodplain are especially susceptible to flooding
basement from the floor drain. due to the rise in water levels resulting from
large, infrequent storm events.
Overland Flow/urban flooding
Heavy downpour can cause storm drainage
systems to overflow. Water may spill onto
the property and enter the building
through the basement windows
or other openings.
Free Images fromhttps://pixabay.com/
Catch Basin also known as a storm drain inlet or curb inlet at street level where storm water enters the catch basin.Slide 11
Environmental Services
Greg Frew, P.Eng.
Acting Manager of Stormwater Projects &
Approvals, Environmental ServicesSlide 12
Types of flooding
Riverine (fluvial) flooding occurs when
water levels in a river rise and overflow its
banks, spilling onto adjacent lands.
Conservation Authorities identify riverine
flood risks
Urban (pluvial) flooding occurs when a
© Reuters/Andy Clark
heavy rainfall event exceeds the capacity
of the storm sewer system, causing the
water to pond within the roadway. Urban
storm infrastructure is the responsibility of
municipalities.
Important Difference: Urban flooding can
occur anywhere, independent of a water
© Todd Yates body
12Slide 13
Urban Storm Drainage System
Storm sewers (minor system) – drain storm runoff
from most everyday storms up to the 10-year storm
(1 in 10 chance that it will occur in a given year).
Roadways (major system) – store and drain
excess runoff when the storm sewer capacity is
exceeded during major storm events.
Important: Temporary ponding is expected during
these major storm events.
13Slide 14
Looking for Solutions:
City of Mississauga Flood
Studies
14Slide 15
1. Dixie-Dundas Flood Mitigation Study
Objective: review options to reduce or eliminate
the spill of riverine floodwaters from Little Etobicoke
Creek near Dixie-Dundas
Timing:
• Phase 1 Feasibility –2019/20
• Phase 2 Municipal Environmental Assessment
Study – 2020/2021
• Upcoming Open House #1- Late spring 2020
Flood spill from Little Etobicoke Creek
15 15Slide 16
2. Little Etobicoke Creek Flood Evaluation Study
Objective: review options to reduce the impacts
of urban flooding in the Little Etobicoke Creek
watershed
Underground stormwater storage galleries Timing:
• Phase 1 Define flood risks – 2017/2018
• Phase 2 Assessment of flood reduction
solutions – 2019/2020
Storm sewer improvement works
• Upcoming Open House #2 – late spring 2020
16 16Slide 17
Flood Preparedness
Ben Gallagher
(A) Emergency Management Specialist
Office of Emergency ManagementSlide 18
Flood Preparedness
There are actions you can take to reduce the risk of flooding, including:
• Wastewater back-up flooding
• Install sanitary wastewater backflow preventer valve
• Disconnect roof downspouts from wastewater lateral pipe
• Storm Sewer back-up flooding
• Improve lot grading
• Clean leaves and other debris from eaves troughs
• Do not pour or flush items into drains or toilets that can cause blockages (grease, fats, oil,
wipes)
Some insurance companies offer overland flooding insurance. Contact your insurance
broker to see whether this is available in your area.
Please visit the Office of Emergency Management table for more information on
flooding preparedness and recovery
18Slide 19
Insurance Tips
It is recommended to:
• Have homeowners or tenants
insurance
• Be familiar with your policy coverage
• Know the 24/7 contact number to
start a claim
• Inventory your belongings
19Slide 20
General Emergency Preparedness
Households are expected to be able to cope on their own for 72 hours
(3 days) during emergencies.
You can prepare yourself and family by following the three steps to
emergency preparedness:
1. Make a Plan
2. Build a Kit
3. Stay Informed
20Slide 21
General Emergency Preparedness
More information on emergency preparedness:
City of Mississauga
http://www.mississauga.ca
A digital handbook with information
Region of Peel specific to Mississauga was created
https://www.peelregion.ca to help you understand and prepare
for flooding: trca.ca/flood-risk-
Emergency Management Ontario dixie-dundas
https://www.ontario.ca/emo
Public Safety Canada
https://www.getprepared.gc.ca
21Slide 22
Who to call during a flood?
• If you are in danger or there is a threat to life and safety, call 911 immediately.
• If you see any potential damage to your property, call your insurance representative as
soon as possible.
• For hydro-related questions, contact Alectra Customer Service at 1-877-963-6900
(Press 2).
• To report localized flooding on municipal roads, blocked catch basins or municipal
infrastructure, contact the City of Mississauga by dialing 3-1-1 (outside city limits: 905-
615-4311) or by emailing public.info@mississauga.ca.
• To report river flooding from the Etobicoke Creek, leave a voicemail on the TRCA floodline
at 416-661-6514. A flood duty officer will return your call.
Toronto and Region Conservation Authority 22Slide 23
Sign up for Flood Messages
For important Mississauga updates, follow @CityMississauga
Toronto and Region Conservation Authority 23Slide 24
2
4
Site specific
response planning
TRCA and the City of Mississauga work
together on emergency planning, and the
information we have from our modelling
is used to inform contingency plans
Toronto and Region Conservation AuthoritySlide 25
Continued Flood Monitoring
TRCA has a network of real-time river and rain gauges across the GTA to:
• Monitor the water levels in specific stream and behind dams
• Measure how much precipitation has fallen
beta.trcagauging.ca
Nearby Stream & rain gauges
Stream Gauge:
• HY098 - Little Etobicoke
Precipitation Gauge:
• HY099 – RathwoodSlide 26
Thank you
Information presented today can be accessed online at:
trca.ca/flood-risk-flood-dixie-dundas
www.trca.ca/flood
@TRCA_Flood
Toronto and Region Conservation Authority 26You can also read
