Flood Risk Management Flood Forecasting and Warning Program and Flood Risk Management Projects Presented by: Rebecca Elliott, P.Eng Flood Risk Management Engineer Friday Forum January 25, 2019 Presentation Outline • History of TRCA • Flooding 101 • Flood Forecasting and Warning Program • Flood Risk Management Projects • Flood Risk Assessment and Ranking Project • Toronto Islands Characterization and Risk Assessment • Works Influenced by the Flood Characterization Project (Next Steps) • Recommendations The information contained in this presentation is copyright © Toronto and Region Conservation Authority Toronto and Region Conservation Authority 2 HISTORY OF TRCA Toronto and Region Conservation Authority 3 About the TRCA • Conservation Authorities were established in 1946 under the Conservation Authorities Act “To ensure the conservation, restoration and responsible management of hydrological features through programs that balance human, environmental and economic needs.” • Several smaller CA’s made up what is now known as Toronto and Region Conservation Authority • Then in October of 1954 everything changed….. Toronto and Region Conservation Authority 4 Hurricane Hazel: October 15-16, 1954 Toronto and Region Conservation Authority 5 Hurricane Hazel Toronto and Region Conservation Authority 6 History of Flood Control • Metropolitan Toronto and Region Conservation Authority (MTRCA) was formed in 1957. • Amendment to CA Act to acquire lands for recreation and conservation purposes • 1959 Plan for Flood Control and Water Conservation 1. Property acquisition 2. Control structures: dams and channels – move the water quickly 3. Land use planning Toronto and Region Conservation Authority 7 1. Property Acquisition Toronto and Region Conservation Authority 8 Map of TRCA Greenspaces Toronto and Region Conservation Authority 9 2. Flood Control Infrastructure Toronto and Region Conservation Authority 10 TRCA Flood Control Infrastructure Today Toronto and Region Conservation Authority 11 Flood Control Infrastructure - Dams Claireville Dam, Brampton G.Ross Lord Dam, Toronto Toronto and Region Conservation Authority 12 Flood Control Infrastructure - Channels • Built to quickly convey floodwaters away from a risk area • Results in ‘flashy’ watersheds • Can sometimes exacerbate the situation downstream because of loss of stream length and storage • Negative ecological impacts Toronto and Region Conservation Authority 13 3. Land Use Planning Living City Policies for Planning and Development in the watersheds of the Toronto and Region Conservation Authority Toronto and Region Conservation Authority 14 WATERSHEDS Toronto and Region Conservation Authority 15 TRCA’s Jurisdiction and Watersheds When rain falls on our watersheds, that water makes its way into our local rivers and streams, which drain to Lake Ontario Toronto and Region Conservation Authority 16 Flashy Watersheds Toronto: • so flashy, little lead time Calgary: • much larger drainage area, 12 hour lead times Toronto and Region Conservation Authority 17 FLOODING 101 Toronto and Region Conservation Authority 18 Floods Happen….often Toronto and Region Conservation Authority 19 What is Flooding? Toronto and Region Conservation Authority 21 Types of Flooding - Riverine Riverine flooding: the partial or complete inundation of the floodplain, caused by bank overtopping when the conveyance capacity of rivers and streams is exceeded Toronto and Region Conservation Authority 22 Types of Flooding - Urban Urban flooding: the inundation of a built environment, caused by rainfall overwhelming the capacity of drainage systems, such as storm sewers and roads. Toronto and Region Conservation Authority 23 Riverine and Urban Flooding Riverine Flooding falls under the Urban flooding is the responsibility of mandate of Conservation Authorities. municipalities. Toronto and Region Conservation Authority 24 What Causes Flooding? Toronto and Region Conservation Authority 25 Why is it getting worse? 1. Climate Change 2. Land use changes 3. Increased Exposure to Risk Toronto and Region Conservation Authority 26 Who Deals with Floods? Municipalities Deal with all major emergencies and are responsible for the welfare of their residents Ministry of Natural Resources and Conservation Authorities Forestry (MNRF), on behalf of the Operating a province forecasting and May coordinate a response warning system in support of municipal action. Toronto and Region Conservation Authority 27 Municipality Role & Responsibilities 1. Notify appropriate municipal officials, departments and agencies in accordance with their municipal emergency plan. 2. Determine the appropriate response to a flood threat and, if warranted, deploy municipal resources to protect life and property. 3. If required, declare a flood emergency and implement their emergency response plan. 4. Request provincial assistance under the Emergency Management and Civil Protection Act, if municipal resources are inadequate to respond to the emergency. 5. Maintain liaison with Conservation Authority Flood Duty Officers. Toronto and Region Conservation Authority 28 Provincial Role 1. Operate and maintain a provincial forecasting and warning system to alert MNRF District Offices and Conservation Authorities of potential meteorological events that could create a flood hazard. 2. Maintain communications with MNRF District Offices and Conservation Authorities regarding the status of provincial flood potential. 3. Receive messages from CAs, MNRF Districts and other agencies and provide analysis and information that is used to guide the MNRF’s response to a flood. 4. Assists the MNRF Districts where CAs do not exist in the preparation of river response forecasts, daily planning cycle, and the monitoring of local storm conditions. Toronto and Region Conservation Authority 29 Individuals and Homeowners 1. Make an emergency plan with loved ones 2. Make an emergency kit or To-Go-Bag 3. Understand your risks 4. Prepare for these risks 5. Reduce likelihood of flood damage 6. Follow directions of local emergency responders Toronto and Region Conservation Authority 30 Conservation Authorities Role: Flood Forecasting and Warning Program • Monitor watershed and weather conditions and operate a flood forecasting system • Issue Flood Messages • Operate Conservation Authority dams and flood control structures • Provide advice to municipalities • Maintain communications with municipalities and other agencies Toronto and Region Conservation Authority 31 Monitoring Network • Rainfall and water level data is collected throughout TRCA and is transmitted in real-time • Stream water level • Precipitation amounts • Reservoir water levels LOCATION / York Peel City of Durham TOTAL GAUGE TYPE Region Region Toronto Region Stream Gauges 0 5 8 1 14 Rain Gauges 9 6 5 1 21 Reservoir Gauges 2 1 1 0 4 TOTAL 11 12 14 2 39 Toronto and Region Conservation Authority 32 Monitoring Network Toronto and Region Conservation Authority 33 TRCA’s Flood Monitoring Website www.trcagauging.ca Toronto and Region Conservation Authority 34 TRCA Flood Message Types No flood conditions exist High flows, unsafe banks, melting ice or other factors that could be dangerous for recreational users such as anglers, canoeists, hikers, children, pets, etc. Flooding is not expected. Early notice of the potential for flooding based on weather forecasts calling for heavy rain, snow melt, high wind or other conditions that could lead to high runoff, cause ice jams, lakeshore flooding or erosion. Flooding is possible in specific watercourses or municipalities. Municipalities, emergency services and individual landowners in flood-prone areas should prepare. Flooding is imminent or already occurring in specific watercourses or municipalities. Toronto and Region Conservation Authority 35 TRCA Flood Messages @TRCA_Flood www.trca.ca/flood Toronto and Region Conservation Authority 36 When is “Flooding Season”? Toronto and Region Conservation Authority 37 Winter/Spring Flooding Winter: 1. Rain-on-snow event 2. Ice jams Spring: 1. Spring freshet 2. Spring showers Toronto and Region Conservation Authority 38 Summer Flooding – Convective Thunderstorms Two types of summer storms: 1. Large scale weather systems with short or long periods of rainfall 2. Short-lived thunderstorms with significant rainfall Toronto and Region Conservation Authority 39 August 7th, 2018 Toronto and Region Conservation Authority 40 August 7th, 2018 Hilldale Road Concrete Channel Toronto and Region Conservation Authority 41 August 7th, 2018 Very localized area received a dumping of rainfall ranging from 30mm to over 100mm in a span of 2.5 hours. Toronto and Region Conservation Authority 42 Fall Flooding - Hurricanes Toronto and Region Conservation Authority 43 Flood Risk Management Projects 1) Flood Risk Assessment and Ranking Project 2) Toronto Islands Characterization and Risk Assessment 3) Flood Remediation Studies 4) Outreach Program Toronto and Region Conservation Authority 44 LAKE ONTARIO FLOODING SITUATION 2017 Toronto and Region Conservation Authority 58 The Lead Up • Prior to April 2017 there was no record of any Shoreline Hazard warning message issuance. • Primary focus on Riverine Flooding Toronto and Region Conservation Authority 59 The Situation: Lake Ontario Flooding 2017 • First notice of high lake level issues in mid-April at the Ashbridges Bay beach volleyball courts Source: Toronto Star; Tues April 11, 2017 https://www.thestar.com/news/gta/2017/04/11/is-the-ashbridges-bay-beach- disappearing.html Toronto and Region Conservation Authority 60 TRCA