Saskatchewan Flood and Natural Hazard Risk Assessment

2018 Stakeholder Insights Saskatchewan Flood and Natural Hazard Risk Assessment Prepared for Saskatchewan Ministry of Government Relations By V. Wittrock1, R.A. Halliday2, D.R. Corkal3, M. Johnston1, E. Wheaton4, J. Lettvenuk1, I. Stewart3, B. Bonsal5 and M. Geremia3 SRC Publication No. 14113-2E18 May 2018 Revised Dec 2018 EWheaton Consulting Cover Photos: Flooded road – Government of Saskatchewan Forest fire – Government of Saskatchewan Winter drought – V.Wittrock January 2009 Snow banks along roadway – J.Wheaton March 2013 Oil well surrounded by water – I. Radchenko May 2015 Participants at Stakeholder Meetings – D.Corkal June 2017 Kneeling farmer on cracked soil – istock photo Tornado by Last Mountain Lake – D.Sherratt Summer 2016 This report was prepared by the Saskatchewan Research Council (SRC) for the sole benefit and internal use of Ministry of Government Relations. Neither SRC, nor any of its employees, agents or representatives, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, reliability, suitability or usefulness of any information disclosed herein, or represents that the report’s use will not infringe privately owned rights. SRC accepts no liability to any party for any loss or damage arising as a result of the use of or reliance upon this report, including, without limitation, punitive damages, lost profits or other indirect or consequential damages. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favouring by SRC Saskatchewan Flood and Natural Hazard Risk Assessment Prepared for Saskatchewan Ministry of Government Relations By V. Wittrock1, R.A. Halliday2, D.R. Corkal3, M. Johnston1, E. Wheaton4, J. Lettvenuk1, I. Stewart3 B. Bonsal5 and M. Geremia3 1 Saskatchewan Research Council 2 R. Halliday & Associates 3 Walker Projects Consulting Engineers 4 EWheaton Consulting 5 Environment and Climate Change Canada SRC Publication No. 14113-2E18 May 2018 Revised October 2018 . “The people of this province [Saskatchewan] have the right attitude and demeanour to endure these hardships [natural hazards] and improve upon them. They need good vision and science to help them make the best decisions” (Anonymous Stakeholder in Corkal 2018). SK Flood & Natural Hazard Risk Assessment 2018 EXECUTIVE SUMMARY Natural hazards and associated extreme events are key determinants of the character of many natural and human-influenced systems. Historically, Saskatchewan has been affected by various natural hazards including droughts, wildfires and floods. The effects of these events have influenced various facets of Saskatchewan’s society (e.g., urban, rural, First Nations communities). At times, the natural hazards pose severe economic impacts to Saskatchewan and Canada. For example, the 2001–2002 drought caused an estimated $5.8 billion drop in Canada’s gross domestic product, with the most significant impacts being to the Prairie provinces. In Saskatchewan, the drought of 2001–2002 resulted in an estimated reduced agricultural production of more than $1.6 billion. The Saskatchewan forest fires of 2015 cost more than $100 million with 1.7 million hectares burned and over 10,000 people evacuated from northern communities. Floods are a common occurrence in Canada, including Saskatchewan, and constitute the largest accumulated payout of federal disaster assistance. The Provincial Disaster Assistance Program expended more than $300 million in calendar years 2010 to 2014, with 2011 expenditures greater than $150 million. Most of these expenditures were flood-related. Multi-year wet or multi-year dry periods are part of Saskatchewan’s natural climate and hydrological characteristics. Recent research for Saskatchewan has determined that natural hydrologic variability is greater than indicated by the instrumental record. When climate change impacts are considered, it is estimated that even greater future climate variability will occur, with increasing risks from droughts, storms and floods and potentially fires. The wider range of variability of natural hazards and associated risks to Saskatchewan must be considered for the province to strengthen its resilience and reduce risks to the economy, social well-being and the environment. As the Province of Saskatchewan moves to a more proactive risk management strategy for dealing with natural hazards, an important step is to determine the province’s vulnerability to various natural hazards. By learning from the past and considering future vulnerability to climate change, the province can determine feasible mitigative responses and initiatives to reduce future risk. The team that undertook this project, Saskatchewan’s Flood and Natural Hazard Risk Assessment developed a standardized risk assessment that was utilized with all the selected natural hazards. This approach was undertaken to help inform and prioritize longer and shorter-term risk reduction strategies. Selected natural hazards that pose a threat to Saskatchewan industry, the general public and governments at all levels were included in the analysis. The natural hazards selected for analysis were flooding (mountain runoff, plains runoff, lake, overland and groundwater), drought (agricultural, hydrologic, meteorological and socio-economic), forest fires (human caused close to communities), grass fires (greater than 1,000 hectares), summer convective storms (tornadoes, high winds, heavy rain, hail), winter storms (freezing rain, high winds, snow, blizzard conditions) and earthquakes. These natural hazards have already been experienced and have the potential of occurring under future climate conditions. The risks of each of the selected natural hazards were assessed individually using two types of approaches. The first utilized a plausible worst-case scenario that incorporated historic events, that SRC Publication No. 14113-2E18 i 2018 SK Flood & Natural Hazard Risk Assessment typically resulted in having occurred at some point in the last 100 years, but was adapted to present- day situations. The second scenario added a layer of climate change to the plausible worst-case scenario focused on the modeled climate of the 2050s. Each of the natural hazards tends to impact different regions of the province. Natural hazards such as drought, overland flooding, forest fires and winter storms can affect both localized and extensive geographic regions. Others like plains runoff flooding, lake flooding, convective summer storms, mountain runoff flooding and grass fires are generally relatively localized in geographic exposure. Groundwater flooding and earthquakes are highly localized. In addition, each of these natural hazards can occur over varying time frames. For example, drought can last many years while severe convective summer storms take place in a matter of hours or less. Antecedent conditions are critical in determining the severity of the natural hazard. Linkages also occur among many of the natural hazards and if one is occurring or has occurred, another natural hazard may happen as the result of the first one. For example, all forms of flooding can be heavily influenced by both winter and summer storms, and flooding could be considered a secondary impact to these storm events. Similarly, drought conditions can lead to an increase in the occurrence and severity of grass fires and possibly northern forest fires. The first scenario examined the plausible worst-case natural hazards. Most of these have occurred at some point in the last 100 years. The likelihood of present-day occurrence can range from almost certain to rare A good estimate of present-day consequences of the plausible worst-case scenario for each hazard is applied based on these historic events. The level of impacts resulting from these various hazards ranges from insignificant to catastrophic depending on the impact category of the natural hazard. An aggregate risk level for each natural hazard is estimated for each of the natural hazards based on these impacts and the likelihood of occurrence (Table A and Figure A). ii SRC Publication No. 14113-2E18 SK Flood & Natural Hazard Risk Assessment 2018 Table A Comparison of Plausible Worst-Case Natural Hazard Scenarios Impact Categories Natural Likelihood of Human Aggregate Case Study Location Public Hazard Occurrence Health & Social Economic Environment Risk Administration Safety Mountain Moderate to Low to Runoff Prince Albert Rare Moderate Minor Minor Minor Major Moderate Flooding Plains Runoff Minor to Regina Unlikely Moderate Major Major Moderate Moderate Flooding Moderate Fishing Lakes Moderate to Lake Flooding Unlikely Moderate Minor Minor Minor Moderate Last Mountain Lake Major Overland Agricultural region of Minor to Unlikely Minor Minor Major Moderate Moderate Flooding Saskatchewan Moderate Groundwater Insignificant Insignificant Insignificant to Insignificant Insignificant Highly localized Unlikely Low Flooding to Minor to Minor Minor to Minor to Minor Drought – All Agricultural region of Major to Major to Moderate to Unlikely Catastrophic Catastrophic High Types Saskatchewan Catastrophic Catastrophic Major Human-caused forest fires close to Moderate to Minor to Moderate Forest Fire Unlikely Major Major Moderate communities; forested Major Moderate to High zone of province Grass fire > 1,000 ha; Moderate to Minor to Grass Fire agricultural region of Unlikely Major Minor Minor Moderate Major Moderate

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