Building Resiliency in Great Lakes Communities
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Experiences drawn from the Great Lakes Coastal Flood Study, including identification of local flood hazards, strategy for communicating flood risks, and the development of a coastal mitigation action strategy to reduce and mitigate hazards. Presented by Jaspreet Randhawa, CFM and Laura Kelliher, CFM of CDM Smith at the Association of State Floodplain Managers (ASFPM) 2015 Conference.
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Building Resiliency in Great Lakes Communities
- 1. Building Resiliency in Great Lakes Communities June 03, 2015 Jaspreet Randhawa, CFM Laura Kelliher, CFM
- 2. Outline • Brief introduction to Great Lakes Coastal Flood Study • Identification of coastal flood hazards • Data sets useful for communicating coastal flooding risks • Coastal Mitigation Action Strategy intent • Overview of strategy • Activities in flight for implementation
- 3. What is being done to identify coastal flood hazards Compute Base Flood Elevations consisting of 4 basic components:1. Storm surge stillwater elevation (SWEL) – determined from storm surge model 2. Amount of wave setup 3. Wave height above storm surge (stillwater) elevation 4. Wave runup above storm surge elevation (where present)
- 4. Introduction to the Great Lakes Coastal Flood Study
- 5. Data sets useful for communicating coastal flooding risks • Work Maps – Indicate mapping in Effect (if in NFHL) and proposed map • Coastal Summary Report – Summary engineering information • Extremal total water level and Stillwater level analysis • Model and elevation data available upon request (10 GB or larger) • Risk MAP products
- 6. Data: Risk MAP Flood Risk Datasets • Changes Since Last FIRM (CSLF) • Coastal Depth Grids • Flood Risk Assessment (HAZUS) • Coastal Inundation
- 7. 7 Data: Changes Since Last FIRM SFHA Decrease Unchanged Unchanged SFHA Increase Unchanged SFHA Increase
- 8. Data: Coastal Depth Grid • Should reflect total depth (i.e. stillwater and waves) – typically only produced for the 1% annual chance flood • Created using the regulatory mapping and associated zone breaks as input
- 9. Data: Coastal Flood Risk Assessments • Uses coastal depth grids as input for the refined analysis • Hazus analysis and data can support adoption of higher regulatory standards • Provides justification to fund mitigation actions
- 10. Data: Areas Affected by Increased Coastal Inundation • Highlights areas that would be inundated if water levels increased • Typically created for the 1% annual chance flood, but could be done for other flood events • Possible causes for higher flood levels include : – More severe storm events – Climate change impacts such as sea level rise
- 11. Purpose and objective of the Coastal Mitigation Action Strategy Purpose – Natural hazard risk reduction strategy – Coordination with Great Lakes Stakeholders – Guidance to facilitate risk reduction discussions – Integrate data produced through the Risk MAP projects into existing coastal community planning and hazard mitigation activities Objectives – Public Awareness and Outreach – Hazard Mitigation Planning – Alignment and Synergies
- 12. Overview of strategy • Leverage Knowledge of Great Lakes Existing Data, Tools, Programs, and Local Priorities – Assess Great Lakes Discovery Information – Assess Great Lakes Consultation Stakeholder Information
- 13. Overview of strategy • Great Lakes Risk Reduction Support Toolkit – Great Lakes Mitigation Action Strategy Database – Great Lakes Mitigation Action Idea Database – Community Risk Reduction Engagement Plan Template • Develop Mitigation Action Ideas and Move Them Forward
- 14. Key items for implementation • Tiered community engagement approach • Develop Community engagement plan • Heavy stakeholder involvement • Develop certain datasets to facilitate risk reduction discussions – Individual community profiles – Hot spot maps – Risk MAP products • Community Action Advancement Summary Plan
- 15. Actions in flight for implementation – Current scope for strategy implementation – Development of unique risk communication tools • Profiles, hot spot maps – Considerations • Local stakeholders and champions • Unique shoreline characteristics • Land use near shoreline • Infrastructure
- 17. Example Profile
- 18. Common Coastal Features of Great Lakes
- 19. Common Coastal Features of Great Lakes
- 20. Common Coastal Features of Great Lakes
- 21. Impacts at Varying Lake Levels From Living on the Coast, WI Sea Grant, 2003
Editor's Notes
- Description from Operating Guidance: Raster grid of the total water level depths calculated as the difference (in feet) between the wave crest elevations, obtained from the WHAFIS model, and the ground. The depth grid is created using a combination of wave setup, stillwater, and wave height elevations. The wave crest elevation will not be created in areas controlled by wave runup. This grid should only be produced for recurrence intervals for which the wave crest elevations have been calculated/estimated, so as to represent the total depth of flooding, and not just the portion attributed to stillwater. Therefore, coastal flood depth rasters are typically generated for only the 1% annual chance flood unless wave heights have been computed for the other flood frequencies. Text from FRM graphic: Flood depths illustrate the Town of Islands’ severity of flood risk from coastal flooding, including wave action. The depths reflect the difference between the wave crest elevation and the ground for the 1-percent-annual-chance (base) flood. Dark blue colors show deeper flood conditions; lighter blue colors show shallower flood conditions.
- Description from Operating Guidance: Census block polygons of risk assessment and loss estimate results for each frequency-based flood that was modeled (e.g. 10%, 1%, etc. annual chance). The source of the input depth grids used for the analysis should be the total water level depth grids. If wave height information has been calculated/estimated for all return periods, the annualized loss will also be computed and stored for each census block. Text from FRM graphic: In the Town of Islands, flood losses have been calculated using Hazus, FEMA’s standard methodology for risk assessment. Annualized flood losses in this town are displayed by census block data. Hazus analysis and data can support adoption of higher regulatory standards for structures in high loss areas. It can also provide justification to fund mitigation actions to protect citizens and properties from losses during future coastal flood events.
- Description from Operating Guidance: Polygons that reflect hypothetical increases of 1, 2, and 3 feet in the total water levels. Calculated as the inland extent of the coastal depth grid plus the increased inundation. Individual polygons can be produced based on any combination of the depth grid (e.g. 10%, 1%, etc.) and increase (1, 2, or 3 ft). Additional increases besides 1, 2, or 3 feet are allowed if specifically requested. Text from FRM graphic: If flood hazard levels exceed the base flood (purple), additional areas would be at risk. Areas that would be inundated by an additional 1, 2, or 3 feet of flooding above the base flood are shown in yellow, orange, and red, respectively. In the Town of Pines, an additional 2 square miles of developed areas would be at risk of flooding if flood levels exceed the base flood by 3 feet. Possible causes for higher flood levels include more severe storm events and climate change impacts such as sea level rise.
- Tiered Engagement Approach - GLCFS project in a way that ultimately demonstrates the Risk MAP program’s success in acting as a catalyst for communities to take action to reduce their risks from natural hazards. Community engagement plan – outline the planned engagement with each community, or groups of communities, throughout the project (i.e. group or individual meetings, contact frequency, deliverables, etc). begin to document some potential mitigation action ideas that would be of interest to the communities. The Great Lakes Mitigation Action Strategy “Great Lakes Mitigation Action Ideas” excel will be utilized to help create a list specific to each community. identify a list of questions and discussion points to use during community interviews highlight potential synergies that can likely be leveraged during the action engagement project to help facilitate implementation of actions. Example synergies are also available in the Great Lakes Mitigation Action Strategy, as well as a template for the Community Engagement Plan. begin to develop an outline for the Coastal Community Action Advancement Plan An outline of the Community Engagement Plan can be found in the Great Lakes Mitigation Action Strategy. Each Tier 1 community receives one plan, and each Tier 2 group receives one plan. The content and forma The draft Community Profile, Map, and Community Engagement Plan will be provided to the Core Team for a two-week review, comments, and feedback. Core Team insights will be incorporated and the draft Community Profile and Map will be digitally provided to stakeholders attending the upcoming interview. Great Lakes Mitigation Action Strategy excel databases will be referenced as they contain additional information on potential actions already identified for Great Lakes Tier 1 and Tier 2 communities. The profile and map can include but not be limited to available spatial and tabular data such as: Key influencers, community priorities, and standard profile information. Known risks and mitigation opportunities (e.g., critical facilities, schools, buildings at risk in historic districts). Flood risk information, including losses, Known key influencers, community priorities, recent mitigation efforts, mitigation priorities; Status of HMP and background on effective plan’s preparation (e.g. locally-prepared, consultant-prepared, county-prepared, etc.); Known hot spot areas of risk (map), including available spatial data on repetitive loss, critical facilities, areas of concern identified through review of effective FIRM data and HMP; Potential “likely” actions identified through Mitigation Specialist review of HMP, including community capabilities, needs, and interests; Other relevant data based on state insights, including information from most recent CAV; Flood study-related information, pulled from CNMS and ongoing/recent project review; Other collected data Community Action Advancement Summary Plan will consist of a brief (2-3 pages) written summary with supplemental maps and tables that provide the following information : Community information including summary of community’s mitigation history, background, lessons learned, and any ongoing mitigation/resilience efforts; High priority Hot Spots, each supplemented with information about the risk/issue, identified potential actions at three levels where appropriate (no cost, minimal/moderate cost, moderate/high cost), “likely” action (as identified by community), obstacles/challenges to initiation/implementation, steps to advancement, relevant State/Federal resources and contacts, and other recommendations to support progress; Final Community Profile, Community Mitigation Hot Spots Map, Contact information, and list of State/Federal resources. Internal appendix (for distribution only to Core Team) of Risk MAP support recommendations, which will provide additional information on the “likely” actions such as local leaders/stakeholders, resources, and capabilities to influence progress and recommendations for possible State/Federal/contractor action advancement support.
- Scope – 6 Tier 1 and 16 Tier 2 communities (2 groups) Future funding for more action engagement and for support with advancing mitigation action Chicago: Local stakeholders and champions – Chicago Park District Unique shoreline characteristics - Land use near shoreline – building codes limit construction lakeward side of Lake Shore Drive Infrastructure – road is the lakeside limit for construction, millions of dollars spent to protect the buildings past the road (a couple exceptions on the lakeward side) – seawalls constructed all protected
- Hotspot