Building Resiliency in Great Lakes Communities

June 03, 2015

Jaspreet Randhawa, CFMLaura Kelliher, CFM

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

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)

Introduction to the Great Lakes Coastal Flood Study

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

Data: Risk MAP Flood Risk Datasets

• Changes Since Last FIRM (CSLF)• Coastal Depth Grids• Flood Risk Assessment

(HAZUS)• Coastal Inundation

7

Data: Changes Since Last FIRM

SFHA Decrease

Unchanged

Unchanged

SFHA Increase

Unchanged

SFHA Increase

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

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

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

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

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

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

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

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

Example hotspot map

Example Profile

Common Coastal Features ofGreat Lakes

Common Coastal Features ofGreat Lakes

Common Coastal Features ofGreat Lakes

Impacts at Varying Lake Levels

From Living on the Coast, WI Sea Grant, 2003