WICCI’s Coastal Resilience Working Group uses innovative methods and technologies to describe and predict the effects that the changing climate will have on the communities and property owners of Wisconsin’s coastlines.
It is challenging to fully appreciate the potential consequences of changing lake levels, precipitation patterns, and storm events that may result from a changing climate. In part, this is because regional climate and lake level projections are provided via technical data that do not indicate specific consequences for city planners and resource managers. In some cases, the consequences of climate change on coastal communities may not be obvious because projected changes may have conflicting impacts.
Coastal communities need interpretive tools that synthesize distributed data and translate the predictions of regional climate change models and lake level forecasts into user-friendly, local terms that anyone can understand. Such tools will help decision-makers see the connections between climate modeling and the day-to-day decisions they must make.
Summary of Issues and Impacts
Wisconsin’s Great Lakes coast is composed of bluffs, dunes, beaches and waterfront infrastructure. These interconnected coastal features serve as the interface between high-value upland areas and the economic, recreational and cultural assets of the Great Lakes. Processes like fluctuating lake water levels, waves, erosion, sediment transport and slope failure can combine to damage coastal properties and impair the function of waterfront facilities. Climate change threatens to exacerbate the coastal hazards facing Wisconsin’s coastal communities.
Climate Issues Affecting Coastal Resilience
Fluctuating Lake Levels
Both high and low water level extremes are anticipated to continue under a changing climate. This could include potentially higher highs and lower lows than seen in the historical record. This is because both precipitation and evaporation are anticipated to increase under a changing climate, leading to a tug-of-war in water supply into and out of the lakes that may have more extremes than in the past.
Declining Ice Cover
The observed trend of declines in the extent and duration of ice cover on the Great Lakes are expected to continue in a future warmer climate. Reduced ice cover exposes the coast to greater wave energy.
Increasing Wave Energy
Wave energy reaching Great Lakes coasts is expected to increase in the future in part due to anticipated decreases in ice cover extent and duration. A reduction of ice cover will expose the coast to waves for a greater portion of the winter, the season when coastal storm intensity is greatest and large wave events are most frequent. Great Lakes wave energy has also been observed to increase during the summer months, associated with an increased frequency of extreme wind speed events.
Trends of increasing precipitation totals and heavy rainfall event frequency are expected to continue under a changing climate. Increased precipitation is likely to decrease bluff slope stability and increase the likelihood of bluff slope collapse.
Impacts to Coastal Communities
Increased Coastal Flooding, Coastal Erosion, and Infrastructure Damage
Increased wave energy combined with periodic high Great Lakes water levels is likely to increase coastal flooding, coastal erosion, bluff failure and infrastructure damage. Higher lake levels and waves may also increase flooding of rivers and stormwater infrastructure that drains to the Great Lakes due to higher water levels at outlets into the lake. Low water levels will also lead to wave downcutting of the lakebed, wave scour at the toe of shore protection structures and accelerated deterioration of normally submerged timber infrastructure as it becomes exposed to air. Extremely low water level may also lead to insufficient water depths for drinking water intakes to function.
Reduced Bluff Slope Stability
Increased precipitation is likely to lead to a greater number of unstable coastal bluff slopes and subsequent bluff collapses. Greater precipitation and more frequent intense events will increase surface water runoff down the bluff face while additional water infiltrating into the groundwater table will lubricate soil particles and reduces the slope’s stability. This instability will be further compounded by increased erosion from high lake levels and increased wave energy.
Impairment to Nautical Navigation
Periods of extreme low lake levels, potentially lower than seen in the historic record, will result in insufficient water depths for navigation in ports, harbors and marinas. Economic loss can result if vessels are not able to access facilities or need to reduce cargo loads to maintain higher drafts. Safety and accessibility issues may occur if large elevation differences exist between dockage and vessels at both extreme high and low lake levels.
There is no “one-size-fits-all” solution to the impacts of climate change on coastal communities because of the variability of Great Lakes coastal conditions and needs from community to community and even site to site. However, there are a number of general guiding principles that can help coastal communities adapt to the threat of coastal hazards:
Consider Future as Well as Current Conditions
Consider the function of coastal assets under all possible lake levels and don’t make changes based solely on the current lake level.
Address Root Causes
When planning actions, consider the causes of hazard issues before acting with common solutions that may not be appropriate for the situation. Choose management actions that address the actual root cause of coastal hazard issues.
Relocate When Possible
Locate homes, infrastructure and other assets as far from eroding shorelines and floodways as is feasible. It is often easier and cheaper to avoid the impacts of coastal hazards than it is to fight the forces of the Great Lakes.
Plan before coastal hazards have urgent impacts. A proactive coastal vulnerability assessment may help identify priority needs.
Consider Nature-Based Solutions
When possible, work with nature to protect coastal investments. Nature-based or living shorelines may be a suitable option depending on site conditions.
Consider Adjacent Properties
Be aware of the impacts that modifications to the coast may have on coastal processes like sediment transport and wave dynamics. Some coastal modifications may increase erosion at adjacent properties.
Engage the community
Plan together with neighbors and communities when possible to coordinate actions and balance the risks of different stakeholder groups.
Adjust Management Strategies
Make structured and iterative management decisions while constantly monitoring and assessing current and alternative strategies.
Maintain Coastal Protection Structures
Periodic inspections and maintenance of coastal protection structures is imperative to ensure the function and the ability to adapt to changing conditions.
Environmental and Climate Justice Issues
Access to the Great Lakes for recreation, fishing, and cultural experiences is often influenced by socioeconomic factors. This can be due to proximity to Great Lakes access points, resources needed for access (like watercraft), or water quality concerns at convenient access points. Consider incorporating public access to better allow all people to enjoy the Great Lakes as part of resilient approaches to coastal management.
A number of low-lying coastal areas vulnerable to flooding in Wisconsin are home to socially vulnerable populations. Environmental justice should be considered when addressing coastal flooding and local residents and community groups should be engaged to move towards equitable solutions to flooding.
Ozaukee County bluff management
Record-high Lake Superior water levels causing erosion on Wisconsin Point in Superior, Wisconsin
Village of Fox Point beach road protection
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Understanding Great Lakes Coastal Hazard Issues
Booklet describing natural coastal processes and overall strategies to manage risk to coastal properties.
Manual that provides step-by-step instructions on how to estimate risk to Great Lakes coastal property from extreme lake levels, storms and erosion.
Interactive virtual learning activities about coastal resilience issues affecting the Lake Michigan coast of southeastern Wisconsin.
Presentation by Adam Bechle, Wisconsin Sea Grant for Wednesday Nite @ the Lab, June 30, 2021. Presentation discuss the water levels the Great Lakes, their impacts, and the actions communities are taking to adapt to a changing coast.
Publication with an overview of 16 management options for adapting to changing bluffs and beaches.
Adapting to a Changing Coast – Options and Resources for Local Officials in Southeastern Wisconsin Coastal Communities
Publication with 28 policy, permitting, funding, and collaboration options that local governments can pursue to improve their ability to adapt to changing water levels and other coastal hazards.
A guide to help Great Lakes coastal bluff property owners maintain and enhance the stability of their bluffs. Includes a listing of vegetation species suitable for coastal bluffs in Southeastern Wisconsin.
A guide describing different types of nature-based shoreline techniques suitable for the Great Lakes featuring case study examples.
Detailed fact sheet describing different types of shore protection structures and their potential impacts, both positive and negative, on the shoreline.
Detailed fact sheet describing the coastal conditions and processes that can lead to bluff failure and some options for stabilizing the slope of a coastal bluff.
Wisconsin Department of Natural Resources website with information on requirements and considerations for shore protection projects in Wisconsin.
Directory of National Oceanic and Atmospheric Administration (NOAA) guidance, data, tools, trainings, and webinars on natural and nature-based solutions for minimizing coastal flooding, erosion and runoff. A specific resource of interest is the Quick Reference on Nature Base Solutions.
This climate change adaptation community of practice focuses on effective uses of living shoreline ideas and principles in a temperate North American climate. (registration required)
Maps and Data
A technology platform that provides access to maps, data, catalogs, tools, and information to support decision-making about Wisconsin’s Great Lakes coast.
An online portal to discover and access Wisconsin geospatial data, with specially curated Great Lakes coastal data layers.
A web mapping tool to view historic photos of the coast, assessments of bluff and shoreline conditions, and measurements of historic bluff and shoreline recession in a web-based, interactive map of Wisconsin coastal data.
A web mapping tool to examine the potential impacts of lake level changes on shoreline position and water depth in the Great Lakes.
A dashboard interface to access and visualize more than 150 years of Great Lakes water level data, as well as seasonal forecasts and climate change projections of future lake levels.
Webpage with near-term water level forecasts and outlooks, as well as current and historic water level data, water supply data, and more.
Planning and Policy Options
A tool to help communities weigh the effects of common coastal hazards and begin to consider planning and mitigation opportunities that may increase the coastal resilience of their community.
Interactive map provides information about the counties, cities, villages and towns that border Lake Michigan and Lake Superior with links to their government website, interactive map, plans and ordinances.
A report that describes coastal hazards in Wisconsin that includes an erosion hazard model ordinance.
A guide that describes the causes of coastal erosion and provides ordinance language on coastal setbacks, relocatable structures, shoreline protection, stormwater management, site planning, and hazard disclosure.
A website with guidance on Great Lakes coastal hazard resilience featuring case studies, tools, maps, data and publications.
Wisconsin Coastal Resilience Hubs and Networks
CARES works with coastal communities in Kenosha, Racine, Milwaukee and Ozaukee counties to identify vulnerabilities, prioritize resilience opportunities and fund local projects to implement top priorities.
CHAOS aims to help build strong collaborations between western Lake Superior communities impacted by coastal hazards in both Wisconsin and Minnesota.
The Northeastern Wisconsin Coastal Resiliency Study worked with coastal communities in Sheboygan, Manitowoc and Kewaunee Counties to examine their coastal hazard issues and identify opportunities to build resilience strategies into local planning efforts.
WICDI is providing data, tools, and training to Wisconsin’s Lake Superior coastal communities to help tackle a key issue in the region: culvert damage during extreme rain events.
Other Great Lakes-Wide Climate Change Assessments
This Environmental Law and Policy Center report released in 2019. Sections of this report that are particularly relevant to coastal resilience include Section 3.2 Great Lakes ice cover trends, Section 3.4 Changes in lake level, Section 5.7 Coastal Processes, and Chapter 6 Public and economic impacts of changes to the Great Lakes.
The U.S. Global Change Assessment Program’s latest National Climate Assessment was released in 2018. Chapter 21 of Volume II has a synthesis of climate change in the Great Lakes in Box 21.1 on page 893.