EnvironmentCities retreat from water as coastal flooding worsens

Cities retreat from water as coastal flooding worsens


Miami & Delaware, United States: When the tide gets exceptionally high in Charleston, South Carolina, coastal streets start to run with seawater. Some yards become ponds, and residents pull-on rain boots.

The city also gets a lot of rain. After homes in one low-lying neighborhood flooded three times in four years, the city offered to buy out 32 flood-prone townhomes and turn the land back into open space that can be used for managing future floodwater.

It’s a strategy coastal cities from Virginia to California are contemplating more often as tidal flooding increases with sea-level rise.

Cities all along the U.S. coasts have seen high tide flooding days increase. In 2021, the U.S. coasts are projected to see an average of three to seven high-tide flooding days, rising to 25-75 days by midcentury, the National Oceanic and Atmospheric Administration warned in its annual high-tide flooding outlook, released July 14, 2021.

Low-lying Charleston saw a record-breaking 14 days of high-tide flooding in 2020, and that number is forecast to rise over the next three decades. Parts of the city count even more flooding.

Charleston is considering new sea walls to protect against hurricanes, and other measures to try to keep tidal and storm flooding out of threatened neighborhoods. But it has also started helping residents relocate away from high-risk areas. It’s a strategy known as a managed retreat – the purposeful movement of people, buildings, and other infrastructure away from highly hazardous places.

U.S. high-tide flooding days projected for 2021

High-tide flooding is now occurring twice as frequently as it did in 2000, and it’s expected to double again in the next 10 years. By 2050, without additional adaptation measures, several areas are projected to face more than 100 days of high tide flooding.

NOAA projections for May 2021-April 2022; released July 14, 2021. Map: The Conversation/CC-BY-ND  Source: NOAA

Managed retreat is controversial, particularly in the United States. But it isn’t just about moving – it’s about adapting to change and building communities that are safer, addressing long-overlooked needs, and incorporating new technologies and thoughtful design for living and working in today’s world.

We argue in a special issue of the journal Science that managed retreat is an opportunity to preserve the essential while redesigning high-risk areas in ways that are better for everyone.

What managed retreat can look like

U.S. Marine Corps Gen. Oliver P. Smith famously said of a retreat he led during the Korean War: “Retreat! Hell! We’re just advancing in a different direction.” Like Gen. Smith’s maneuver, retreat from climate change-related hazards, at its core, is about choosing a new direction.

A managed retreat could involve turning streets into canals in coastal cities. It could mean purchasing and demolishing flood-prone properties to create open spaces for stormwater parks that absorb heavy rains or retention ponds and pumping stations.

5 illustrations of a coastal town showing different ways managed retreat and other tools can be combined to adapt
Managed retreat is one part of an adaptation toolkit. Elena Hartley

In some cases, managed retreat may involve building denser, more affordable housing that’s designed to stay cool, while leaving open spaces for recreation or agriculture that can also reduce heat and absorb stormwater when needed.

Managing retreat well is challenging. It affects numerous people – the residents who relocate, their neighbors who remain, and the communities where they move – and each may be affected differently.

Soldiers Grove, Wisconsin, relocated its flood-prone business district in the late 1970s and used the opportunity to heat the new buildings with solar energy, earning the nickname “Solar Village.”

The move reinvigorated the local economy; yet while the project is hailed as a success, some residents still miss the old town.

For a managed retreat to be a viable strategy, relocation plans must not only help people move to safer ground but also meet their needs.

This may involve a wide range of social issues, including cultural practices, affordable housing, building codes, land use, jobs, transportation, and utilities.

Since high-risk areas are often home to low-income communities and Black, Indigenous, and other communities of color, addressing climate risk in these areas may also require addressing a national legacy of racism, segregation, and disinvestment that has put these communities at risk and left many with few choices to address floods, fires, and other hazards.

At its simplest, a managed retreat can be a lifeline for families who are tired of the emotional and financial stress of rebuilding after floods or fires but cannot afford to sell their home at a loss or don’t want to sell and put another family at risk.

Talking about managed retreat

Even if an individual or community decides not to retreat, thinking critically and talking openly about the managed retreat can help people understand why remaining in place is important, and what risks they are willing to face in order to stay.

The losses involved in moving can be obvious, including cost, but there are losses to staying in place, too: physical risk of future hazards, increased emotional and financial stress, potential loss of community if some residents or businesses leave to find safer ground, pain from watching the environment change and lost opportunities to improve.

If people can articulate why it is important to remain in place, they can make better plans.

Maybe it is important to stay because a building is historic and people want to protect that history.

That opens up creative conversations about the ways people have preserved risk-prone historic buildings and sites.

And it invites others to help document that heritage and educate the community, perhaps through oral histories, video records, or 3D models.

Maybe it is important for owners to stay because the land has been in the family for generations.

That could kick-start conversations with the next generation about their goals for the land, which may include preservation but may also include changes.

Maybe a deep, emotional attachment to a community or home could make a person want to stay.

Conversations could focus on moving nearby – to a new house that’s safer but still part of the community – or physically relocating the house to a safer place.

It could also mean finding strategies, like life estates, that allow people to stay in their home as long as they want but would prevent a new family from moving in and putting their kids at risk.

If staying seems important because the local economy depends on the beach, that could start a conversation about why moving back from the beach can be the best way to save the beach and its ecosystem, to prevent walls from narrowing it and to maintain public access without homes on stilts hovering over the tide.

Thinking carefully about what parts of our lives and communities should stay the same opens space to think creatively about what parts should or could change

This is an updated version of an article originally published on June 21, 2021.

A.R. Siders has received funding on related projects from The Nature Conservancy. She consults with state and local governments on planning for climate change.

Katharine Mach has received funding relevant to climate resilience through the Miami Foundation. She has consulted for local governments on planning for climate change and served in several advisory roles.

Cover image: Flooding at high tide on Sunday morning, September 20, in Charleston, South Carolina. (Image credit: Eric Dunphy)

This story was written by A.R. Siders, Assistant Professor, Disaster Research Center, University of Delaware, and Katharine Mach, Associate Professor of Environmental Science and Policy, the University of Miami for The Conversation.

The Conversation
The Conversation is a non-profit news organization disseminating academic knowledge to readers like you. Scholars who are specialists on issues pertaining to public interest write articles with the assistance of editors who help unlock the fluidity of the information. The Conversation has newsrooms in the United States, the United Kingdom, Australia, South Africa, and France, and was created in 2011.


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