sea walls

Natural solutions for coastal defense

May 30, 2024 By EarthWise Leave a Comment

Protecting coastal cities and towns from the dangers of tsunamis, storm surges, and sea-level rise has become an ever-increasing challenge. There are so-called hard coastal defenses as well as nature-based solutions. A new study by the University of Tokyo has found that combining the two types of defenses may be the most effective way to protect, support, and enrich coastal communities.

Sea walls, dikes, dams, and breakwaters are the traditional hard measures. They are popular and have proven track records but are facing challenges to keep pace with increasing climate risks. They are expensive to build and require continuous upgrades and repairs. While they do provide protection from many disaster risks, they also can cause significant disruption to coastal ecosystems as well as to coastal communities.

Nature-based coastal defenses include such things as mangroves and coral reefs. So-called soft measures involve restoring, rehabilitating, reforesting, and nourishing natural ecosystems that protect coastal areas.

The Tokyo researchers analyzed the defense strategies in terms of risk reduction, climate change mitigation, and cost-effectiveness over a 20-year period. The results of the study were that among all coastal defense options in lower-risk areas, hybrid measures provide the highest risk reduction and can harness the advantages of both hard and soft measures.

The findings provide strong evidence for integrating nature-based components into coastal defenses, but these approaches have not yet been adequately tested in circumstances of extreme events and high-risk urgency. Research in this area has important implications for policy makers, coastal planners, and communities looking to make evidence-based decisions.

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A natural touch for coastal defense

Photo, posted October 22, 2021, courtesy of Kevin Dooley via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Coastal Land Reclamation | Earth Wise

April 3, 2023 By EarthWise Leave a Comment

People are artificially expanding the coastlines of cities by extending industrial ports and creating luxury residential waterfronts. Major cities have added 900 square miles to their coastlines just since 2000.

A recent study published in the journal Earth’s Future made use of satellite imagery to analyze land changes in 135 cities with populations of at least 1 million. But population growth is not the only driver of coastal land reclamation. It is popular in places that are eager to enhance their reputation and promote revenue growth.

At present, coastal land reclamation is most common in the Global South, where many economies are growing. In the past, the Global North dominated the use of coastal land construction.

The largest additions to land area occurred in China, Indonesia, and the United Arab Emirates. Port extension is the most common reason for development. Shanghai alone has added 135 square miles of land.

New land is typically created by piling sediments in the ocean, building cement sea walls and structures to contain sediments or cement, or sometimes filling in wetlands and other shallow areas of water near the coast. The ecological impacts of reclamation are immense and, unfortunately, are not always considered. Projects affect both the local ecosystems as well as those of the places where fill materials are obtained.

Industrialization and the need for urban space have driven much coastal reclamation. Some projects, such as the palm-tree-shaped artificial islands of Dubai, are essentially for prestige. Some cities, including Shanghai, are building new land in consideration of future sea level rise.

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New Land Creation on Waterfronts Increasing, Study Finds

Photo, posted October 15, 2010, courtesy of Werner Bayer via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Which Cities To Save From The Changing Climate

October 28, 2019 By EarthWise Leave a Comment

After several years of brutal flooding and hurricanes in the U.S., a distressing debate is emerging: if there is not enough money available to protect every coastal community from the effects of global warming, how do we decide which ones to save first.

Recent research looked at the costs involved in providing basic storm-surge protection in the form of sea walls for all coastal cities with more than 25,000 residents. That number was $42 billion. Expanding the list to include communities smaller than 25,000 people would increase that cost to more than $400 billion. Realistically, that is just not going to happen.

This particular study only looked at sea walls and no other methods for minimizing flood risk, such as moving homes and businesses away from the most flood-prone areas. It also didn’t look at additional and costlier actions that will be required even with sea walls, such as revamping sewers, storm water, and drinking water infrastructure.

The facts are that many cities, especially small ones, will not be able to meet the costs facing them. Those that can’t will depend on federal funding. But even optimistically large proposals for federal infrastructure spending are likely to fall far short of the vast need. Ultimately, the money will end up being spent where it can do the most good – even if it means that some places are left out.

But what criteria will be used to direct the money? Economic value? Historic significance? Population? Political influence?

This is a looming and massive issue whose chief obstacle may be that many officials refuse to acknowledge that it is happening. This is the next wave of climate denial – denying the costs that we are all facing.

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With More Storms and Rising Seas, Which U.S. Cities Should Be Saved First?

Photo, posted October 31, 2018, courtesy of Patrick Kinney via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.