The Shock of the “Ibaraki Gold Coast” Disappearing… By 2100, 60% of the Sandy Beaches Will Be Gone, and Real Estate Values Will Plummet

Japan’s Beaches Are Disappearing One After Another  

This summer, Hokota City in Ibaraki Prefecture decided not to open the “Otake Coast Hokota Beach,” a spot beloved by beachgoers for its long sandy shore and scenic views—so much so that it was dubbed the “Gold Coast of Ibaraki.”The reason was that wave erosion had stripped away the sand, exposing the concrete blocks used for the seawall that had previously been buried beneath it, making it unsafe for swimmers to enjoy the beach.

It is not just “Ibaraki’s Gold Coast” that is in crisis.

The coastline in Joetsu City, Niigata Prefecture, is receding at a rate of about 2 meters per year, and erosion is reportedly progressing faster than expected along the beaches of the Shonan area facing Sagami Bay.

A survey by the Ministry of Land, Infrastructure, Transport and Tourism estimates that sediment supply from major rivers has decreased by about 50 percent over the past 100 years, and a study by the Japan Tourism Promotion Association reports that the number of domestic beaches, which stood at 1,379 in 1993, had fallen to 969 by 2024.In addition to beach erosion, factors such as the aging of facility managers have contributed to the closure of beaches across the country.

The “Real Cause” of Sandy Beach Disappearance

“While beach erosion is increasingly being covered in the news, this isn’t something that has just started happening in the last few years. Experts have been sounding the alarm for 30 or 40 years now,”

So says Professor Yuzo Yokoki of Ibaraki University, who researches marine environmental engineering. Professor Yokoki began his work in marine environmental engineering about 30 years ago after taking up a position at Ibaraki University and hearing that “the beaches used to be much wider” (quotes below are from Professor Yokoki).

Why, exactly, are Japan’s beautiful sandy beaches disappearing?

“Sandy beaches are formed when sediment carried by rivers accumulates at river mouths. However, the construction of dams and dredging operations that remove sediment from rivers have reduced the amount of sediment reaching the river mouths. As a result, , at the same time, the sand on the beaches is gradually eroded away by the waves every day. As a result, the amount of sand being eroded exceeded the amount being deposited, causing the beaches to gradually erode.”

Even a massive 1-kilometer-long breakwater proved ineffective  

Faced with the reality of the shrinking sandy beach, experts weren’t simply standing idly by.

 “About 30 years ago, with the idea of ‘preserving as much of the sand carried away by the waves as possible,’ we built a breakwater to protect the sandy beach.”

Although the rate of erosion slowed, it didn’t last long.The sand that accumulated alongside the breakwater eventually spilled over it and was washed away. Thinking that building a longer breakwater might be the solution, Ibaraki Prefecture constructed a massive structure known as a “headland.” Although this structure stretches 1 km in length, it, too, is only a matter of time before the sand eventually overflows it.

“The headland didn’t provide a fundamental solution either.”

A Property Market Crash? The Crisis Brought on by the Disappearance of Sandy Beaches

The loss of sandy beaches doesn’t simply mean the disappearance of recreational spaces.

“Because sandy beaches have a gentle slope, waves break gradually, protecting homes and roads from high waves. That is why they are called ‘natural breakwaters.’ They also play a vital role as habitats for wildlife.”

According to a 2022 survey by the Ministry of the Environment, approximately 40 percent of the sandy beaches known as sea turtle nesting grounds have shrunk over the past 50 years.

It is said that if this trend continues, up to 60 percent of sandy beaches could disappear by 2100.

Chigasaki City in Kanagawa Prefecture is devoting extraordinary effort to a project called “beach nourishment.” This involves transporting sediment from other locations and depositing it on the sandy beaches. In Chigasaki, beach erosion has intensified since around 1975, and in some areas, the shoreline has receded by as much as 50 meters over the past 50 years.This was due not only to the deterioration of the landscape but also to high waves that occasionally struck the national highway running along the coast. There are also concerns about the risk of a sharp drop in the property values of seaside resort condominiums and the possibility that breakwaters could be lost in the event of a disaster.

What Are the “New Era” Measures to Protect the Beaches?

The materials used for beach nourishment are sediment deposited at the Sagami Dam and seawater sediment accumulating on the west side of Chigasaki Fishing Port. Rather than depositing the dam sediment directly onto the beach, a natural method is employed: the sediment is placed in the middle reaches of the Sagami River and allowed to flow out to sea with the river’s current.The annual volume of sediment transported from the dam is 30,000 cubic meters. Given that this has been done every year since 2006, it represents a tremendous effort.

Although it is likely that a considerable amount of taxpayer money is being spent on this, dams and riverbank reinforcement projects are indispensable in modern society. How should we address this issue?

 “ Recently, research has been conducted on technologies to create bypasses in dams to allow sediment to flow through, but what we can do right now are two approaches: a ‘sand bypass,’ which releases sediment that has accumulated in dams and other structures, and ‘sand recycling,’ which returns sand that has been moved by waves and deposited elsewhere back to the beach.

These should be carried out not necessarily every year, but every three or five years. I believe it is necessary to control the flow of sand. It does involve costs, but it is less expensive than building new structures.”

▼Hiromune Yokoki: Dean of the Faculty of Engineering and Director of the Graduate School of Science and Engineering at Ibaraki University. Professor in the Urban Systems Engineering Division, Applied Science and Engineering Field, at the Academic Research Institute.His areas of expertise include climate change countermeasures and Earth and coastal environmental engineering. In particular, he conducts research on impact assessments and adaptation strategies related to climate change. Currently, he is focused on contributing to society in ways that transcend the boundaries of his specialized fields, such as coastal engineering and environmental engineering.