Shock as Ibaraki’s Gold Coast Faces Disappearance—60% of Its Beaches Could Be Gone by 2100, Sending Property Values Plunging

Beaches across Japan are disappearing one after another

This summer, Hokota City in Ibaraki Prefecture decided not to open Otake Coast Hokota Beach, which has long been popular with beachgoers for its expansive stretch of sand and scenery, earning it the nickname “Ibaraki’s Gold Coast.” The decision was made because waves have eroded the beach, exposing concrete blocks that had previously been covered by sand, making it no longer safe to enjoy swimming there.

“Ibaraki’s Gold Coast” is not the only beach facing a crisis.

The coastline of Joetsu City, Niigata Prefecture, is reportedly retreating by about 2 meters a year, while beaches in the Shonan area along Sagami Bay are also being eroded at a faster rate than expected.

A survey by the Ministry of Land, Infrastructure, Transport and Tourism estimates that the amount of sediment supplied by major rivers has declined by about 50% over the past 100 years. According to research by the Japan Travel and Tourism Association, the number of beaches open for swimming in Japan fell from 1,379 in 1993 to 969 in 2024. In addition to beach erosion, the aging of beach managers and other factors have contributed to beach closures across the country.

The real cause of disappearing beaches

“Beach erosion has been featured in the news more and more frequently, but this isn’t something that has only started happening in the past few years. Experts have been sounding the alarm for 30 or 40 years already.”

So says Hiroshige Yokoki, a professor at Ibaraki University who specializes in coastal environmental engineering. Yokoki began working in coastal environmental engineering about 30 years ago, after joining Ibaraki University and hearing people say, “The beaches used to be much wider.” (The following quotations are from Professor Yokoki.)

So why are Japan’s beautiful sandy beaches gradually disappearing?

“Beaches are formed when sediment carried downstream by rivers accumulates at river mouths. But once dams are built or sediment is removed from rivers through dredging, less sediment reaches the river mouths. Meanwhile, waves gradually erode beach sand a little bit every day. As a result, more sand is being washed away than is being carried in, and the beaches have gradually been eroded.”

Even a massive 1-kilometer-long breakwater powerless

Experts have not simply stood by and watched as the beaches disappear.

“About 30 years ago, we thought, ‘Let’s try to keep as much of the sand carried away by the waves as possible,’ so we built breakwaters to protect the beaches.”

The rate of erosion slowed, but the effect did not last. The sand that accumulated alongside the breakwaters eventually rose above them and was carried away. So the thinking was: why not build an even longer breakwater? Ibaraki Prefecture constructed massive breakwaters known as headlands. Some extend for as much as 1 kilometer, but even these are ultimately only a matter of time before the sand begins to overtop them.

“Headlands were not a fundamental solution either.”

Could property values plummet? The crisis triggered by disappearing beaches

The loss of beaches does not simply mean the disappearance of places for leisure.

“Because beaches have a gentle slope, waves gradually break as they approach the shore, helping protect homes and roads from high waves. That is why they are called ‘natural breakwaters.’ They also play an important role as habitats for wildlife.”

According to a 2022 survey by the Ministry of the Environment, about 40% of beaches known as sea turtle nesting grounds have narrowed over the past 50 years.

At this rate, it is said that as much as 60% of Japan’s beaches could disappear by 2100.

Chigasaki City in Kanagawa Prefecture has been putting considerable effort into a project known as “yoihin,” or beach nourishment. This involves transporting sediment from other locations and depositing it on beaches. In Chigasaki, beach erosion became particularly severe around 1975, with some areas seeing the shoreline retreat by as much as 50 meters over the course of 50 years. Not only did this damage the scenery, but high waves also began hitting the national highway running along the coast. There are concerns that resort condominiums along the waterfront could suffer a sharp decline in property values, as well as the possibility that protective structures could be lost during a disaster.

What will the new era of beach protection look like?

The materials used for beach nourishment are sediment accumulated at Sagami Dam and marine sand that has accumulated west of Chigasaki Fishing Port. Rather than depositing the sediment from the dam directly onto the beach, it is placed along the middle reaches of the Sagami River and allowed to flow naturally toward the sea with the river current.

The amount of sediment transported from the dam is 30,000 cubic meters a year. Since this has been carried out every year since 2006, it represents an enormous amount of effort.

It seems that a considerable amount of taxpayer money is being invested in the project, but in modern society, dams and riverbank protection works are indispensable. So how should we tackle this problem?

“There is currently research into technology that creates bypasses around dams to allow sediment to flow downstream. But for now, there are two things we can do: sand bypassing, in which sediment accumulated at dams and elsewhere is returned to the beach, and sand recycling, in which sand that has been moved and deposited by waves is returned to the beach.

“We don’t necessarily have to do this every year; we could do it every three or five years. I believe we need to control the movement of sand. It costs money, but it can be done more cheaply than constructing structures.”

▼ Hiromune Yokoki — Dean of the College of Engineering and Dean of the Graduate School of Science and Engineering at Ibaraki University. Professor in the Urban Systems Engineering field of the Institute of Applied Sciences. His specialties include climate-change adaptation measures and earth and coastal environmental engineering. He particularly researches impact assessments and adaptation measures related to climate change. Today, rather than limiting himself to fields such as coastal engineering and environmental engineering, he aims to work on projects that benefit society.