A River Rebuilt as a Garden
On the night of September 17, 1945, two days after Japan's surrender, the Makurazaki Typhoon swept across Hiroshima Prefecture. On the sacred island of Itsukushima, better known today as Miyajima, the rain loosened the slopes of Mt. Misen and sent a wall of mud and rock down the Momijidani valley behind Itsukushima Shrine. Records from the time describe a landslide breaking loose near the seventh station of the 529.8-meter peak. When the water finally settled, parts of the shrine complex had been carried away and the area beneath its floors lay buried under roughly 18,000 cubic meters of earth and stone.
What rose from that disaster is unusual enough that engineers had to coin a word for it. The Momijidani River Garden Erosion-Control Works, completed in 1950, is a functioning flood-defense system built to look like a Japanese garden. The Japanese term invented for the project, teien sabō or "garden erosion control," describes exactly what it is: a chain of check dams, bed-consolidation works, and stone-lined channels that protect the shrine below while reading, to the visitor walking past, as a composed landscape of boulders, pools, and small waterfalls.
How a flood-defense project became a garden
The recovery was not handled as ordinary civil engineering. Because Itsukushima carried the dual status of Historic Site and Place of Scenic Beauty, the people of Miyajima pressed for repairs worthy of that designation, and prefectural disaster officials and the Ministry of Education agreed. In 1948 a committee was formed for the "Itsukushima Historic Site and Scenic Beauty Disaster Recovery Works," drawing together ministry, prefectural, and town officials, shrine representatives, members of the national and prefectural assemblies, and academic specialists.
The committee produced a guiding document, the Statement of Intent for the Rock Garden Construction, that set rules unlike anything in a standard engineering manual. Boulders and stones, large and small, were never to be damaged or split; they were to be used as found, with their rough natural faces exposed. Trees were to be left standing wherever possible. Concrete, where it was needed for strength, was to be wrapped in undressed stone so that no bare gray surface met the eye. The construction itself fell to Japanese garden craftsmen from the Hiroshima area, who set each stone by hand while prefectural engineers checked the structural work and landscape scholars advised on composition.
Moving stone under those rules was slow work. Crews used a manual hauling rig known locally as the kagura-san to shift the largest boulders into place without chipping or cracking them. Work ran for three years. The Momijidani channel was finished across the first two seasons, the neighboring Shiraito River in the final year, and the project was declared complete in 1950.
Why it was designated
For decades the works were admired mainly by sabo engineers and landscape specialists, including visitors from overseas, who recognized how rare it was to find a debris barrier that disappeared so completely into its setting. On December 23, 2020, the Agency for Cultural Affairs designated the facility an Important Cultural Property under the criterion of high historical value.
The designation broke new ground in two ways. It was the first postwar civil-engineering structure in Japan to receive the status, listed alongside the Saikai Bridge in Nagasaki Prefecture. And it was honored not only for its design but for the circumstances of its making: in the disorder of the immediate postwar years, national and local government worked with the General Headquarters of the Supreme Commander for the Allied Powers to repair a cultural property, a rare instance of that kind of cooperation. The designation covers a stretch of about 688 meters of stonework, and an attached group of 86 related project documents was listed with it.
What to look for on the walk
The designated section runs along the river inside Momijidani Park, the city park planted with more than two hundred maples that gives the valley its name. A walk of roughly twenty minutes from the vermilion Momijibashi bridge takes you past the full sequence. Five numbered check dams step up the valley, each faced in fieldstone so that the concrete core stays hidden; the lowest are barely recognizable as dams at all. Between them, low stone sills break the gradient into a series of small drops, a design choice meant to keep the fast water from scouring the bed during a flood.
Look closely at the stonework and the garden logic shows through. Pools and miniature cascades were placed deliberately rather than left to chance, and at the second dam one upright stone is set in the manner of a "carp stone," a motif borrowed straight from Japanese garden practice. The uppermost reach opens into the Rock Garden, where the boulders the typhoon tore loose were arranged into the composition the project was named for.
Because the whole valley sits within the registered area of the Itsukushima Shrine World Heritage site, the maples here draw crowds in late autumn, when the foliage turns and the water runs clear over the stones. The path is also the route many visitors take on their way to the Miyajima Ropeway station, so the works are easy to fold into a day on the island.
Around the valley
Momijidani Park sits a short walk inland from Itsukushima Shrine, the floating-torii shrine that is the island's main draw. Just downstream of the garden works stands Iwasō, a ryokan founded in the late Edo period whose detached rooms overlook the river. From the top of the valley the Miyajima Ropeway climbs toward the summit walks of Mt. Misen, and the temple of Daishō-in lies on the slope to the south. The island is reached by a ten-minute ferry from Miyajimaguchi, itself a short train ride from central Hiroshima.
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- Find tours, activities & transport passes near Momijidanigawa Garden Erosion Control Facility
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Q&A
- Can I actually visit the erosion-control works?
- Yes. The designated section lies inside Momijidani Park, a public city park that is open and free to enter. You can walk the riverside path alongside the dams and channels at any time.
- When is the best time to go?
- Late November is the celebrated season, when the park's two hundred-plus maples turn red. Spring and early summer are quieter and the stonework and running water are easier to study without the crowds.
- How do I get there from Itsukushima Shrine?
- It is a walk of about ten to fifteen minutes inland from the shrine. Follow signs for Momijidani Park or the Miyajima Ropeway; the works line the river along that route.
- Why is a concrete dam called a cultural property?
- The works were the first postwar civil-engineering structure in Japan to be designated an Important Cultural Property, recognized for the way garden design was fused with flood defense and for the postwar cooperation that built it.
- Is it part of the World Heritage site?
- The valley falls within the registered area of the Itsukushima Shrine World Heritage site, though the World Heritage listing and the Important Cultural Property designation are separate things.
Basic Information
| Name | Momijidanigawa Teien Sabō Shisetsu (Momijidani River Garden Erosion-Control Works) |
|---|---|
| Location | Miyajima-cho, Hatsukaichi City, Hiroshima Prefecture |
| Designation | Important Cultural Property (designated December 23, 2020) |
| Criterion | Works of high historical value |
| Period | Shōwa era; completed circa 1950 |
| Structure | Stone and concrete construction; total length approximately 688.2 meters |
| Count | 1 site (with 86 related documents listed as attached property) |
| Owner | Hiroshima Prefecture / Hatsukaichi City |
| Access | Inside Momijidani Park, about a 10 to 15 minute walk from Itsukushima Shrine; open and free |
References
- National Database of Designated Cultural Properties, Agency for Cultural Affairs
- https://kunishitei.bunka.go.jp/bsys/maindetails/102/00005288
- Cultural Heritage Online (National Institutes for Cultural Heritage)
- https://bunka.nii.ac.jp/heritages/detail/579736
- Important Cultural Property: Momijidanigawa Garden Sabo Facility (Hiroshima Prefecture Sabo Division)
- https://www.sabo.pref.hiroshima.lg.jp/portal/sonota/momijidani/exmtl.html
- Momijidani Park and the Garden Erosion-Control Works (Hatsukaichi City)
- https://www.city.hatsukaichi.hiroshima.jp/soshiki/26/52152.html
- Hiroshima University Digital Museum
- https://www.digital-museum.hiroshima-u.ac.jp/~main/index.php/紅葉谷川庭園砂防施設
Last verified: 2026.06.03