The Tall Dam in the Side Valley
Tobigasako Sunadome (鳶ヶ迫砂留, Tobigasako Sunadome) is a late Edo-period stone check dam in a right-bank side valley of the Dōdōgawa in Nishinakajō, Kannabe-chō, Fukuyama City, Hiroshima Prefecture, registered as a Registered Tangible Cultural Property on 3 August 2006.
According to the Agency for Cultural Affairs, it stands on the right-bank tributary that joins the main stream above No. 5. It is 39 metres long and 11 metres high, making it the second tallest of the eight registered Dōdōgawa dams after the 13-metre No. 6. It is one of the two dams that guard side valleys rather than the main channel; the other is Uchihiro, on the right-bank tributary that joins above No. 6. Its registration number is 34-0081, and it belongs to the national government through the Ministry of Land, Infrastructure, Transport and Tourism.
Why It Was Registered
The criterion is contribution to the historic landscape of the country. The Agency describes Tobigasako Sunadome as a large dam built high in a steep ravine that helps stabilise the valley sides. The main-stream dams calm the flow with the sand they trap; a dam deep in a side valley does more to hold the crumbling banks themselves in place.
It is a gravity dam of large granite blocks stepped back at a 7-bu batter, about 0.7 units of setback for each unit of height, and gently arched in plan. That is a slightly flatter profile than the 6-bu batter of Nos. 3 and 5 on the main stream, but the arch is the same idea.
The Agency dates it to the late Edo period, between 1751 and 1829, and records two later rounds of extension, in the Meiji era (between 1868 and 1911) and the Taishō era (between 1912 and 1925). Among the eight registered dams, Tobigasako is the only one described as extended in both periods.
History and What to Look For
The Dōdōgawa Hotaru Dōkōkai, the residents' group that looks after the valley, says an irrigation pond was built here around 1732, but it silted up and burst, and when it was rebuilt it quickly filled with sand again. The group points to the site of a granite quarry on the north side of the valley: exposed granite weathers into loose grit, and grit feeds debris flows.
The group also cites a village gazetteer of 1882 recording twelve sand dams in the Nakajō area by 1738, and suggests that on the Dōdōgawa these included No. 1, No. 6 and Tobigasako. In its view the Tobigasako and Uchihiro valleys shed so much sand that they were dammed early. None of these dates has been confirmed from documents.
Below the stone dam, the group notes six concrete check dams built in 1999. Edo stonework and modern concrete line the same gully, so the valley shows how erosion control has changed. Standing in front of Tobigasako Sunadome, watch how the stepped courses of big blocks curve round to meet each bank.
Visiting
Tobigasako Sunadome is an open-air river structure, free and viewable at any time without booking. Stay off the crest and spillway. No official photography restrictions are published.
It lies up a right-bank side valley, not far from Dōdō Park, but the path into the gully varies with the season and the weather, and the streambed is slippery after rain, so wear proper shoes. The local group has planted this valley with cluster amaryllis, and in late September the way to the dam is lined with flowers. Directions and parking are on the Dodogawa Sunadome group page.
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- Find tours, activities & transport passes near Tobigasako Sunadome (Stone Check Dam)
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Q&A
- Where is Tobigasako Sunadome?
- In Nishinakajō, Kannabe-chō, Fukuyama City, on the right-bank tributary that joins the Dōdōgawa above No. 5.
- How big is Tobigasako Sunadome?
- It is 39 metres long and 11 metres high, second only to No. 6 among the eight registered Dōdōgawa dams.
- When was Tobigasako Sunadome built?
- The Agency for Cultural Affairs dates it to the late Edo period, between 1751 and 1829, with extensions in the Meiji era (between 1868 and 1911) and the Taishō era (between 1912 and 1925).
- Is Tobigasako Sunadome part of the Dodogawa Sunadome?
- Yes. It is one of the eight dams registered together in 2006, alongside Nos. 1 to 6 on the main stream and Uchihiro in another side valley.
- Can I visit Tobigasako Sunadome?
- Yes, free and at any time. It lies up a side valley, so take care underfoot after rain.
Basic Information
| Name | Tobigasako Sunadome (鳶ヶ迫砂留) |
|---|---|
| Location | Totodani, Nishinakajo, Kannabe-cho, Fukuyama City, Hiroshima Prefecture |
| Designation | Registered Tangible Cultural Property (Structure) |
| Year Designated | Registered 2006/8/3 (Heisei 18) |
| Quantity | 1 dam |
| Dimensions | Length 39 metres, height 11 metres |
| Owner | Government of Japan (Ministry of Land, Infrastructure, Transport and Tourism) |
| Public Access | Outdoors; open at all times, free of charge |
References
- Agency for Cultural Affairs, Database of National Cultural Properties: Tobigasako Sunadome
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00005666
- Hiroshima Prefecture Erosion Control Division: Historic Sabo Facilities, Dodogawa Sunadome (Japanese)
- https://www.sabo.pref.hiroshima.lg.jp/portal/map/AreaInfoDetail.aspx?id=187
- Hiroshima Prefecture: Dodogawa No. 6 Sunadome profile sheet (Japanese PDF)
- https://www.pref.hiroshima.lg.jp/uploaded/attachment/177150.pdf
- Dodogawa Hotaru Dokokai: The Sunadome of the Dodogawa (Japanese)
- https://dodogawa.com/sunadome.php
Last verified: 2026.09.24
