An Erosion-Control Dam at the Head of the Karasu River
The Karasugawa Upper Sabo Dam (烏川上流砂防堰堤) is a concrete gravity erosion-control (sabo) dam built in 1951 at the head of the Karasu River in Kawaura, Kurabuchi-machi, Takasaki City, Gunma Prefecture, and was registered as a Registered Tangible Cultural Property (structure) on August 3, 2006. It stands in a gorge on the uppermost reach of the river, which rises on Mount Hanamagari (Agency for Cultural Affairs).
The Agency for Cultural Affairs records it as a concrete gravity dam 67 metres long and 18 metres high; registration number 10-0171. It is managed by the Tone River Sabo Office of the Ministry of Land, Infrastructure, Transport and Tourism.
Erosion Control on the Karasu River
According to the Tone River Sabo Office, the upper Karasu River suffered major disasters in 1910 and 1935, after which erosion control began. This dam was built in 1951 on the uppermost main stream to stop debris piled upstream from washing down.
It was funded with US counterpart aid funds and built in about a year using many advanced techniques. More than half a century on, it remains central to flood protection in the Karasu basin (Tone River Sabo Office).
Why It Was Registered
The Karasugawa Upper Sabo Dam was registered as a structure that contributes to the historic landscape of the country. The Agency for Cultural Affairs notes that this large overflow dam creates a grand water scene amid the restored greenery of the gorge.
The Tone River Sabo Office notes that there are only five large mortared-masonry dams over 15 metres high managed by the ministry in Gunma.
What to Look For
The Karasugawa Upper Sabo Dam is built on bedrock, its face laid in diagonal tanizumi masonry of dressed stone (Agency for Cultural Affairs). The sabo office describes a rubble-concrete core faced with herringbone-pattern mortared masonry and a stone-paved crest.
Water pours over the crest of this overflow dam, falling down the masonry face to shape the gorge landscape (Agency for Cultural Affairs).
Visiting the Karasugawa Upper Sabo Dam
According to the Tone River Sabo Office, a small park looking onto the dam has been laid out. The location is Kawaura, Kurabuchi-machi, Takasaki City. Take great care near the dam and river, which can rise quickly.
Q&A
- When was the Karasugawa Upper Sabo Dam built?
- In 1951 (Agency for Cultural Affairs).
- How big is the Karasugawa Upper Sabo Dam?
- 67 metres long and 18 metres high, a concrete gravity dam (Agency for Cultural Affairs).
- Why was the Karasugawa Upper Sabo Dam built?
- To stop debris washing down after disasters in 1910 and 1935 (Tone River Sabo Office).
- What is the face of the Karasugawa Upper Sabo Dam like?
- Diagonal mortared masonry of dressed stone with a stone-paved crest (Agency for Cultural Affairs, Tone River Sabo Office).
- When was the Karasugawa Upper Sabo Dam registered?
- On August 3, 2006.
Basic Information
| Name | Karasugawa Upper Sabo Dam (烏川上流砂防堰堤) |
|---|---|
| Location | Kawaura, Kurabuchi-machi, Takasaki City, Gunma Prefecture |
| Designation | Registered Tangible Cultural Property (Structure) |
| Year Designated | Registered 2006/8/3 (Heisei 18) |
| Quantity | 1 structure |
| Dimensions | Concrete gravity dam, 67 metres long, 18 metres high |
| Owner | National government (Ministry of Land, Infrastructure, Transport and Tourism) |
| Public Access | Viewing park nearby |
References
- Karasugawa Upper Sabo Dam (Database of National Cultural Properties, Agency for Cultural Affairs)
- https://kunishitei.bunka.go.jp/heritage/detail/101/00005565
- Registered cultural properties (Tone River Sabo Office)
- https://www.ktr.mlit.go.jp/tonesui/tonesui00003.html
Last verified: 2026.10.08