Tsukudome Second Hook

A Brick Tunnel Through a River Embankment

Tsukidome Niban-hi (築留二番樋, also written Tsukidome Nibanhi), the No. 2 Sluice at Tsukidome in Kamiichi, Kashiwara City, Osaka Prefecture, is a Meiji era brick intake culvert added to the national register of Tangible Cultural Properties on 12 October 2001. It is 55 metres long and 2 metres wide, and it still draws water from the Yamato River into the Nagase River every day.

A hi is a sluice: a tunnel driven through an embankment so that water can be taken from a river into a canal on the far side. This one sits where the Nagase branches from the Yamato, and it belongs to the aftermath of one of the largest civil engineering projects of Edo period Japan.

The old Yamato River ran north-west from Kashiwara across the Kawachi plain and flooded so persistently that villages petitioned the shogunate for decades. In 1704 the river was cut through to the west on a new course to Osaka Bay. The work took eight months. Naka Jinbei, headman of Imagome village and the campaign's most persistent advocate, has a bronze statue on the embankment above the sluice.

The diversion solved the flooding and created a problem. Villages downstream of the old channel had irrigated their fields from a river that no longer passed them. The answer was to build intakes through the new embankment and feed the abandoned riverbed as a canal. Three were built at Tsukidome, numbered one, two and three from the east. The No. 1 sluice went in with the embankment itself in 1704; No. 2 and No. 3 followed in 1705, the second cut into a bank that had only just been completed.

Why a Working Sluice Carries National Registration

The structure standing today is not the sluice of 1705. That one was timber, set into earth and stone revetment, and it was patched repeatedly for a century and a half. A flood in 1887 destroyed it. The rebuilding of the following year used brick, then the newest structural material to reach Japan from Europe, chosen because the community wanted something that would not fail again.

What the builders produced is unusual enough to be worth describing in detail. The barrel is not a plain semicircular tube. Its section is a horseshoe: the arch springs from walls that curve rather than rising vertically, the profile a railway tunnel uses. Among Japanese irrigation culverts that shape is rare. The Agency for Cultural Affairs records the mouth as a semicircular arch about 1.6 metres in diameter turned in three rings of brick; Kashiwara City measures the widest point of the arch at 157 centimetres.

The brickwork is laid mostly in English bond, courses of headers alternating with courses of stretchers, which is the stronger of the two patterns in common use and was applied to the downstream portal in particular. Only the lower half of the face wall departs from it, running in stretchers alone. Granite caps the tops of the walls, granite forms the coping over the portal and the wing walls that splay out from it at an angle, and granite paves the floor of the barrel.

Registration came in 2001 under the criterion for structures contributing to the historical landscape of the country, with the number 27-0142. Osaka Prefecture notes that among registered irrigation structures this is the oldest brick example in Japan, and that a brick structure extending 55 metres is uncommon on its own terms.

One point deserves flagging for anyone checking sources. The Agency for Cultural Affairs lists the date as the late Meiji era, within a bracket of 1868 to 1911. Kashiwara City and Osaka Prefecture both give 1888, and a stone monument in the adjoining park records completion in that year. The discrepancy sits in the public record unresolved.

Recognition went further in 2018. On 13 August that year the International Commission on Irrigation and Drainage, meeting for its 69th International Executive Council, inscribed the Yamato River Diversion Tsukidome System on the register of World Heritage Irrigation Structures. The system means the Nagase and Tamakushi canals fed from the Tsukidome sluices. Seventy-five villages once organised themselves as the Tsukidome sluice guild to maintain it, watering some 4,000 hectares; the guild's successor, the Tsukidome Land Improvement District, owns the sluice today and still supplies roughly 226 hectares across Kashiwara, Yao and Higashi-Osaka.

Standing on the Embankment

The sluice is easy to reach and easy to walk past. Andō Station on the Kintetsu Osaka Line is about 150 metres east, two or three minutes on foot, and Yamatogawa Chisui Memorial Park runs along the embankment directly above. The park is open at all hours and free.

From the riverside face you can watch water enter the mouth of the culvert; from the town side you see it emerge into the head of the Nagase. Standing at either end for a few minutes makes the arrangement legible in a way that no diagram does. The brick has weathered to a colour that separates it plainly from the concrete around it.

The interior is closed. This is live infrastructure carrying irrigation water, and the barrel has in any case been reinforced with grout injection and concrete, so its original construction is no longer fully visible. Photography from the park and the public road is unrestricted.

Two short walks extend the visit. The No. 3 sluice stands a little over 200 metres west, and the flows from the two meet about 500 metres north at a point called Ochiai, where the channel widens into the Jukken Iji, the ten-ken canal, roughly 18 metres across. Downstream of that, the path along the Nagase has been laid out as a walking route to JR Kashiwara Station. The park itself holds the Naka Jinbei statue and a group of monuments marking the 250th and 300th anniversaries of the diversion.

Come in early summer if you can choose. The canals run full for the rice-planting season, and a sluice with water moving through it explains itself better than a dry one.