Jizohara Dam

A Key Dam at the Head of the Fan

The Jizohara Dam (地蔵原堰堤, Jizōhara Entei) is a gravity concrete sabo dam completed in 1925 and rebuilt in 1953 at the head of the alluvial fan where the Arakawa River leaves the mountains in Fukushima City, Fukushima Prefecture, and it was registered as a Registered Tangible Cultural Property on March 7, 2008.

The national record gives a crest length of 74 meters and a height of 8.7 meters. Earth embankments extend the stone-faced dam on both sides, and a smaller sub-dam stands downstream; the embankments, sub-dam and revetment are all part of the registration. It is the oldest of the fifteen Arakawa River dams, and its registration number, 07-0084, comes first in the group.

Work began in 1921 and took four years. The dam was rebuilt and strengthened several times, and according to Fukushima Prefecture it reached roughly its present form in 1953.

Why the Jizohara Dam Was Registered

The Jizohara Dam was registered under the criterion for structures that contribute to the historic landscape of the country. The Agency for Cultural Affairs describes it as the first dam built as part of the Abukuma River improvement works, with a core role in the system.

Its position is the point. At the head of the fan, it catches sediment before it spreads across the plain, and whatever gets past heads toward central Fukushima. Erosion control on the Arakawa began here because this is the spot that protects the whole basin.

What to Look For

Look beyond the stone-faced dam to the earth embankments on either side. Rather than closing the whole valley with concrete, the builders extended the line with earthen banks, a design suited to the open ground at the fan's head.

Look downstream as well for the sub-dam, a low weir that absorbs the force of water falling from the main dam and keeps the riverbed below from scouring. The two work as a pair.

Visiting the Jizohara Dam

The Jizohara Dam is a working erosion-control structure. There is no fee; you view it from nearby, and climbing on the dam or going down to the riverbed is not allowed. After rain the river can rise suddenly, so keep away from the banks. Directions are on the Arakawa River Sabo Dams page.

Fukushima City's Arakawa Archives room nearby explains the river's sabo works with photographs and models, and is a good place to start before walking to the other dams.