Somatani Sabo Dam

A Pioneering Slit Dam on the Somatani Stream

The Somatani Sabo Dam (杣谷堰堤) is an erosion-control (sabo) dam in the Rokko mountains of 1956 in Oishi, Nada Ward, Kobe City, Hyogo Prefecture, and was registered as a Registered Tangible Cultural Property (structure) on October 7, 2014 (Agency for Cultural Affairs).

The Agency records a gravity concrete dam 78 metres long and 16 metres high; registration number 28-0594.

A Sabo Dam with a Slit in Its Spillway

The Somatani Sabo Dam stands on the middle reaches of the Somatani stream in the Toga River system; it is a gravity concrete erosion-control dam with cut granite on its crest and drain holes (Agency for Cultural Affairs).

To regulate the sediment it holds, it has a slit in the middle of its spillway in place of a large culvert at the base, a pioneering design (Agency for Cultural Affairs). According to the Rokko Sabo Office of the Ministry of Land, Infrastructure, Transport and Tourism, it was completed in March 1956 and is regarded as the first slit-type sabo dam in the Rokko mountains and in Japan. A slit dam holds back debris flows and then lets the sediment out little by little in ordinary floods, restoring its capacity; Somatani was built to test how well this worked.

Why It Was Registered

The Agency registered the dam as a model of design. The Gosuke Sabo Dam on the Sumiyoshi River was registered on the same day (Rokko Sabo Office).

What to Look For

Look for the slit in the middle of the spillway and the cut granite on the crest and drain holes (Agency for Cultural Affairs).

Visiting

It is owned by the State (Ministry of Land, Infrastructure, Transport and Tourism) (Agency for Cultural Affairs). No official visiting information was found.