From ancient times, the Japanese people have been familiar with irrigation, water supply and flood control facilities. Rice cultivation was introduced to Japan around the 10th century BC. The earliest rice paddies with civil engineering facilities can be found in south-west of Japan. In the 6th century, the Emperor at that time established centralized government. He prepared irrigation systems for paddies and allocated a certain area of paddy to farmers. A certain portion of the harvest was collected as tax. Sayama-ike, an oldest earth-fill dam for irrigation still in use today, was built in the early 7th century.
In the 20th century, many large dams for flood control and hydropower have been constructed in the central highland, as there are high mountain peaks of over 3,000 meters in elevation and many steep swift-flowing rivers.
In 1950, Japan’s first modern rock-fill dam for hydropower in the central highland, Miboro Dam (H=131m) was planned. The project faced with fierce local opposition to construction. The president of the state-owned hydropower company negotiated earnestly, politely, and in good faith with the residents of the proposed submerged area, and after more than 7 years negotiation, finally it reached a settlement on the relocation.
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