Technical Tour (Optional)
①Number of participants: 80 (estimated)
③ Means of transportation: Two buses（Group A and Group B）
④ Date and time:
Day 1: June 6, 7:30-19:00
Day 2: June 7, 7:30-19:00
Day 1: （A）Nagoya City➡Koshibu Dam Tour➡(Magomejuku)➡Nagoya City
（B）Nagoya City➡(Magomejuku)➡Koshibu Dam Tour➡Nagoya City
Day 2:（A）Nagoya City➡New Maruyama Dam and Power Plant➡Ena Gorge➡Origawa Dam➡Roadside Station Obaachan-Ichi/Yamaoka➡Nagoya City
（B）Nagoya City➡Origawa Dam➡Roadside Station Obaachan-Ichi/Yamaoka➡Ena Gorge➡New Maruyama Dam and Power Plant➡Nagoya City
Tour Day 1: Koshibu Dam and Sediment Bypass Tunnel
The Tenryu River system is a watershed with extremely high sediment production, and the rapid increase in sedimentation after dam construction, which exceeded expectations, was causing a decline in dam functions.
As a drastic measure against this sedimentation, the Koshibu Dam has installed a sediment bypass tunnel. The sediment such as sand, gravels, and wash-load into the reservoir are bypassed to the downstream of the dam. The sediment bypass tunnel was completed in 2016.
Tour Day 2; Shin Maruyama Dam
(One of the Largest Dam Upgrade Project in Japan)
Shin Maruyama Dam Project was started in 1986. The height of Maruyama Dam rises by 20.2 m. Shin Maruyama Dam will be able to store 3.6 times more water than the Maruyama Dam during a flood event. Of the 72 million m3 flood control capacity, 15 million m3 will be effectively utilized through preliminary releases of unspecified capacity which is set for environmental flow and low flow augmentation.
The axis of the new dam was moved 47.5 m downstream from the existing dam axis, and a special structure was adopted in which the new dam body sits on the downstream face of the existing dam body.