Know More about Miyagase Dam
-
Introducing Facilities Inside the Dam
Selective intake facility
External view of selective intake facility
Mechanism of selective water intake
In dam reservoirs such as Miyagase Reservoir, warm water accumulates near the surface, while cold water gathers at the bottom. Moreover, water that has temporarily become turbid due to heavy rain and so on, sometimes flows in around the surface of the dam water. Selective water intake refers to the process of appropriately taking water of differing temperature and turbidity at different depths according to the environment and purpose of use in the lower reaches.
At Miyagase Dam, a selective intake facility is installed. This makes it possible to adjust water intake positions in the reservoir so that clear water with appropriate temperature is discharged, thereby ensuring that impacts on the natural ecosystem in downstream rivers caused by different water temperature and turbidity are kept to a minimum.
The selective intake facility uses the largest gate at Miyagase Dam. This is installed in the center on the upstream side of the dam body. This can take in up to 55m³ (Note 2) per second of water at an optional water level between EL.286m~218m (Note 1).
(Note 1) EL: Elevation
(Note 2) Reference value: A 25m swimming pool at an elementary school has capacity of 375m³Used at Such Times
Selective intake facility
At normal times, water acquired through the selective intake facility is discharged downstream. When we talk about dam water discharge, one often imagines water being discharged from the front of the dam body like in sightseeing discharge, however, usually water is discharged through underground discharge pipes into the downstream. Also, Aikawa Power Station No. 1 uses water that has been acquired from the selective intake facility.
Selective intake facility seen from inside the water intake tower
Water flows downstream through a pipe-shaped intake gate that is erected like a telescope on the inner side of the pillars and screen to ensure that garbage is not let in. If the round float in the center of the photograph can be seen on the reservoir surface, this means that water is being taken from close to the surface.
Reel and wire
A number of large-size winches are installed for moving up and down the water intake gate of the selective intake facility, which weighs hundreds of tons.
Water utilization discharge facility
The water that doesn't pass through Aikawa Power Station No. 1 is discharged from this water utilization discharge facility.