Know More about Miyagase Dam
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Introducing Facilities Inside the Dam
High-level spillway for normal use
Sightseeing discharge from the high-level spillway for normal use
The high-level spillway for normal use is the gate that is installed on Miyagase Dam at EL. 235m (Note 1: Intake port).
Situated midway along two discharge pipelines that vertically pass through the dam body, this facility is capable of discharging a maximum of 100m³ (Note 2) of water per second through a single discharge pipe.(Note 1) EL: Elevation
(Note 2): Reference value: A 25m swimming pool at an elementary school has capacity of 375m³Used at Such Times
High-level spillway for normal use
The high-level spillway for normal use is intended to conduct flood control (Note 3).
Miyagase Dam can increase the discharge flow up to 100m³ per second at times of flooding and so on (it can also discharge more than 100m³ per second in emergencies), however, in such cases, flow is regulated so that the selective intake facility conducts maximum water intake of 55m³/s and the high-level spillway for normal use discharges 45m³/s, leading to a combined discharge flow of 100m³/s.
This facility is also used to conduct sightseeing discharge. Normally, discharge is not conducted through simultaneously opening two gates as in the case of sightseeing discharge, and one of the gates is mainly used as preliminary equipment for conducting flood control.(Note 3) Flood control: One of Miyagase Dam's functions. This refers to the function of temporarily holding heavy rains caused by typhoon, etc. and conducting safe discharge to the lower reaches.
The Power to Stop Water: "Hydraulic Cylinders"
Strong stainless steel doors capable of withstanding the dam water pressure are moved up and down by hydraulic power to trigger and stop the flow of water through the pipelines. Each discharge pipe is equipped with a main and secondary door in case of failure, but usually only the main gate is used.