Know More about Miyagase Dam
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Flow of Dam Operation
Miyagase Dam has four discharge facilities that serve respective functions, and discharges from the dam are effectively conducted through using these facilities according to conditions. Let's take a look at the actual flow of operation of Miyagase Dam to see which facilities are used in what situations.
Normal Times
At normal times, Miyagase Dam conducts discharge mainly for two reasons. The first is when there is not enough water to use in downstream rivers. This is referred to as water utilization discharge. The second type is discharge for generating electricity at the Aikawa Power Station No. 1 located immediately below Miyagase Dam. Moreover, it is necessary to take the river environment into consideration when conducting discharges at normal times. Such discharges are conducted by means of "selective intake facility", which is used according to each situation.
Flood Times
At times of flood, the discharge flow is increased to 100m³ per second. Since the selective intake facility can discharge a maximum of 55m³ per second, the remaining 45m³ per second is discharged from the high-level spillway for normal use. This discharge facility, which is also used for conducting sightseeing discharges, is located in the center of the dam.
Emergency Times
At times of emergency, when even the flood discharge is not enough to keep up with the amount required, discharge in excess of 100m³ per second is sometimes also conducted. In such cases, in addition to the two discharge facilities described above, a low-level spillway for normal use is used to conduct discharge up to a combined possible total of 355m³ per second. Also, in emergency situations where water is almost about to overflow from the dam, there is an emergency spillway near the top of the dam, but this is never used in ordinary circumstances.
