Date of interview: Saturday, March 1, 2014
From Shingu Dam, we came via National Route 319, which runs along the reservoir, to Yanase Dam, which is located upstream. In Shikoku, there is a dam in Tokushima, which is pronounced "Yanase," which is also written as "Uryase," so it is often a question of "which is which" when you say it verbally. It is often asked "which one is it?
Incidentally, National Route 319 is quite narrow and winding, so care should be taken when traveling on it.
Yanase Dam Management Branch Office
Yanase Dam has been managed by the Ministry of Land, Infrastructure, Transport and Tourism, but will be entrusted to the Japan Water Agency in 2021. Therefore, in 2014, it was the Yanase Dam Management Branch Office as shown in the photo below, but now it is the Yanase Dam Management Office Building.
Since the Shingu Dam, managed by the Japan Water Agency, is located downstream of the Yanase Dam, and the Tomigo Dam, also managed by the Agency, is located upstream of the Yanase Dam, it was probably inevitable that the Ministry of Land, Infrastructure, Transport and Tourism would entrust the management of the Yanase Dam, which lies between the two dams, to the Japan Water Agency in terms of operational efficiency and rationalization.
The function of the Doyama River Dam in pictures
This diagram clearly shows the location and roles of Shingu Dam, Yanase Dam, and Tomisato Dam. It is interesting that flood control is depicted in cross section below. It is drawn like a tsunami, but this image is probably created to convey the horror of flooding and the sense of security provided by flood control.
View of the levee from the high ground on the right bank
The right bank, where the control center is located, is elevated and provides a bird's eye view of the Yanase Dam. The crest gate is a steel roller gate with a height of 9.00 m and a width of 10.625 m, consisting of four gates. Although it is difficult to see in the photo below, the left bank of the dam is closer to the left bank.conduitOne 0.8x0.8m high-pressure slide valve is installed as a discharge valve at the bedding height of EL.254.55m.
slab with a haiku cut on it
The bird of prey (特鳥): a bird of prey (時鳥)
A haiku monument has been erected by the administration office overlooking the embankment. The sound of the dynamic discharge of water from the crest gate seems to be transmitted along with the chirping of the cuckoo birds. The author of the haiku is Sakai Mokuzen, former director of the Japan Red Cross Matsuyama Hospital, and there is a monument to his haiku at the Kanomori Dam.
View of the reservoir from the high ground on the right bank
The time was only 8 o'clock. Morning mist or clouds were still covering the sky. Unlike the Shingu Dam, the reservoir has a name: Lake Kinshako. The name comes from the fact that gold sand was extracted from the Dosan River during the Asuka period (710-794).
Square on the right bank
There is a small plaza with a pavilion halfway up the right bank of the landslide. There is a restroom in the back, which now appears to be new and has been replaced as a bio-toilet. The signboard in the back on the right hand side shows in considerable detail the specifications, construction history, water storage capacity distribution map, and drawings.
Mystery Building
We have descended to the top edge level. Two mysterious buildings stand side by side on the right bank. The new building in the foreground is probably an electrical facility.
Remains of the construction
The austere building in the back of the building looks like the remains of a plant used during the construction of the Yanase Dam. It seems to be still in use without being demolished, but it may be used for storage.
View of the top edge from the right bank
The top of the dam was completed in 1953, so it has a rather quaint appearance. The cranked top at the gate pier is somewhat similar to gravity concrete dams of the same age, such as the Maruyama Dam (Gifu Prefecture).
Yanase Dam nameplate
YanagisseeweirThe name plate is engraved with "瀨" (瀨). The use of the old Chinese character "瀨" instead of "se" is also nice.
Looking downstream from the left bank
The austerity of the embankment has appeared on the concrete surface of the embankment over the years. In the photo below, you can see downstream, but unfortunately there is no road, so you cannot look up at the levee from downstream.
View of the right bank from the top
Part of the dam site on the right bank was covered with staircases. As a result of the decision to leave the construction plant in place, it may have been unavoidable that a pathway for management could not be secured and the site had to be covered with a gallery.
Nice gate operation room
The gate operation room has a nice rounded design with corners removed.
The gate operation room on the other side of it
Unfortunately, however, not all of the gate operation rooms were, and three of the five had been updated to prefabricated types like the one in the photo below.
Gate peer
And the distinctive gate pier. The holes are drilled as if they were made by a meat-punching process. Is it constructed in this way to save concrete like a hollow gravity concrete dam? There is a gate operation room at the back of the pier, but the passage and door are narrow. It must have been quite difficult to lay the cables along with the racks in the hole in the middle.
Incidentally, the area that is now the gate operation room used to have only one terrace from which one could look downstream.
Looking downstream from the top
The older gate operation room is rounded, and the gate piers that rise from its lower part and conduit also have an overall rounded design that gives a soft impression.
Looking downstream from the left bank
Parts of it are mossy, and the rough concrete surface gives the appearance of age.
Water use sign on left bank
I don't think I have ever seen such an orderly arrangement of water use signs. It might be better to have them all in one place rather than all over the place, so that it is easier to understand what role the dam plays.
View of the top edge from the left bank
It is a pleasure to be able to enter the top end. Automobiles are of course not allowed.
View of the upstream face of the levee and the reservoir from the left bank
The surface of the lake is quiet. Two intake towers can be seen on the opposite shore. The intake tower on the right is for power generation and feeds water to the Copper River No. 2 Power Plant, which generates up to 2,600 kW of electricity.
The intake tower on the left side feeds water through an underground tunnel in the Hoho Mountains to the Dosan River No. 1 Power Plant in the Uma district, which produces up to 14,300 kW of electricity from Units 1 and 2 combined. The water used at this power plant is also used for water supply, irrigation, and industrial use, so the underground tunnel is called a diversion tunnel.
Shingu DamAs mentioned on the page of the "Shikoku Chuo City Uma Area", it has been a long-cherished wish of the people of the Uma area of Shikokuchuo City since the Edo period to divert and utilize the Doyama River. After many years, this long-cherished wish was fulfilled in October 1953.
Tennis court on the right bank
We are now back on the right bank. Tennis courts at a dam under direct control seem to be a bit unusual, but it seems that they have long since fallen into disuse. I think they were installed for the welfare of the employees and to promote their health, but I often see abandoned tennis courts here and there at dams, perhaps because people don't like to be told they are playing, or because they can no longer afford to play tennis during their breaks due to personnel cutbacks.
Looking upstream from the right bank
Traces of the highest normal water level are clearly visible. The river is responsible not only for water utilization but also for flood control, so it may be said that it has fought many battles.
View of the reservoir from the right bank
The water of the Doyama River, which has been the long-cherished wish of the people of the Uma area of Shikokuchuo City, will be filled with water and delivered to the area for many years to come.
Yanase Dam Specifications
Although Ehime Prefecture is listed as the dam operator, at the time of construction, the Ministry of Construction (now the Shikoku Regional Development Bureau of the Ministry of Land, Infrastructure, Transport and Tourism) was commissioned by Ehime Prefecture to carry out the project.
Location | Ogawayama, Kanasago-cho, Shikokuchuo City, Ehime Prefecture |
River Name | Yoshino River System Doyama River |
Objective | F (flood control, agricultural disaster prevention) A (irrigation water) W(Water for water supply) I (industrial water) P(Power generation) |
Model | G(gravity-fed concrete dam) |
Bank height | 55.5m |
Bank length | 140.7m |
Dam volume | 131,000 m3 |
Watershed Area | 170.7 km2 (direct: 69.5 km2, indirect: 101 km2) |
Reservoir area | 155ha |
Total storage capacity | 32,200,000 m3 |
Effective water storage capacity | 29,600,000 m3 |
Dam operator | Ehime prefecture (Shikoku) |
Main body constructor | Kajima Construction |
Year of launch | 1948 |
Year Completed | 1953. |
Name of Dam Lake | Lake Kinshako |
Other facilities/observations
The reservoir, Golden Sand Lake, is said to be a bass fishing spot, but fishing is prohibited just downstream of the bank and upstream to the netting area.
Parking lot | ○ |
Toilet | ○ |
Park | × |
PR Exhibition Hall | × |
Fishing | ○○ (excluding no-take zones) |
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