Gunma Dam

0623-Naramata Dam

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0623-Naramata DamGunma Dam
This article can be read in about 5 minutes to read.

Location: Aza-arai-no-zawa, Fujiwara, Minakami-cho, Tone-gun, Gunma
Date of interview: 2005/06/17

View of the levee from downstream

View of the levee from downstream

As you proceed along the mountain road, a rock-fill dam suddenly appears in front of you. This is the Naramata Dam.

View of the levee from downstream

View of the levee from downstream

We will get even closer. When the huge dike covers your field of vision, you are in a world of amazement. How could such a man-made structure exist so deep in the mountains! Incidentally, the volume of the embankment was the largest in Japan until the Tokuyama Dam was completed. It is now the second largest, but it is so huge that it doesn't matter anymore. Compared to the Tokuyama Dam, where you cannot go directly under the embankment, the Naramata Dam is a more friendly dam.

Temporary drainage tunnel?

Temporary drainage tunnel?

If you look away from the dike to the right, you will see two tunnels. They appear to be temporary drainage tunnels for the dike construction. However, the right side has a fence, so it does not look like a temporary drainage tunnel, but the left side does not have a fence, so it looks like a discharge facility.

Drainage tunnel?

Drainage tunnel?

We approached the tunnel on its left side. There are traces of water flow. There is also an inspection passage attached to the side wall, so there seems to be no doubt that this is a tunnel for some kind of discharge.

View of the levee from just downstream

View of the levee from just downstream

We are getting closer to the levee. The weather is getting dubious, and it is starting to drizzle. It may be the fate of the rain man, or it may be because we are in the mountains, but it is unfortunate because good weather would have been good for taking pictures.

View of the conduit from directly downstream

View of the conduit from directly downstream

It is a long, high, large conduit. It looks like water is flowing, but unfortunately it is not discharging. I have seen photos and videos of the discharge scene, but I would love to see this in person.

View of the dam inscription and gate

View of the dam inscription and gate

Now, we have moved to the top end. From downstream, we move around in a circle. That is how huge this dam is. And the gate is also quite high. The mechanical part of the gate is covered with a dome because the area is also subject to heavy snowfall.

View of the conduit from the top edge

View of the conduit from the top edge

I was looking at it from below earlier, but it is also exceptional to see it from here. I would like to see the water flowing anyway. A huge slide, thinking that it would be painful if I slipped...

Roller gate

Roller gate

Naramata Dam is a rock-fill dam with only one flood discharge gate, a 7.0m x 10.8m roller gate with a 1.5m x 1.0m slide gate built inside the roller gate. The roller gate weighs 58.6 tons and the slide gate weighs 1.6 tons, for a total of 60.2 tons.

Looking up the gate pillar

Looking up the gate pillar

It is quite high.

View of the top edge from the left bank

View of the top edge from the left bank

With old rockfill, the top edge is also covered with gravel, giving the impression that it is somewhat difficult to walk on, but since it has been converted into a tourist area, it is easier to walk on asphalt pavement and blocks.

lip wrap

lip wrap

Riprap arranged in an orderly fashion. How many stones are there?

View of the gate from the top

View of the gate from the top

I turn around and look at the gate. The gate is also huge.

Naramata Dam Exhibition Hall "Hilltop NARAMATA

Naramata Dam Exhibition Hall "Hilltop NARAMATA

This is the "Hilltop NARAMATA", a museum of the Naramata Dam, with an impressive UFO-like disk-shaped building. The back of the building is a souvenir shop, I think. Since we visited the embankment and souvenir shop first, we could not visit Hilltop NARAMATA because it was closing time.

However, there was a man on staff inside who gave us some light information about the catchment area. He was very kind and gave us a very good impression. I would like to return here again.

View of flood discharge

View of flood discharge

The order is a bit backwards, but if you look at the flood discharge, you will see a leftover.... When the water is discharged, it flows with the water and falls down with a "clank clank clank" sound, right? I am sure. Unfortunately, I have only seen it on film...

View of the dam lake from the top

View of the dam lake from the top

The dam lake is now completely shrouded in fog. The rain is getting heavier. On a clear day, the scenery will surely be exhilarating.

View of the control center and the incline from the top

View of the control center and the incline from the top

The control center is located somewhat away from the dike.

View downstream from the top

View downstream from the top

Again we look downstream, this time through riprap. Oh, if only the weather were better...

View of the downstream bank from the left bank

View of the downstream bank from the left bank

The dike and the gate are just huge. There is no other way but to see it in person.

Looking downstream

Looking downstream

Another look downstream. No matter how many times I look, the drizzle never clears.... We can see the place we first saw from downstream. It feels so far away that I realize how huge it is even more.

View of flood discharge

View of flood discharge

It is a pretty cool flood discharge. Simple and rational. Earlier we featured a roller gate with a built-in slide gate as the door body, but the left and right sides of that gate are free overflow type. This is the one that was left behind.

View of the embankment on the lake side of the dam from the left bank

View of the embankment on the lake side of the dam from the left bank

The riprap on this side is also quite beautiful. The rain was getting heavier, so we gave up on further visits. Naramata Dam is one dam I would like to visit again.

dam characteristics

River NameNaramata River, Tone River system
ObjectiveFlood control, agricultural disaster prevention, unspecified water, river maintenance water, and
Irrigation water, water supply water, industrial water, power generation
Modelrockfill
Bank height158m
Bank length520m
Dam volume13,100,000m3
Watershed Area95.1 km2
Reservoir area200 ha
Total storage capacity90,000,000m3
Effective water storage capacity85,000,000m3
Dam operatorPublic corporation for water resources development, one construction
Main body constructorKashima, Kumagaya, Japan Land
Year of launch1973
Year Completed1990
Name of Dam LakeFerruginous Lake

Other facilities/observations

It is definitely a dam you should visit. And I would love to see the discharge scene live.

Parking lot
Toilet
Park
PR Exhibition Hall
Fishing

Accommodations that may be close to Naramata Dam

This article was written by.
Shin Jinma

Dam enthusiast who loves Momosuke Fukuzawa / Dampedia and Dam News administrator / Certified Dammeister (01-018) by the Japan Dam Foundation / Started selling discharge caution goods.https://shop.dampedia.com

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