Iwaki River

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Iwaki River
Iwaki River Goshogawara.jpg
Iwaki River, view north from Goshogawara, Aomori Prefecture
Native name岩木川  (Japanese)
Location
Country Japan
Physical characteristics
Source 
  location Shirakami-Sanchi
Mouth  
  location
Japan Sea via Lake Jūsan, Aomori Prefecture
  coordinates
41°01′00″N140°22′00″E / 41.01667°N 140.36667°E / 41.01667; 140.36667 Coordinates: 41°01′00″N140°22′00″E / 41.01667°N 140.36667°E / 41.01667; 140.36667
  elevation
0 m (0 ft)
Length102 km (63 mi)
Basin size2,544 km2 (982 sq mi)

The Iwaki River (岩木川, Iwaki-gawa) is a river that crosses western Aomori Prefecture, Japan. It is 102 kilometers (63 mi) in length and has a drainage area of 2,544 square kilometers (982 sq mi). Under the Rivers Act of 1964 the Iwaki is designated as a Class 1 River and is managed by the Japanese Ministry of Land, Infrastructure, Transport and Tourism. [1] [2] The Iwaki River is the longest river in Aomori Prefecture, and is the source of irrigation for the large-scale rice and apple production of the prefecture. [3] [4] [5] [6] The Iwaki River, in the Tōhoku region north of the Fukushima Daiichi Nuclear Power Plant, remains unpolluted by radioactive materials after the Fukushima Daiichi nuclear disaster. Testing for caesium-134 and caesium-137 is carried out and published on a bimonthly basis. [7]

Contents

Geography

The source of the Iwaki River is at Mount Ganmori (987 metres (3,238 ft)) A in the Shirakami-Sanchi region, a mountainous, unspoiled expanse of virgin forest which spans both Akita and Aomori Prefectures. [5] The river flows eastward as a small mountain stream, [6] then joins several tributaries to form the scenic Meya Ravine. The multi-purpose Meya Dam is located in the upper reaches of the Iwaki River. The river turns sharply northward at the city of Hirosaki. The river crosses the broad Tsugaru Plain, where it is joined by the Aseishi, Hira, and To rivers before emptying into Lake Jūsan on the western coast of the Tsugaru Peninsula. [3] [4] [6] The mouth of the Iwaki River at Lake Jūsan is known as Mitoguchi. [1] [8] Parts of the Iwaki River are protected as part of Towada-Hachimantai National Park, Tsugaru Quasi-National Park, and five prefectural parks. [1] It flows through the following municipalities: Nishimeya, [9] Hirosaki, Fujisaki, Itayanagi, Tsuruta, Tsugaru, Goshogawara, Nakadomari, and Shiura, where it enters Lake Jūsan.

Tributaries

History

Early history

The Iwaki River supported numerous villages as early as the Jōmon period (14,000 300 BCE) as evidenced by numerous shell mounds. The river was revered as the "mother of the Tsugaru Plain" throughout its early history. [6] The Iwaki River region, located in the vast northern Mutsu Province, came under the control of the central government throughout much of the Heian period (794 1185). The Northern Fujiwara clan, based in Hiraizumi in present-day Iwate Prefecture, controlled the rich trade of the Port of Tosa in present-day Goshogawara. Despite the loss of control of much of Japan later in the Heian period, the court maintained some level of military presence in Mutsu. [10] This control ended when the Northern Fujiwara were conquered by Minamoto no Yoritomo (1147 1199) and clans of the Kantō region, and the Iwaki River region came under the direct control of the Kamakura shogunate. By the mid-Kamakura period the Akita clan ruled the area, and the ranches, agriculture of the Iwaki River region, and trade with the Ainu. The Port of Tosa was destroyed in an enormous tsunami in 1340. The Akita clan was eventually defeated by the Nanbu clan during the Sengoku period (14671573). [6] Numerous castles were constructed along the Iwaki River, notably Hirosaki Castle.

Edo period

The Tokugawa shogunate quickly established stability in the Iwaki River region at the beginning of the Edo period (1603 1868). The course of the Iwaki River was diverted and developed for agricultural as part of an effort by the Tokugawa shogunate for the increase of agricultural output across Japan. [6] The original path of the upper reaches of the Iwaki River remains unclear. There were originally two rivers in the area of the castle town of Hirosaki, and at some point in the late 17th century they were diverted into a single river, the Iwaki. [6] The Tsugaru Domain began large-scale work on the Iwaki River in the same period to open new rice paddies on the Tsugaru Plain. The Iwaki River had a lively riverboat trade, and rice storehouses controlled by the Tokugawa shogunate were built in Sanzeji (present-day Akita City), Fujisaki, Itayanoki (present-day Itayanagi), and Kanagi. The rice was collected at the Port of Jūsan in present-day Goshogawara at the mouth of the river at Lake Jūsan. From there the rice was transported to Ajigasawa on the Sea of Japan to be shipped to the Edo capitol. [6]

Modern period

After the Meiji Restoration in 1868 the construction of railroads in Aomori Prefecture, specifically the Ōu Main Line, ended the comparatively inefficient riverboat trade along the Iwaki River in favor of the movement of agricultural cargo by rail. In the 20th century the central government of Japan took direct control of riverworks to prevent flooding on the Iwaki, a chronic problem recorded as early as the Edo period. The Iwaki River Improvement Plan (岩木川改修計画, Iwakigawa Kaishuu Keikaku) was officially approved by the Diet of Japan in 1917. [1] Large-scale flood prevention works began shortly afterwards. The mouth of the river at Lake Jūsan, Mitoguchi, suffered frequent blockage between November and April due to strong winds and waves, a feature of the harsh climate of northern Aomori Prefecture. Projects to remove blockages of the river at Mitoguchi began in the Meiji period, but caused a change in water levels on the upper reaches of the river. The controversy over construction work at Mitoguchi became increasingly controversial, resulting in violent clashes between residents of the upper and lower regions of the Iwaki River in 1890. [1] A pier to prevent blockage was excavated and constructed at the mouth of the river between 1930 and 1946. The passageway allows year round access to the river. [2] [8] Numerous bridges were also constructed across the Iwaki River to improve transportation in Aomori Prefecture. [6]

Use

Iwaki River on the Tsugaru Peninsula TsugaruPeninsulaJpLandsat.jpg
Iwaki River on the Tsugaru Peninsula

The Iwaki River is a major source of water for irrigation. Numerous irrigation canals have been built across the Tsugaru Plain, and the Iwaki supports the paddies for vast production of rice in Aomori Prefecture. [4] The river is called "the mother of Tsugaru" for this reason. [1] Aomori Prefecture is the largest producer of apples in Japan, [11] and the upper zone of the Iwaki River provides irrigation for an extensive network of orchards, especially in the area of Hirosaki City. [3] The commercial fishery of ayu is no longer held on the Iwaki, but its lower reaches and mouth of the river at Mitoguchi are a source of commercial clam production.

Fauna and flora

Upper

The source of the Iwaki, in the Shirakami-Sanchi, is home to large virgin expanses of the buna, Siebold's beech. This area, which is also the source of the Oirase River, is designated a UNESCO World Heritage Site. The upper reaches of the Iwaki are a spawning area of the ayu, also known as the sweetfish, and ugui, the Japanese dace. The area is also known as a home for the kingfisher and the Asian house martin. Tsuruyoshi, a creeping species of the common reed and the branched bur-reed can be found in this area. [1]

Middle

The middle reaches of the river, also home to the apple orchards of Aomori, are noted for long belts of willows. The northern goshawk, the nosuri, a species of the common buzzard, and the black kite have breeding grounds in the area. [1]

Lower

The lower reaches of the Iwaki were once a vast reed bed. Numerous bird species are protected in this area, including the marsh grassbird, also known as the Japanese swamp warbler, and the Japanese reed bunting, both of which are threatened by habitat loss. The mākuosamu and Dytiscidae species of beetles are indigenous to the area. The least weasel, common in other areas of the world, is increasingly rare in the Iwaki River region and may become a protected species. The yamato shijimi, a species of clam used in Japanese cuisine, is common in the brackish area of the mouth of the Iwaki River at Mitoguchi and Lake Jūsan. [1]

Footnote

A. ^ Mount Iwaki (1,624.7 metres (5,330 ft)) is not the source of the Iwaki River. While the mountain and river are located in the Tsugaru region and share a common name, Mount Iwaki is located to the west of the middle reaches of Iwaki River, far north of the source of the river.

Related Research Articles

Aomori Prefecture Prefecture of Japan

Aomori Prefecture is a prefecture of Japan in the Tōhoku region. The prefecture's capital, largest city, and namesake is the city of Aomori. Aomori is the northernmost prefecture on Japan's main island, Honshu, and is bordered by the Pacific Ocean to the east, Iwate Prefecture to the southeast, Akita Prefecture to the southwest, the Sea of Japan to the west, and Hokkaido across the Tsugaru Strait to the north. Aomori Prefecture is the 8th-largest prefecture, with an area of 9,645.64 km2 (3,724.20 sq mi), and the 31st-most populous prefecture, with more than 1.2 million people. Approximately 45 percent of Aomori Prefecture's residents live in its two core cities, Aomori and Hachinohe, which lie on coastal plains. The majority of the prefecture is covered in forested mountain ranges, with population centers occupying valleys and plains. Aomori is the third-most populous prefecture in the Tōhoku region, after Miyagi Prefecture and Fukushima Prefecture. Mount Iwaki, an active stratovolcano, is the prefecture's highest point, at almost 1,624.7 m (5,330 ft).

The Tōhoku region, Northeast region, or Northeast Japan consists of the northeastern portion of Honshu, the largest island of Japan. This traditional region consists of six prefectures (ken): Akita, Aomori, Fukushima, Iwate, Miyagi, and Yamagata.

Hirosaki City in Tōhoku, Japan

Hirosaki is a city located in western Aomori Prefecture, Japan. As of 1 April 2020, the city had an estimated population of 168,739 in 71,716 households, and a population density of 330 persons per km2. The total area of the city is 524.20 square kilometers (202.39 sq mi).

Goshogawara City in Tōhoku, Japan

Goshogawara is a city located in Aomori Prefecture, Japan. As of 31 March 2020, the city had an estimated population of 53,576 in 25,568 households, and a population density of 130 persons per km2. The total area of the city is 404.18 square kilometres (156.05 sq mi).

Ajigasawa, Aomori Town in Tōhoku, Japan

Ajigasawa is a town located in Aomori Prefecture, Japan. As of 31 March 2020, the town had an estimated population of 9,613 in 4542 households, and a population density of 28 persons per km2. The total area of the town is 343.08 square kilometres (132.46 sq mi).

Nishimeya Village in Tōhoku, Japan

Nishimeya is a village located in Aomori Prefecture, Japan. As of 1 April 2020, the village had an estimated population of 1340 in 556 households, and a population density of 5.4 persons per km2. The total area of the village is 246.02 square kilometres (94.99 sq mi).

Itayanagi, Aomori Town in Tōhoku, Japan

Itayanagi is a town located in Aomori Prefecture, Japan. As of 1 April 2020, the town had an estimated population of 13,332 in 5450 households, and a population density of 320 persons per km². The total area of the town is 41.88 square kilometres (16.17 sq mi).

Kanagi, Aomori Former municipality in Tōhoku, Japan

Kanagi was a town located in Kitatsugaru District in western Aomori Prefecture, Japan.

Tsuruta is a town located in Aomori Prefecture, Japan. As of 31 March 2019, the town had an estimated population of 12,870 in 5,399 households, and a population density of 280 persons per km2. The total area of the town is 46.4 square kilometres (17.9 sq mi). The name "Tsuruta" is a combination of the character for crane (鶴) with that for rice field (田).

Shiura, Aomori Former municipality in Tōhoku, Japan

Shiura was a village located in Kitatsugaru District in western Aomori Prefecture, Japan.

Iwaki (岩城磐城) may refer to:

Tsugaru, Aomori City in Tōhoku, Japan

Tsugaru is a city located in Aomori Prefecture, Japan. As of 1 April 2020, the city had an estimated population of 31,723 in 13,570 households, and a population density of 130 persons per km². The total area of the city is 253.55 square kilometres (97.90 sq mi). The city's name is atypical for a Japanese place, in that it is written in hiragana rather than kanji.

Hirakawa, Aomori City in Tōhoku, Japan

Hirakawa is a city located in Aomori Prefecture, Japan. As of 31 March 2020, the city had an estimated population of 30,938 in 12,051 households, and a population density of 89 persons per km2. The total area of the city is 346.01 square kilometres (133.60 sq mi).

Mount Iwaki Stratovolcano in Aomori Prefecture, Japan

Mount Iwaki is a stratovolcano located in western Aomori Prefecture, Tohoku, Japan. It is also referred to as Tsugaru Fuji (津軽富士) and less frequently, Okufuji (奥富士) due to its similar shape to Mount Fuji. With a summit elevation of 1,625 meters (5,331 ft) and a prominence of 1,322 meters (4,337 ft) it is the highest mountain in Aomori Prefecture.

National Route 101 is a national highway of Japan connecting the capitals of Aomori and Akita prefectures, Aomori and Akita in northern Japan, with a total length of 241.6 kilometers (150.1 mi). The majority of the highway travels along the coast of the Sea of Japan, paralleling the more inland National Route 7. The present-day highway largely follows the path of the Ōmagoe-kaidō, an Edo period road that linked the Kubota and Hirosaki feudal domains.

National Route 339 is a national highway of Japan that traverses the western side of Aomori Prefecture, traveling south to north. The 108.4-kilometer (67.4 mi) highway begins as a concurrent route with National Route 7 in central Hirosaki, it then leaves National Route 7 in Fujisaki and travels north through the municipalities of Itayanagi, Tsuruta, Goshogawara, and Nakadomari before ending at an intersection with National Route 280 in Sotogahama. In a unique feature, a 0.4-kilometer-long (0.25 mi) section of the route on Cape Tappi is a staircase.

Sendai River

The Sendai River is a river in eastern Tottori Prefecture, Japan. The Sendai is 52 kilometers (32 mi) in length and has a drainage area of 1,190 square kilometers (460 sq mi). The source of the river is in the Chūgoku Mountains. The Sendai flows north through Tottori Prefecture into the Sea of Japan. Under the Rivers Act of 1964 it is designated a Class 1 River, and is managed by the Japanese Ministry of Land, Infrastructure, Transport and Tourism. About 200,000 people live along the course of the river. The Sendai River provides sediment to form the Tottori Sand Dunes, the largest dune system in Japan.

Tsugaru Iwaki Skyline

The Tsugaru Iwaki Skyline is a toll road managed and operated by Iwaki Skyline Co., Ltd. in Hirosaki, Japan. It partially ascends Mount Iwaki and is notable for its steep gradient and 69 hairpin turns, which make it considered as one of the most dangerous mountain roads in the world.

Lake Jūsan Lake in Japan

Lake Jūsan, also known locally as Jūsan Lagoon is a brackish-water lagoon-type estuary located in the city of Goshogawara in Aomori Prefecture, Japan. It is the third-largest lake in Aomori Prefecture, after Lake Towada and Lake Ogawara, with a shoreline of 30 kilometers (19 mi) and a maximum depth of 3 meters.

Sannobō Site

Sannobō ruins is an archaeological site in what is now the city of Goshogawara, Aomori Prefecture, in the Tōhoku region of northern Japan containing the ruins of a Muromachi period Buddhist temple. The remains were designated a National Historic Site in 2017 by the Japanese government.

References

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