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160:) mauled the city of Sanriku Takada. The tsunami came over the sand hills and the 3 metres (9.8 ft) high dike, built in 1908, and over the dike of the northern part of the lake into the Kawara River. Low areas of the city were flooded. A 140 metres (460 ft) segment of the dike was destroyed, which formed a water lane for over 200 metres (660 ft) connecting the lake and the sea. Through the efforts of 1,500 soldiers of the
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into the lake at high tide. By the installment of the watergate, the water of the lake became closed and the lake was polluted by the city's waste water. The pollution progressed with the deposition of sludge. Previously swimming was possible, but with increasing pollution, the lake produced an offensive odor. A
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when the sea level rose. Sand was carried from the Kesen River into Hirota Bay. About 7500 years ago, the surface area of the bay grew, thus the present plain was under water. Mud deposited in the
Furukawanuma Lake was formed by the formation of sand hills about 1,000 years ago. There was a 200 to
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In
December 1998, the Kawaharagawa Gate was opened and the water of the lake was mixed with seawater. Sewage from Rikuzen Takada city had been discharged into nearby waterways which fed into the lake, but in 1998, the city constructed a new system for treatment of sewage. Removal of the sludge in
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The first dike was constructed between 1960 and 1963 for the protection of the pine trees. The second dike, 5.5 metres (18 ft) high, was constructed between 1963 and 1966 to protect the city from tsunamis. In 1968, a gate was attached to the water lane of Kesen River to prevent water flowing
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The Kawara River flowed into the lake from the north-west, while the
Koizumi River flowed from the east. The rivers contained particulates that fell to the lake bed beneath. The Kesen River flowed into the lake when there were floods, and the incoming fresh water mixed with sea water. A lock was
179:(the 1960 Chile tsunami), an iron floodgate was installed, and the quality of water in the lake diminished by the flow of waste into the lake. Attempts to purify the water continued. The tsunami in 2011 removed all the sandbanks forming the lake and the lake disappeared.
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in detergents was prohibited. Clean water regulations were established for the lake in 1987. Experts experimented with ways to remove the sludge efficiently with minimum disturbance to water quality. In March 1992, Iwate
Prefecture started to clean the lake.
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In 1982, volunteers from
Rikuzen Takada started a campaign to clean up the lake. The sludge was 2 metres (6 ft 7 in) thick while the lake was 4 to 5 metres (13 to 16 ft) deep. In 1984, they started to clean the lake. In 1985, the use of
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Between 2006 and 2008, investigations were made to reveal the traces of previous tsunami deposits. Traces were found for the tsunamis of 1611, 1933, and 1896, but not of 869. It was concluded that the tsunami of 869 did not arrive at the lake.
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the lake was completed in 2001. Volunteers distributed water cut bags to be used in kitchens. The level of purification reached the standard level (Lake B type). Water fowl returned to the lake.
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300 metres (660 to 980 ft) wide deposition of sand blocking part of the Hirota Bay. Mud was deposited in Hirota Bay which became deeper. Pine trees were planted along the seashore in the
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struck, the resulting tsunami destroyed the sand wall that separated the lake from the sea. The lake's western edge thus became part of the new coastline, and the lake became part of the sea.
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The damage of the city by the tsunamis of 1896 and 1933 was comparatively small because of the pine trees which served as a tide-water control forest. The Chile tsunami (or
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On March 11, 2011, the waves of the tsunami, more than 10 metres (33 ft) high, destroyed two dikes and the sand hills and the lake diminished into the sea.
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era, a tsunami destroyed the pine trees, but the trees acted as a barrier and the city of
Rikuzen Takata was saved from the full impact of the tsunami.
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145:. The Sanriku Coast has many ria coasts which have frequently been shaped by the actions of tsunami. In 1835, during the
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installed to facilitate the transport of boats to and from the ocean, but it did not block all the water from the sea.
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In the 1970s, the quality of water was comparatively high. After the
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493:, Iwate University Department of Agriculture Reports, 1989, 19,2.
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1980, Iwate
University Department of Agriculture Report, 15, 2.
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The Rise of the Sea and
Alluvium in Holocene, in Takata Plane
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Invasions and
Depositions by the Chile Earthquake and Tsunami
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1982, Nihon Dojo Hiryo Gakkai, Koenshu, NAID 110001781378
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Enzo Imano, Shin
Kitamura, Tamio Kodaka, Jun Kataoka,
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Rikuzentakada is the largest alluvial plain along the
136:. The plain started to form at the last stage of the
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Kawara River, Koizumi River, Kesen River, sea water
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491:Studies on the lakes and ponds in Iwate Prefecture
489:Minoru Yoshida, Yoshihiko Wakamatsu, Ayako Chiba,
467:Noboru Chida, Hideaki Matsumoto, Shin-ichi Ohara,
455:Studies on the Lakes and Ponds in Iwate Prefecture
164:, a dike was made between the lake and the lake.
450:1960, Tohoku Chiri, 12, 4, Tohoku Chiri Gakkai.
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407:"津波堆積物調査にもとづく地震発生履歴に関する研究 東北地方太平洋沿岸域における地質調査"
251:"津波堆積物調査にもとづく地震発生履歴に関する研究 東北地方太平洋沿岸域における地質調査"
8:
518:Rikuzen-Takada History Editing Committee,
513:The History of Rikuzen Takada volume 7, ge
511:Rikuzen-Takada History Editing Committee,
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474:Sohei Kaizuka, Hiroshi Naruse, Yoko Ota,
359:Rikuzen Takada History editing committee
305:Rikuzen-Takada History Editing Committee
296:Rikuzen-Takada History Editing Committee
287:Rikuzen-Takada History Editing Committee
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520:The History of Rikuzen Takada,volume 8
476:Nature in Japan, Plains and Seashores
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527:The people who made seashore forests
462:Pollution of Water in Furukawanuma
14:
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460:Minoru Yoshida, Naoto Morioka,
453:Minoru Yoshida, Naoto Morioka,
116:until March 11, 2011. When the
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588:History of Iwate Prefecture
108:was a lake that existed in
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39:Rikuzentakata, Iwate, Japan
16:Former lake in Iwate, Japan
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498:A purified lake comes back
583:Lakes of Iwate Prefecture
471:1984, Tohoku Chiri, 36,4.
378:いわて森・川・海活動事例集 古川沼をきれいにする会
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559:39.008361°N 141.634361°E
404:"東北地方太平洋沿岸域における地質調査">
177:1960 Valdivia earthquake
158:1960 Valdivia earthquake
423:岩手県における被災状況と復興への取組">
248:東北地方太平洋沿岸域における地質調査">
529:2003, Hokuto Shuppan,
478:1985, Iwanami Shoten,
162:Imperial Japanese Army
118:2011 Tohoku earthquake
73:Became part of the sea
564:39.008361; 141.634361
326:"岩手県大船渡地方振興局土木部工務第二課"
593:Former lakes of Asia
426:"岩手県における被災状況と復興への取組"
323:"古川沼をきれいにする取り組み">
110:Rikuzentakata, Iwate
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332:岩手県大船渡地方振興局土木部工務第二課
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547:39°0′30.1″N
49:Former lake
577:Categories
441:References
414:地震調査研究推進本部
259:地震調査研究推進本部
172:occurred.
143:Edo period
218:Footnotes
190:phosphate
381:Archived
170:red tide
36:Location
314:Yoshida
230:Kaizuka
138:ice age
132:of the
124:History
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341:Shishi
522:1999.
515:1996.
429:(PDF)
410:(PDF)
278:Imano
254:(PDF)
239:Senda
147:Tenpo
114:Japan
84:Japan
79:Basin
531:ISBN
502:ISBN
480:ISBN
433:達増拓也
45:Type
269:Oda
130:ria
97:古川沼
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