Seawalls of Japan – Erosion

In January we visited a few large seawall structures around the Karakuwa peninsula, one of them in Okabe.

The structure here is 11.3m tall and constructed out of large concrete tiles over a sub structre of rubble/ rocks. What I observed on the structure in late January was early stages of the sub layers of rubble being eroded on the lower side of the structure near the water edge.  Some of the tiles were sitting on just a few remaining rocks with large parts of the substructure missing. Unfortunately I did not photograph the view into the hollow structure.

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Small area of damage, tiles sinking. Possibly due to erosion of sub-material. Photo January 31 2016
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Detail of concrete tile structure at Okabe.

Eroding substructures are pointing to the maintenance issue of these large structures. At present it is unclear how the walls are being maintained and how the associated cost of maintenance will be managed.

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Photo by Masahito Abe, March 2016
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Photo by Masahito Abe, March 2016

 

 

 

 

Seawalls of Japan – Sunago

Site visit with Barbara Hartley, Akihiro Nakamura and guide Keiko Sugawara on 31.01.2016

The seawall here is 11.3 m high. [T.P +11.3] behind the wall structure a small dirt road and no buildings.

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Sunago bay with seawall
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Sunago – Buildings are located on the slope
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Sunago behind the wall

loaction seawall sunago

Location 38.907106, 141.651835

 

In 2012 and 2013 we stayed in the small pension Sunago with the RMIT University and Melbourne University Landscape Architecture study tour students.

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Sunago 2013
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Sunago 2013
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Australian Students swimming at Sunago in summer 2013

 

 

 

Seawalls of Japan – Okabe Karakuwa

Site visit with Barbara Hartley, Akihiro Nakamura and guide Keiko Sugawara on 31.01.2016

The Seawall is 11.3m tall. [T.P+11.3m], the building behind is a sewage treatment facility. Keiko explained that the water in this small bay is brackish due to a number of small steams running into the sea here.

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Okabe Seawall
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Okabe Seawall – Former brackish water area
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Okabe Seawall
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Okabe Seawall
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Okabe Seawall
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Okabe Seawall
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Okabe Seawall
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Okabe Seawall

Seawalls of Japan – Koizumi

Site visit with Barbara Hartley, Akihiro Nakamura and guides Keiko Sugawara and Abe San on 01.02.2016

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Koizumi Seawall T.P. 14.5m
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Koizumi Seawall T.P. 14.5m
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Marker at T.P. +5.0
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Local information board
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Local information booth with scale model
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View across the river estuary

 

note: this structure of 14.5m height is expected to cost 360 billion yen. Further, I learned today, that no dwellings will be situated behind the wall, as all are already located on higher ground.

Shunsuke Hirose offers a very beautiful, ecologically, economically viable alternative here.

1239054_223902847764358_1704967842_n15283958_727443977406475_3623167851202685981_nImages photographed at Information center at Koizumi Beach in November 2016.