Measures to makeHorikawa River Limpid

Implementation by Nagoya City
Feb.6th 2016
Greenification & PublicWorks Bureau
River Dep. River Plannning Div.
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■ Making additional water sources◆ Use of Shallow Ground Water (in the upper stream)②①①
Sanage Bridge②③④0.01m3/s③0.01m3/s④⑤⑥0.01m3/s

Meijo Park

⑤0.01m3/s⑥Nagoya Castle
0.01m3/s

0.0005m3/s

2

■ Making additional water sources(New project in FY2015)◆ Upstream of Nakatsuchido Bridge
0.01㎥/s water will be lead into from Mar. 2016.
Being built now

Nakatsuchido BridgeMeijo Park

Nagoya Castle3■ Improvement of water quality◆ Removal of sludge

JR、名鉄橋
railways

Oto Bridge
Removedin 2015

SumiyoshiBridge
Removedin 2014

Kameya Bridge

Removedin 20134

■ Improvement of water quality◆ Making slack and rapid current
Setting wooden piles and ripraps bends stream and makes current slack andrapid, which helps self-purification of Horikawa River.
since 2014

fish spawning andplants’ seed ashore

bent stream5■ Improvement of water quality
Since 2010（夫婦橋～黒川１号橋）

Before（2009）

After（2013）

Since 2012（黒川２号橋下流）

Before（2011）◆ Improvement
・Variety and amount of fish
increased.
・Benthos increased.
・Plants grow up more.
Some of the creatures
seen in the upstream of Horikawa River

After（2013）

設置した玉石に群がるオイカワ

Since 2013（黒川２号橋上流）
淵に集まるマガモ

Before（2012）

After（2015）

小魚を採る
コサギ

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■ Improvement of water quality

Meoto Bridge

Set here!
Tsujie Bridge

Kurokawa-daini Bridge

Rurikou Bridge

現在7■ Gojo Bridge River SquareConstruction of River Square by Gojo Bridge
was completed in Nov. 2015 !
The square is equipped with a guideboard about history,
Tuiji-Bei(Japanese traditional wall) and shore forgetting on/off the boats.

Guideboard

Tuiji-Bei Wall

Reuse of the stone pavement

Shore for getting
on/off the boats8■Dredging works in Yada River Inverted Siphon
Shonai River●What is Inverted Siphon？
Yada River

Horikawa
RIver

When a culvert needs to intersect a river,the culvert crosses under the bottom of the river.

Yada River
Inverted Siphon
Sanage Bridge●Cross section of the inverted siphon
Kita Ward

Moriyama Ward

Meijo Park

Yada River

Nagoya Castle

To Kurokawa
Sluiceway

Horikawa River200m9

■Dredging works in Yada River Inverted Siphon●History・１６７６

Yada RiverInverted Siphon

・１８７７
Sanage Bridge

・１９１１・１９５５

It was built to flow water from
Shonai River to Nagoya Castle moat.
(built in wood)
The Kurokawa excavation works wascompleted. The Inverted Siphon
reconstructed for water transport.
Rebuilt with artificial stone
Rebuilt with reinforced concrete（water transport was closed down）●The current structure

Section A-A

２．４ｍ

２．４ｍ

２．５ｍ

Meijo Park

Nagoya Castle
Kita Ward

Yada RiverMoriyama WardＡＡ10

■Dredging works in Yada River Inverted Siphon●State in the culvert①②： Photographing directionKita Ward

Yada RiverMoriyama Ward①②11

■Dredging works in Yada River Inverted Siphon●State in the culvert③④： Photographing direction
Kita Ward

Yada River③Moriyama Ward④12

■Dredging works in Yada River Inverted Siphon
Strong vacuum suction vehicle
used for dredging

The trash which can't becollected by vacuum car
Plastic garbage（Lunch boxes）

WoodchipAluminum can13

■Pollutants removal・inflow reduction◆Advanced water treatment at Meijo Water Treatment Center（Started operation in May, 2010）

mg/l8

Afterintroduction

6

Decreased by 15%

45.524.2

ＢＯＤ
Average 4.7

5.3

4.5

2013

2014

0
2007～
2009

2012

mg/l
43

Filter out more minute2
Suspended Solids(SS) in 1
treated water by filtration 0devices

ＳＳ

Afterintroduction

3.3

Decreased by 60%
Average1.3

2007～
2009

121

2012

2013

2015

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■Pollutants removal/inflow reduction◆Improvement of the combined sewer system(Installation of the garbage removal device)

Number of garbage removal devices
Planned2015
Installedvalue（Estimate）
126

Beforeintroduction

101

10Garbage
removal devices

OverflowToA water treatment center

Afterintroduction

Garbage in treated water
overflow with rainwater
Overflow

Rainwater treated by thegarbage removal devices
overflowTo
A water treatment center

Removed garbage istreated with sewage atwater treatment centers

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■Pollutants removal/inflow reduction◆A Garbage Catcher(Near Johoku Bridge) Introduced in 2006

A garbage basket

An inflow gate

A capturing fence

Setting condition

The accumulation result in 2012〃
in 2013〃in 2014〃in 2015

Cross-section view

1.1tons
0.8tons
0.7tons
1.2tons← As of December 201516

■Pollutants removal/inflow reduction◆Control of combined sewer overflow(Rainwater storage facilities)
Construct rainwater storage facilities to reduce pollution load for
Horikawa River in rainy weather by storing high polluted first flush
rainwater temporarily.
Horikawa Ugan Rain- Horikawa Sagan RainOzone stormwater
water Reservior forwater Reservior forreserviorpollution controll
pollution controll

Started operation in 2006

（12,000ｍ3）

Started operation in 2010

（13,000ｍ3）

Under construction（14,000ｍ3）

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■Secure the river source◆Reclaimed wastewater supply（Except winter）

Use of reclaimed wastewater treated by the membrane
filtration process at Moriyama Water Treatment Center（maximum water supply : 4,000㎥／day （0.046㎥／s））

Moriyama Water
Treatment Center

Flat membrane units
in aerobic tanks(400 sheets×12units)

Shonai irrigation channel

The membrane caseof an upper stage(200cartridges inside)

Horikawa River

The membrane caseof a lower stage(200 cartridges inside)

Flat membrane units※Water conveyance period is generally irrigationseasons (from April to October)(except the period for Shonai irrigation channel(from November to March))18

Thank you foryour kind attention.

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