Measures to make Horikawa River
LimpidImplementation by Nagoya city

Feb.23rd .2013
Nagoya City Greenification &Public Works Bureau
River Dep.River Planning Div.
1

■Reservation of additional water source◆Use of shallow ground wateruse of shallow ground water in the
upstream of Horikawa River

Upstream of Tujie Bridge
Sanage Bridge

Upstream of Kizune Bridge

Simizu-wakuwaku-water

0.01m3/s

0.01m3/s

0.0005m3/s

Meijo Park

Nagoya Castle
Koshio Bridge

Naya Bridge

2

■ Reservation of additional water source（Implementation of this fiscal year 2012）◆ Well Water in Sekotransmitted into Horikawa River (0.01m3/s)

Sanage Bride

Meijo Park

Nagoya Castle
Koshio Bridge
Naya Bridge

3■Improvement of water quality◆Improvement in theself-clarification by changing
monotone straight flow todiversionary flow
with wood piles, stones
and vegetation.

monotone flow
Wood pile

Wood pile
Wood pile
Obstaclestone

diversionary flow

Obstacle
sotne

Image photo4

■Improvement of water quality(Activity in fiscal year 2012)◆Kizune Bridge – Kurokawa No.2 Bridge
Putting stones in the river to change the flow.
Habitats for the living things and Plants were also set
under the stones.

Children also supported the activity.
Piled stones

Fish found in the post-survey

pale chub (fresh water minnow)
U-shaped gutter

PVC pipe

Artificial habitat
Under piled stones
rhinogobius flumineus

5■ Improvement of water quality◆ Removal of sludge

From FY 1994 to 2011

Removed 144,000m3

6

■Removal and inflow reduction of pollutants(Nagoya City Waterworks and Sewerage Bureau)◆Horikawa Sagan Rain-water Reservoir for pollution control (14,000m3)
Now under construction

Tunneling machine is now digging here41

Pit (departure and arrival shaft forthe shield tunneling machine)

Nagoya High Way(Route)Rain-water reservoirs for pollution control areconstructed for storing rainwater temporarily anddecreasing pollution load to be flown into theHorikawa river.
※Stored rainwater is treated at the Meijo
wastewater treatment center after the rain stops.

Shimizu

SugimuraElem. School

Elem. School

OhsugiElem. School

Meijo subway
line

Otsu Street

Stormwater Reservoir

Rain-water Reserviorfor pollution controll

Wall separating Red and Blue zone

7

■Reduction of pollutant（Combined Sewer Overflow Control）◆Garbage removal device
SunnyRainStop garbage from spilling over intoHorikawa River and carrying them towastewater treatment plant

Installation of garbage removal device

8■ Water quality survey with operating gateof Shonai Irrigation Headwork
Mizuwake Bridge

Shonai Irrigation
Headwork

Horikawa River
Motoiri Sluiceway

KitawardMoriyamaward

Hatta River
Shonai River9

■Gate Number

Left Bank①②③④Winch Gate⑤⑥１４

Right Bank（Right Side) 4 tilting gates（Left Side） 6 winch gates

Tilting Gate10２３

■Result of Quality Survey

12108642

Katsunishi Urban
勝西下水出口Drainage Outlet

⑥2/27

①2/16

①2/13

⑥2/09

⑥2/06

①1/30

①1/26

③1/23

⑥1/19

0⑥1/16

Concentration of Lignin mg/l

◆Concentration of Lignin （Jan – Feb 2012）

黒川樋門
Motoiri Sluiceway

Water quality seems better when the Winch Gate① is open

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■Result of Quality Survey

12108642

Katsunishi Urban
勝西下水路出口
Drainage Outlet

①9/10

⑥9/6

⑥8/30

①8/27

①8/9

⑥8/6

0①8/2

Concentration of Lignin mg/l

◆Concentration of Lignin （Aug – Sep 2012）

元杁樋門
Motoiri Sluiceway

The concentration of Lignin does not seem to depend on
which gate is open.

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■The difference between Winter and Summer
WinterSummer

Water quality tends tobe better when a winch
gate near left bank isopen.

Water quality does notseem to depend on
which gate is open.
Mizuwake Bridge

The gap of watertemperature could
cause the different
way of mixture.

Shonai Irrigation Headworks
Horikawa
River
MotoiriSluiceway

Hatta River
Winter ２５℃
Summer ３０℃

Shonai River
Winter １０℃
Summer ３０℃

Hatta
River
ShonaiRiver13

■Monitoring point

Mizuwake Bridge

Winch gate Tilting gate

16

Shonai Irrigation Headworks

Horikawa
RiverMotoiri
Sluiceway

Kita
Ward

MoriyamaWardWater quality of surface andlower layer are surveyed on
the Shonai River.

HattaRiverShonai
RiverKatsunishi
Urban
Drainageoutlet14

■Result of survey（water temperature ℃）
Irrigation Headworks

dateMizuwake Bridge

1Horikawa
River

Open gate No.

2/8
①

2/12
⑥

winch G1

surface 8.5
lower 7.5

surface 4.7
lower 4.6

winch G6

surface 8.0
lower 6.0

surface 15.7
lower 7.9

tilting G

surface 11.5
lower 9.7

surface 15.8
lower 12.2

6 TiltingMotoiriSluiceway

Motoiri Sluiceway（Horikawa River）

2/8
①

2/12
⑥

5.34.0Katsunishi Urban
Drainage outlet

Shonai
River

2/8
①

2/12⑥22.3

23.4

八田川Hatta
River15■Result of survey（the concentration of Lignin)
mg/L
Irrigation Headworks

2/8
①date
Mizuwake Bridge

1Horikawa
River

Open gate No.

winch G1

surface 2.0 surface 1 or lesslower 1.9 lower 1 or lesswinch G6

surface 1.7 surface 5.5
lower 1.5 lower 1.7

tilting G

surface 2.5 surface 4.6
lower 2.2 lower 3.8

6 TiltingMotoiriSluiceway

Motoiri Sluiceway（Hori River）

2/8①2/12⑥

1 or less1 or less2/12⑥

Katsunishi Urban
Drainage outlet

2/8①

2/12⑥

7.3

8.3

八田川
Hatta
ShonaiRiverRiver16

■Relation between COD andthe concentration of Lignin
Ligninリグニン(mg/l)

correlation
between COD and the concentration of Lignin
CODとリグニンの相関

9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0

y = 0.2752x - 0.3275
R² = 0.9207

0.0

10.0

20.0

30.0

40.0

COD(mg/l)

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■Conclusions of the winter survey
・ Both the concentration of Lignin and water temperature aredifferent between surface and lower layer at the confluence of theShonai River and the Hatta River. At that point, water from tworivers sometimes make different layers.
・When the flow volume of the main stream of the Shonai River ismore than some extent, the concentration of Lignin of inflow into
the Horikawa River doesn’t probably increase.
・Because there’s a correlation between the concentration of Lignin
and COD, the volume of inflow from Hatta River can be estimatedby measurement of COD.

About future survey
We’ll make water quality survey focusing on the relation
with water level or flow as well as the gate operation.

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