Measures to makeHorikawa River Limpid
Implementation by Nagoya City
Feb.18th 2017

Greenification & PublicWorks Bureau
River Plannning Div.
Waterworks and Sewerage Bureau
Sewerage Plannning Div.
１

Points of the Report
Implemented measures (by Mar.2017)
・Sludge was removed near the pier ofNaya Bridge（Jan.2017）
・Shallows and deeps were made atdownstream of Meoto Bridge（ Jan.2017 ）Planned measures (by Mar.2018)
・Clarification of Horikawa Reverat Gojobashi area
Expansion of covering sand area
（From Habashita Bridge to Nishiki Bridge）
・Measures against stench at
Shin-Horikawa River2

■Removing sludge near the pier of Naya Bridge
Redevelopment project ofNaya Bridge east urban district

HorikawaRever↓↓↓Completion scheduled in Jun, 2017
It is expected that many people will
Gather on this occasion.
Old canal ・ Pier
The width is wider than others,
and sludge tends to be piled up.
Pier

A cross-sectional view

Stench occurs.

Removingsludge
The cross-sectional viewat the old canal and the pierOld canal and pierOld canal

Covering sand3

■Removing sludge at Naya Bridge area
◆Construction appearance〜Removing sludge 〜

Backhoe
PierCarryingearthship

Diffusion prevention fence

Removal amount is about 300m34

■ Removal of Sludge in Naya Bridge area
◆Covered sand〜 Covered sand on the old canal 〜

5■ Removal of Sludge in Naya Bridge area
The last meeting（Experiment in Gojyo Bridge area）
The right bank of the upper stream,
Nala Bridge

Sand

Good condition sandcould be confirmed
at higher bank level.

〜 Covered sand on the old canal 〜
To suppress of sludge redeposition,
we decided to the height of sand making
use of experiment in Gojyo Bridge area.

Appeared on ebb tide
▽Synodic Mean Low Water

Purifyingmaterial6

■ Improvement of water quality◆ Making shallows and deeps
Setting wooden piles and ripraps generates variable stream on the river for enforcing
river s self-purification function with growth of plants.
The place of work years before

fish spawning andplants’ seed ashorechange of stream20

■Improvement of water quality
Installed in 2010
（Meoto Bridge〜Kurokawa No.1 Bridge）

Before（2009）

After（2013）

Installed in 2013
（Upstream of Kurokawa No.2 Bridge）

Before（2012）

After（2015）

Installed in 2012
（Downstream of Kurokawa No.2 Bridge）

Before（2011）

Installed in 2015
（Downstream of Ruriko Bridge）

Before（2015）

Some of the creatures
seen in the upstream of Horikawa River

Pale chubJapanese mitten
crab

After（2016）◆ Improvement
Mallard21

After（2013）

Little egret

・Variety and amount offish have increased.
・Benthos have increased.
・Plants have grow upmore.

Improvement of water quality◆Construction of riffles and pools
At downstream of Meoto Bridge in Kita ward (2016.1 completion)
preconstruction

After construction

We can see a school of fish at the gentle flow9

Improvement of water quality◆Removal of sludge
・Removal of sludge on water route from Shiga Bridge toShin-Horikawa River confluence (1994〜2007)
・Removal of sludge and river bed excavation at theKurokawa
area

Nayabashi
area

OtoBridge

same time implemented from downstream

Now Removing sludge around Oto Bridge
Up to now, removed 150,000m3：現在の断面Sumiyoshi

Dredging of sludge
confluence

Bank protection works
River-bed excavationand Removal of sludge

10

■Making Additional
water sources

H25.3

①

◆Use of shallow ground waterin the upstream area

Seko Bridge
0.01m3/s③

H17.11①②
Sanage Bridge ③④⑤⑥★
⑦⑤H27.3

Shiga Bridge
0.01m3/s⑦H16.10

Tsujie Bridge
0.01m3/s④

Kizune Bridge
0.01m3/s

Meijo PArk

Nagoya Castle

②

H26.3

Sanage Bridge
0.01m3/s⑥

H20.3

Shimizu wakuwaku
0.0005m3/s

H28.3★：Survey point in 2016
（Downstream from Tabata Bridge） Nakatsuchi3Bridge
0.01m /s11

■Implementation to make Horikawa River Limpid
in Gojo Bridge area（Scheduled in 2017）◆Expansion ofcovering sand section

Nagoya Castle

Before experiments

Habashita Bridge

Keiun Bridge
Gojo Bridge

Scheduled construction section
Lentgh：1,100m
Clarification experiments section in 2014
（Gojo Bridge~Naka Bridge）
Length：300m

Naka Bridge
Sakura Bridge

After experiments

Nishiki Bridge
Naya Bridge

Expansion fo covering sand section
from Habashita Bridge to Nishiki Bridge

12

Measures against Smell of Shin Horikawa River(scheduled in FY 2017)

improvement inAn excerpt from report of Horikawa Sen-nin Chosatai

13

Measures against Smell of Shin-Horikawa River(scheduled in FY 2017)
Horidome Water Treatment Center
Shinsuzaki Bridge

Considering of Measures

MukohdaBridgeSumiyoshi Bridge Tateishi Bridge

Hataya Bridge

ShinhoritaBridge

Shiratori Bridge

UchidaBridge
Nagoya Port

Hinode BridgeUkishimaBridge

Survey Work• Surveying to identify the shape of riverbed(Upstream and downstream zone was surveyed in 2016)
Elevation
T.P. (m)
0.0
-1.0
-2.0
-3.0
-4.0
-5.0

Outcomes of Survey in 2016
Miyano-Watashi Port
(River confluence)

-6.0
-7.0

Synodic Mean Low Water (T.P. -1.4)

Shin-Uchida Bridge

Maizuru
BridgeTateishi Bridge

Ukishima Bridge
Uninvestigated Zone

Length of Sedimentary Sludge: about 400m

…Location of Sedimentary Sludge

OoiBridge

Thickness:
About 0.8m

Removal ofSludge

Shin-Horikawa RiverHorikawa River

Ooi Bridge• Considering of effective countermeasures
based on water quality survey and precisesurveyThickness:
About 2m

Maizuru Bridge

Nakagawa Canal

Horidome Water
Treatment Center14

■Removal and reduction of inflow of pollutants◆Advanced water treatment at the Meijo Water
Treatment Center （From May 2010）
mg/l
After introduction

3.3

ＳＳ

Decrease 60％
Average 1.3
2

2007-092013

1120142015

Filter out more minute Suspended Solids(SS)in treated water by filtration devices
15

■Removal and reduction of inflow of pollutants◆Improvement of combined sewer system（Installation of Garbage Removal Device ）The amount of installation of
Garbage Removal DeviceTotal） of plans Installed 2016(planned)

Before126

Water Treatment
Centeroverflow101

11Garbage Removal Device
AfterGarbage in sewage
overflows together
with rainwater

Water Treatment
Centeroverflow

Rainwater treated by thegarbage removal devices
overflow

Removed garbage is treated at
Water Treatment Center
together with sewage

16

■Ｒｅｍｏｖａｌ ａｎｄ ｒｅｄｕｃｔｉｏｎ ｏｆ ｉｎｆｌｏｗ ｏｆ ｐｏｌｌｕｔａｎｔｓ◆Garbage catcher（Near Johoku Bridge) since 2006

garbage basket

Sanage Bridge
inflow gate

capturing fence

Meijo Park

Nagoya Castle

Result of collection in 2013 ０．８ t
Result of collection in 2014 ０．７ t

Koshio Bridge
Naya Bridge

Result of collection in 2015 １．４ t
Result of collection in 2016 １．１ t

At the end of the December

17

■Additional Water Resource◆Utilization of Reclaimed Wastewater(Excluding Winter)
Conducting reclaimed wastewater treated by membrane filtration at theMoriyama Water Treatment Center○ Water Supply： Up to 4,000 /day（0.046 /ｓ）

Moriyama Water
Treatment Center

Flat membrane
unit aerobic tank
(400sheets×12units)

Shonai Irrigation

Upper stage membrane case(200 cartridges inside)
Lower stage membrane caseHorikawa(200 cartridges inside)River※Watering period is almost irrigation period（April〜October）
Flat membrane unit （Except the period for Shonai irrigation channel（Novemver〜March））

18

■Removal and reduction of inflow of pollutants◆Control of combined sewer overflow（rainwater storage facility）
Construct rainwater storage facilities to reduce pollution load for
Horikawa River in rainy weather by storing high polluted first flush
rainwater temporarily.

Ozone Stormwater
Reservoir forpollution control

Started operation in 2006
（12,000ｍ3）

Horikawa Ugan Rainwater Resevoir forpollution control

Horikawa Sagan Rainwater Resevoir forpollution control

Started operation in 2010 Scheduled to start
operation in 2018
（13,000ｍ3）（14,000ｍ3） 19

■Removal and reduction of inflow of pollutants◆Horikawa Ugan
Rain-water Resevoirfor pollution control
・Started operationin September 2010
・About 13,000
Cumulative stored water
volume in fy 2015
About 680,00020