Horikawa Sen-nin Chosatai 2010 （HSC)

Summary meeting for the 23rd stage

The secretariat of Horikawa Sen-nin Chosatai 2010
Sep.29th.2018

Place：
Nagoya Urban InstituteConference room (11th floor)

Photos：The secretariat of
Goyousui-ato-gaien-aigokai
Survey Group1

1. Horikawa Sen-nin Chosatai 2010nd

formation of HSC (April.22 .2007)〜Transmission of Raw Water from The
With a viewpoint and a sence of citizens, the survey of theKiso Riveｒ〜
clarification effect of TRWKR started

1.Purpose
To verify the clarification effects of TRWKR with citizens(1)Develop to new clarifying measures(2)Asses the influence on an ecosystem(3)Sustain and enhance citizens activities(4)Develop citizens awareness in the entire
Horikawa River basin

2.Water source and Volume oftransmission of raw water(1)Water Source : Kiso River(2)Volume of transmission of raw water : Maximum 0.4 m3/s

■ The survey from a viewpoint and a sence of citizens＊Clearness ＊Transparency ＊Color ＊Bubble ＊Smell＊Garbage ＊Living things, etc

3.Pilot project period(1)Evaluation and Survey term : About 5 years（from Apr.2007 to Mar.2012）(Including the term of follow-up survey and evaluation after
the stop of TRWKR)(2)TRWKR period : about 3 years(from Apr.22nd.2007 to Mar.22nd.2010)■Increase of Transmisson Volume from the Shonai River(additional pilot project）
1.Water source and Volume of transmission of raw water

The first Nagoya City Environmental Practice Prize, February.2012
Branch of contribution for Regional Environment Development Award
for Excellence(1)Water Source : Shonai River(2)Transmission Usual 0.4m3/sec (maxium 0.7m3/sec)

2.Period of Increase(1)Experiment Period ： Oct.1st - Dec.31st.2010(2)Period of Increased Transmision Volume : Oct.5th - Nov.2nd.2010

Water Resource Contributor Awards
Minister of Land, infrastructure and Transportation) Aug.20162

Transmission of Raw Water from Kiso River
3 years from April.22nd.2007（Stopped on March.22nd.2010）
To verify the clarification effects of TRWKR
Surveys during TRWKR period :April.2007 〜 March.2010
Surveys after the stop of TRWKR period :April.2010 〜 March.2012

Horikawa Sen-nin Chosatai
April.2007 〜 March.2012■ Fixed Point Observation Groups
Surveying effects of TRWKR■ Free Survey Groups Researching
Horikawa River by free themes■ Horikawa Cheering Groups Cheering
clarification of Horikawa

The survey froma viewpoint and asence of citizens

Results of pilot project (Clarification effects of TRWKR)■ It was confirmed that the water quality tended to improve
during TRWKR between Sanage Bridge and Matsushige
Bridge.
■ Network of citizens who wish for clarification andrestoration of Horikawa River expanded.
■ Citizens awareness of cleaning of the river wasdeveloped.

■ Role of Horikawa Sen-nin Chosatai(Conclusions of Summary Meeting for the 10th Stage)① More surveys should be implemented.
・Continuity of investigation, clarification of thesituation of the river, identification of cause ofpollution in the river, are needed.
・We improve our plan and take action against
the pollution.
・After that, citizens and public administration
do what is possible to clean the river.

②There are many things that citizens
can do.
・We expand our partners who love
Horikawa River and hope TRWKR again.
・We deepen exchanges with people
living in the basin of Kiso, Nagara, and Ibi
River.
・We check the effects of pollution
removal from domestic wastewater andimplement it in each house.

3

Water Environment of Horikawa River
Area of basin: 51.9km2
Length: 16.2km(Tidal effect section 13.6km)

Change in temperature, precipitationand hours of sunshine
Cause of breedingofpphytoplankton,
nitorogen andphosphorus areincluded inwastewater fromhouses, factories
andstores.

The primary cause of water pollution is wastewater from houses, factories, and stores.
Wastewater is discharged after treatment in wastewater treatment plant.
●●●

After heavy rain, wastewater isdischarged without treatment.

It has looked like redtide or blue tide.
In Nagoya Port anddownstream ofHorikawa, it is said
that phytoplankton
does over breedingand extinction, so
water basin is polluted
Red Tide

Kiso River is our water source.

●●●●●● ●●●●●●

Shonai River
Privisional raw watertransmission: 0.3m3/s

●●●

●●●

●●●

Wastewater
Treatment Plant

Tide Gate

Sanage Bridge

Motoiri Sluiceway▼High Tide Horikawa River
Difference of water level is more than 2m between
high tide and ebb tide.
Water level, direction of current and velocity are changed, by tide.

▼Ebb Tide

Nagoya Port

Shimizu wakuwaku-sui

Groundwater, etc

RisingIse Bay
Blue Tide

Sludge rises and floats.

Floating Sludge

Raised Sludge

4Observation method at fixed-point
Measurement of Transparency
Transparency
Meter
100cm
Photo: Shinko Survey Group

What is yourimpression of…
Clearness?
Transparency?
Color? Bubbles?
Smell? Garbage?
Living things?

Measurement of COD
COD: Chemical Oxygen DemandThis is an index of water contamination
used for sea, lakes, and marshes.
It is an oxygen consumption required foroxidation of organic matters dissolved inample water.
The higher COD, the more it iscontaminated.

COD Pack Test

ゆりの会調査隊

5

2．Number of Participants ofHorikawa Sen-nin Chosatai(Horikawa Sen-nin Chosatai started
accepting participation on 26th Mar.2007)

Investigation spots

Network of citizens who wish for clarification
and restoration of Horikawa River is growing.

More than 50 thousand citizens network
Horikawa, the Mother River of Nagoya, was polluted in rapid economic growth..
The citizens have rised to get the past back.
名古屋駅

Start

Now

22nd Apr.2007

29th Sep.2018

Fixed Point
Observation
Groups55 groups
497 persons

101 groups
1,010persons

Free Survey
Groups

22 groups
234 persons

40 groups
650 persons

Horikawa
Cheering
Groups

88 groups
1,531 persons

2,596 groups
51,847 persons

Total

165 groups
2,262 persons

2,737 groups
53,507 persons

6

Number of Participants
Number of Participants in 3 classes
60,000

FPOG

FSG

HCG

total

55,00050,000
Fixed Point Observation Group (FPOG) 1,010

45,000Free Survey Groups (FSG)

40,000Horikawa Cheering Groups (HCG)

35,000total

30,00051,84753,50725,00020,000

第1st

第6st

第4st

第2st

第5st

第3st

◆ Fixed Point Survey Groupsurveying on the fixed points◆ Free theme Survey Groupsurveying on free themes◆ Horikawa Cheering Groupsupporting clarification of Horikawa

650

第10st

第8st
第9st

第7st

第14st

第12st
第11st

第13st

第18st

第16st

第15st

第20st

第19st

第17st

第24st

第22st

第23st

第21st

15,00010,0005,000

As of Sep. 29th, 20182018/122018/8

2018/42017/122017/82017/4

2016/122016/8

2016/4

2015/122015/8

2015/4

2014/12

2014/8

2014/42013/122013/82013/4

2012/122012/8

2012/4

2011/122011/8

2011/4

2010/122010/8

2010/4

2009/12

2009/8

2009/4

2008/12

2008/8

2008/4

2007/12

2007/8

2007/40

7

3. Survey Periods and Number of Reports
Survey Period
Utilization ofshallow
groundwater
At upstream fo
Kitashimizu bridge

With TRWKR

Introduction of advanced
water treatment
at the Meijo Water Treatment Center
Increase of Transmission
Volume fromthe Shonai River

In-service of Horikawa
Ugan Rain-Water
Reservoir for pollution control
Utilization ofreclamed wastwaterfrom Moriyama
Water Treatment
Center from Apr. to
Oct.
At upstream of
Seko Bridge

At upstream of
Sanage Bridge
Covered sandAt upstream of
Shiga Bridge
At upstream of
Nakatodo Bridge

1st stageinterval
2nd stageinterval
3rd stageinterval
4th stageinterval
5th stageinterval
6th stageinterval
7th stageinterval
8th stageinterval
9th stageinterval
10th stage
interval
11th stage
interval
12th stage
interval
13th stage
interval
14th stage
interval
15th stage
interval
16th stage
interval
17th stage
interval
18th stage
interval
19th stage
interval
20th stage

total

Horikawa
River

Shin-Horikawa
River

258
134
383
103
245
64
152
100
145
54
120
81
111
44
104
72
112
42
133
77
148
60
139
92
145
70
113
79
133
91
99
107
113
81
126
91
127
62
130

258
134
383
103
245
64
152
100
145
54
120
81
111
44
104
72
112
42
133
77
148
59
135
78
129
55
99
68
117
78
90
89
100
69
109
79
116
54
107

1
4
14
16
15
14
11
16
13
9
18
13
12
17
12
11
8
23

104
129
58

20
29
10
28
13

22nd stage

Spring〜Early summer/Apr.22nd〜Jun.30th.2007
Jul.1st〜Sep.7th.2007
Autumn〜Early Winter/Sep.8th〜Dec.16th.2007
Dec.17th.2007〜Mar.31st.2008
Spring〜Early summer/Apr.1st〜Jun.30th.2008
Jul.1st〜Sep.27th.2008
Autumn〜Early Winter/Sep.28th〜Dec.16th.2008
Dec.17th.2008〜Mar.31st.2009
Spring〜Early summer/Apr.1st〜Jun.30th.2009
Jul.1st〜Sep.26th.2009
Autumn〜Early Winter/Sep.27th〜Dec.16th.2009
Dec.17th.2009〜Mar.31st.2010
Spring〜Early summer/Apr.1st〜Jun.30th.2010
Jul.1st〜Sep.11th.2010
Autumn〜Early Winter/Sep.12th〜Dec.17th.2010
Dec.18th.2010〜Mar.31st.2011
Spring〜Early summer/Apr.1st〜Jun.30th.2011
Jul.1st〜Sep.10th.2011
Autumn〜Early Winter/Sep.11th〜Dec.16th.2011
Dec.17th.2011〜Mar.31st.2012
Spring〜Early summer/Apr.1st〜Jun.30th.2012
Jul.1st〜Sep.21th.2012
Autumn〜Early Winter/Sep.22th〜Dec.16th.2012
Dec.17th.2012〜Mar.31st.2013
Spring〜Early summer/Apr.1st〜Jun.30th.2013
Jul.1st〜Sep.28th.2013
Autumn〜Early Winter/Sep.29th〜Dec.17th.2013
Dec.18th.2013〜Mar.31st.2014
Spring〜Early summer/Apr.1st〜Jun.30th.2014
Jul.1st〜Sep.28th.2014
Autumn〜Early Winter/Sep.29th〜Dec.16th.2014
Dec.17th.2014〜Mar.31st.2015
Spring〜Early summer/Apr.1st〜Jun.30th.2015
Jul.1st〜Sep.19th.2015
Autumn〜Early Winter/Sep.20th〜Dec.16th.2015
Dec.17th.2015〜Mar.31st.2016
Spring〜Early summer/Apr.1st〜Jun.30th.2016
Jul.1st〜Sep.19th.2016
Autumn〜Early Winter/Sep.20th〜Dec.16th.2016
Dec.17th.2016〜Mar.31st.2017
Spring〜Early summer/Apr.1st〜Jun.30th.2017
Jul.1st〜Sep.18th.2017
Autumn〜Early Winter/Sep.19th〜Dec.20th.2017

interval

Dec.21st.2017〜Mar.31st.2018

80

84
100
48
93
67

23rd stage

Spring〜Early summer/Apr.1st〜Jun.30th.2017

180

107

73

5,212

4,812

400

interval
Odor control
at Shin-Horikawa
River
At upstream of
Kinjo Bridge

reports

21st stage

interval

121

8Number of Reports
5500
5000
4500

5，212 reports
at the end of 23rd stage

4000
3000
Average of 200
reportsin every stage

2500
2000
1500
1000
500
0

Over 50,000 people joined in Chosatai.
Number of reports is above 5,000 in total.
第1st.
第2st.
第3st.
第4st.
第5st.
第6st.
第7st.
第8st.
第9st.
第10st.
第11st.
第12st.
第13st.
第14st.
第15st.
第16st.
第17st.
第18st.
第19st.
第20st.
第21st.
第22st.
第23st.

report3500

stage
We got 5,212 reports in total by when 23rd stage finished.
The number of reports by Shin-Horikawa River were 400 out of 5,212.
Lots of people research the water environment of Horikawa River
continually from a viewpoint and sense of citizens.

94. State of the weather
The weather changed with a cycle of several days in the 23rd
Stage(April-June). And, Highest temperature and maximum rainful
were recorded as a Stage from spring to early summer. In addition,
the time of entering rainy season was 6th June as average as normal.

Feature : Changes in climate with a cycle of several days
Recorded highest temperature and maximum rainful■Temperature
Average annual temperature was higher than normal value(18.7℃), andthe highest 19.9℃ since HSC started action. Average monthly temperature
is higher than normal value too, especially in April it was 2℃ higher.
■Precipitation
Average monthly rainfall is greater than normal value (160.8mm), and thegreatest 220mm since HSC started action. The monthly rainfall amount was
higher than normal value in April and May, and it was about normal value in
June.
■Sunshine Hours
Average monthly sunshine hours were 207 which are about 26 longer thannormal value. Average in all months It is longer than normal value.

Normal value for April to June (1981 to 2010) Average is 18.7℃

名古屋地方気象台 平年値(月ごとの値)
気温
降水量
区分
(℃)
(mm)
合計
平均
最高
統計期間
資料年数
4月
5月
6月

平均
9月
10月
11月
12月

平均

最低

日照時間
(時間)
合計

1981
〜2010

1981
〜2010

1981
〜2010

1981
〜2010

1981
〜2010

30
124.8
156.5
201.0
160.8
234.4
128.3
79.7
45.0
121.9

30
14.4
18.9
22.7
18.7
24.1
18.1
12.2
7.0
15.4

30
19.9
24.1
27.2
23.7
28.6
22.8
17.0
11.6
20.0

30
9.6
14.5
19.0
14.4
20.7
14.1
8.1
3.1
11.5

30
196.6
197.5
149.9
181.3
151.0
169.0
162.7
172.2
163.7

April

May

June

Changes of monthly averagetemperature （spring - early summer）

30
23.1

22.4

23.3 23.9 23.8

22.3

23.6 24.0

15
10
5

22.3

22.9 22.4 23.4
19.8

20
19.0 19.6 19.9 18.7 19.0 19.2 19.4 19.5
14.0 15.3 15.4 13.3

13.3 14.2 13.8

21.3 20.6 20.5

14.6 15.2

15.9 14.7 16.5

Average monthly temperature of 23rd stage is higher than normal
value for every month, in particular April is more than 2℃ higher
than normal value.
23rd Stage

21st Stage

19th Stage

17th Stage

15th Stage

13th Stage

11th Stage

9th Stage

7th Stage

5th Stage

0
3rd Stage

Temperature(℃)

25

1st Stage

23rd Stage

21st Stage

19th Stage

17th Stage

15th Stage

13th Stage

11th Stage

9th Stage

7th Stage

5th Stage

3rd Stage

22 Average temperature of 23rd stage was 19.9 ℃,
21 which was higher than normal value (18.7 ℃).
19.9
19.8
19.5
19.4 19.6
20
19.2
19.1
18.9
18.7
18.6 18.7 18.6
19
18
17
16
Average 18.7℃
15
14
13
0
12

1st Stage

Temperature(℃)

Changes of monthly average temperature（spring - early summer）

Source: Meteorological Agency ̲ Meteorological Statistics
Information Nagoya Local Meteorological Observatory
http://www.jma.go.jp/jma/menu/report.html

10

23rd stage Precipitation and temperature(ave.)
The beginning of rain season is June 6th )Weather condition in April and May had changed every few days.
Sunny day covered by high air pressure rose above 30℃. On
the other hand, there were heavy rain days because of low airpressure.
In June we had many sunny days because of high air pressure.
The beginning of rainy season is June 6th .

Record-breaking High temperature and frequent rain.

11

■ Shaping of Rapids and Pool
kingfishers, egrets, tortoises, etc.
fishes such as
carps, gibels,
hemibarbus barbus

small fishes suchas pale chubs, fries of palechubs etc.
rhinogobius

shrimps, crabs, aquatic insects, etc.

stacks ofstones

It was identified that variousorganisms breed and growwhen rapids and pools wereshaped.
Johoku Lions Club made adonation of building rapids andpools at Shinhori Bridge in thespring of 2018.
This place has been a habitatof organisms that like cobble
stones.

*denizen

Waterside
kingfishers,
egrets, etc.

■ Rise of self-purification by food chain
dirt of water (organic substance, nitrogen, phosphorus)

Prawns and Japanesemitten crabs areorganisms that
migrate between
rivers and the sea.

Algaes and microbes stick on stones with the dirt as nutrition.
Small fishes, shrimps, aquatic insects feed the algaes andthe microbes.
Big fishes and birds prey the small fishes and aquatic insects.
pale chubWatermauremys
reevesii,
trachemys
scripta*

carps, hemibarbus barbus
catfishes, black basses*,
bluegills*, northern snakeheads*

gibels, pale chubs, goby minnows,
rhinogobius, mosquitofishes*, etc.

palaemon paucidens, prawns,
Japanese mitten crabs, aquatic insects, etc.

These rapids and pools shaped at Shinhori Bridgein the spring of 2018.
Johoku Lions Club made the donation.
Rapids and pools shaped in thepast keep a diversity withchange according toenvironment.

Kurokawa No.1 Bridge

Pale chubs were eating
algaes on stones.

photo by the secretariat August in 201812

Newly sand-cover construction Securement of a water source Measures against smells
Bet. Sakura Bridge-Naka Bridge(Using shallow ground water)
at Shin-Horikawa River
Bet. Gojo Bridge-Habashita Bridge
Dec 2017-Jan 2018

A well at upstream of Kinjyo Bridge

started its operation in Mar 2018

(Dredging・Sand covering)
Downstream Dec 2017-Jun 2018
Upstream
Sep 2018-

Keiun Bridge

Gojo Bridge
Koshio Bridge

Habashita Bridge
School of young mullets
at the sand-covered place

Photos : May 15, 2018

Photos by the secretariat
Oct 7, 2018

Photos by the secretariat
May 17, 201813

5. 23rd stage survey report
Introduction 〜Column〜〜Column〜 For the clarification and regeneration of Horikawa River
Horikawa Sen-nin Chosatai (HSC)was established on 22nd April, 2007, as a place for citizens activities,
such as Fixed Point Observation Group, Free Survey Group and Cheering group, for clarification andregeneration of Horikawa River.
Fixed Point Observation Group examines Horikawa River to confirm the clarification effect by the measures
for water quality improvement and to make clear condition of water quality and cause of pollution, from aviewpoint and a sense of citizen. Free Survey Group studies Horikawa River from various view points.
Cheering Group supports clarification and regeneration of Horikawa River in various-free ways. These threegroups wish for clarification and regeneration of Horikawa River, and work together in a large network.
Currently(as of Sep. 29th 2018), there are 2,737 groups and 53,507 people in HSC. (101 groups in
Fixed Point Observation Groups, 40 groups in Free Survey Group and 2,596 groups in Cheering Group)
At the time of launch of HSC, there were 165 groups and 2,262 people. It shows that the network of
citizens wishing for clarification and regeneration of Horikawa River has expended greatly (conference2 :
pp6.7)
Fixed Point Observation Group observed 5,212 times from 1st stage to 23rd stage. So far, we found everchanging state of the water due to the influence of the tides, at the downstream from the Sanage Bridge.
And we found that a lot of observation results from the Fixed Point Observation Group can capture theaverage state of water quality of Horikawa River from citizens point of view and sense, and understand thetendency of the change of water quality. (conference3 : pp8.9)

14

5. 23rd stage survey report
Introduction 〜Column〜〜Column〜 For the clarification and regeneration of Horikawa River〜Pilot project of the clarification of Horikawa River〜;
we confirmed the clarification effect of TRWKR from April.2007 to March.2012
We confirmed that water quality between Sanage Bridge and Matsushige Bridge had been improved by
TRWKR(0.4m3/sec.) in this five years. And in this period, we confirmed that garbage (artificial garbage:
plastic type garbage etc.)were reduced. It is considered that because the citizen s awareness changed,
and cleaning activity became active.
【Five years summary】■We confirmed clarification effect of TRWKR.
■Network of citizens wishing for clarification and regeneration of Horikawa River has expanded greatly.
■Citizen s awareness changed, and the cleaning activity became active.

15

読売新聞 平成30年8月21日(1) Weather Condition
In the 23rd stage (from Apr. to June. 2018) the weather changed
every few days and the highest temperature and the heaviest rainfall
in the stage from Spring to early Summer was recorded. The rainyseason has started on June 6th, it was as early as an average year.
（Feature of the Weather in the 23rd stage) Change of theweather every few days, record breaking
temperature(highest) and rainfall(heaviest)(2) New Measures for Water Quality Improvement
After the stop of TRWKR in March 2010, new measures for water
quality improvement of Horikawa River have been implemented.
Shallow and deep in upstream section of Sanage Bridge for
improvement of self-purification function has been implemented
since FY 2012 and it continues thanks to the donation from Johoku
Lions Club in 2018.
Advanced water treatment at Meijo Water Treatment Center was
introduced and Horikawa Ugan Rain-water Reservoir for pollution
control was In-service in FY2010. Water conduction to Horikawa
River (max. 4,000 m³/day, during irrigation season(Apr.-Oct)using
recycled waste water (advanced treatment; membrane filtration
method)of Moriyama Water Treatment Center) started since FY2011.
Experiment of covering sand for water purification between the Naka
Bridge and the Gojo Bridge started in Feb. 2015. and by referingthat result construction of covering sand for improvement of water
environment between Habashita Bridge and Gojo Bridge andbetween Naka Bridge and Sakura Bridge was started in Dec. 2017.
The 8th well was dug in the upstream section of Kinjo Bridge in Mar.
2018 and utilization of shallow ground water (0.01m3) started as
new water source (Utilization of shallow ground water has been
implemented in 2004).

In Dec. 2017 dredging work and cover sand weremade as countermeasures against bad smell in thedown stream area of Shin-Horikawa, wheresedimentation and exposure of sludge, bubble andclouded water were found when citizens survey(general survey of Spring tide on Apr. 28. 2017.).
Dredging work has been also made in the upstream
area of Shin-Horikawa as a countermeasure against
bad smell since Sep. 2018.

16

(3) Change of the water quality of Horikawa River
The impression of the clearness of Horikawa River worsened after
stopping water conduction from the Kiso River. But, though, water
quality sometimes deteriorated due to weather conditions, etc.. ,generally there is a tendency of improvement little by little fromupstream. We think this is an effect of implementing new measures toimprove water quality after stopping water conduction. Especially for"smell", the proportion of tiger and sludge decreased, the proportionof odorless It tends to increase, and water quality and river bottom
condition are improving trends.
As a result of organizing the impression of clearness by section,
23rd stage was improved between Sanage Bridge and Asahi Bridge,
between Matsushige Bridge and Oseko Bridge. But between Asahi
Bridge and Matsushige Bridge got worse. In this section, Garbage"and Bubble from the bottom of the river increased, A situation was
different from other sections.
This Bubble from the bottom of the river is mainly accumulated insludge deposited on the bottom of the river between Asahi Bridge
and Matsushige Bridge, the increase in water temperatureaccompanying the rise in the recordable temperature.
Regarding Garbage", it increased due to rain that fell in the cycleof several days, stayed at the water's edge "Garbage" repeatedly
flowed out, accumulated and moved, stayed between Asahi Bridge
and Matsushige Bridge.
In the future, in addition to implementing measure so far, in order toimprove the water quality of the middle part of Horikawa River, we
hope that it will be discussed to the implementation of Sludge
Removal (continued) deposited on the bottom of the river, Regular
Ship s Sailing help reduce sludge?(Research / study), Effective
Removal of Floating Matter (research / inspection), in adittion to theflood control project.

Example of occurrence mechanismof Bubble from the bottom of the river
Odorless
The smell of eggs rotten
Water
Water
containing
sulfateion(SO42-)

BubbleSludgeWhen the water level goes
down, the water pressure on
the river bottom decreases,
and the bubble in sludge
become easy to release.

Increase Bubble

Sulfide(H2S, HS-, etc.)
Sulfate-reducing bacteria(mainly in the bottom mud)*Fungi that prefer theenvironment without oxygen

BubbleActivity of fungus
becomes active
as waterTemperature
increases

MethaneMethane-producing bacteria(mainly in the bottom mud)*Fungi that prefer theenvironment without oxygen

Accumulation and migration of Suspended Solids（Proposal） ★Sludge Removal (continued)★Regular Ship s Sailing help reduce sludge?(Research / study)(Source) The 22nd Survey Meeting Conference Report★Effective Removal of Floating Matter

17

Impression of
Water Clearness
The ratio of Clean 〜
Ordinary

Occurrence of
bubbles fromriver bottom
The ratio of bubbles
floating from the bottomof the river

Spring〜Early Summer(Apr.〜Jun.)：Odd number stage
Autumn〜Early Winter(Sep.〜Dec.):Even number stage18

（reference）

Occurrence of Smell
The average ratio of
Terrible Smell〜Smell

Spring〜Early Summer（Apr.〜Jun.）：Odd number stage
Autumn〜Early Winter（Sep.〜Dec.）：
Even number stage

Between Sanage Brdg. - Oseko Brdg.

Ditch

100

The ratio of smell type(％)

The ratio ofDitch Sludge
Smell less1st.
No data

30

63

62
57

60

40

56

55

57

52

41

44

38

31
36

26

33
30

37

38

21
6

33

31
21

18
10

19

19

19

22

15
21

16
12

13

37
32

24

22

25

23
18

43

40

32

32

24

43

38

48

50

35

36
20

9

44
35

29
22

22

26
12
12

19

22

11

10 18
5

59

58

57
49

44
35

65
61

55

19

0

74

63

59

48

20
10

Smell less

68

70

50

Ditch & Sludge

Reduction of Ditch and Sludge
Increase of Smell less
⇒Improve73

90
80

Sludge

15
10
6

8

7

1st. 2st. 3st. 4st. 5st. 6st. 7st. 8st. 9st. 10st. 11st. 12st. 13st. 14st. 15st. 16st. 17st. 18st. 19st. 20st. 21st. 22st. 23st.

19

Impression of Clearness

100

With TRWKR

40Worsend

21 After TRWKR
5
0

28

24

24

Down

27

17

12

5

H19.4.22 H20.4.1 H21.4.1 H22.4.1 H23.4.1 H24.4.1 H25.4.1 H26.4.1 H27.4.1 H28.4.1 H29.4.1 H30.4.1〜6.30 〜6.30 〜6.30 〜6.30 〜6.30 〜6.30 〜6.30 〜6.30 〜6.30 〜6.30 〜6.30 〜6.30
1st

3rd

5th

7th

60

11th

13th

15th

17th

19th

With TRWKR

53

61

60

Up

(参照：p.47)
Asahi Brdg.〜Matsusige
Brdg.

65
52

60

57

60

65

21st

62

67

74

20
H19.4.22 H20.4.1〜
〜6.30
6.30
1st

20
18
16
14
12
10
8
6
4
2
0

3rd

H21.4.1〜6.30

H22.4.1〜6.30

H23.4.1〜6.30

H24.4.1〜6.30

H25.4.1〜6.30

H26.4.1〜6.30

H27.4.1〜6.30

H28.4.1〜6.30

H29.4.1〜6.30

H30.4.1
〜6.30

5th

7th

9th

11th

13th

15th

17th

19th

21st

23rd

With TRWKR

15

14

13

②Smell

13

12

13

100%

④Garbage⑤Bubble⑥Creature⑦OtherGarbage

80
60

12

Up

With TRWKR
58

42

40

38

40

31
18

20
0

62

58

56

24

18

21

H19.4.22 H20.4.1 H21.4.1 H22.4.1 H23.4.1 H24.4.1 H25.4.1 H26.4.1 H27.4.1 H28.4.1 H29.4.1 H30.4.1〜6.30 〜6.30 〜6.30 〜6.30 〜6.30 〜6.30 〜6.30 〜6.30 〜6.30 〜6.30 〜6.30 〜6.30
1st

3rd

5th

7th

9th

11th

13th

15th

17th

19th

21st

23rd

Asahi Brdg.〜Matsusige
Smell Brdg

14
12

③Clearness

80%

1st Stage ： No Data
82 Data
21
5
13
18
19
11 3 37 Data1417
13
8 4 24 Data
22 Data514
23
43 Data
19
23
35 Data1123
932 Data
919
918
3 3 3 29 Data3
22 Data
18
5
14
7 3
21
3 29 Data29
5 5 21 Data
10

61
53
58
58
58
57
63
70
63
66
51

23rd

COD(参照：p.53)

Asahi
Brdg.〜Matsusige Brdg.
Asahi Brdg.〜Matsusige Brdg.
12

60%

100

40

0

①Color40%

Asahi Brdg.〜Matsusige Brdg

AsahiTransparency
Brdg.〜Matsusige Brdg.

100
80

9th

Qccurrence of Bubbles from river bottom (%)

0

11

Transparency(cm)

20

23

20%

1st Stage
3rd Stage
5th Stage
7th Stage
9th Stage
11th Stage
13th Stage
15th Stage
17th Stage
19th Stage
21st Stage
23rd Stage

Under 50％12

12

H19.4.22〜6.30

H20.4.1〜6.30

H21.4.1〜6.30

H22.4.1〜6.30

H23.4.1〜6.30

H24.4.1〜6.30

H25.4.1〜6.30

H26.4.1〜6.30

H27.4.1〜6.30

H28.4.1〜6.30

H29.4.1〜6.30

H30.4.1
〜6.30

1st

3rd

5th

7th

9th

11th

13th

15th

17th

19th

21st

23rd

Smell̲"Smell"〜"Terrible Smell"（％）

60

Asahi Brdg.〜Matsusige Brdg.

0%

Asahi Brdg.〜Matsusige Brdg.

80

COD(mg/L)

Impression of Clearness（％）

Impressionof Clearness
Asahi Brdg.〜Matsusige Brdg.

Asahi Brdg.〜Matsusige Brdg.
(参照：p.37)

Asahi Brdg.〜Matsusige Brdg.

100
80

With TRWKR

60
40

39

37

43

44

39
27

19

20
0

35

32

30

38

17

H19.4.22〜6.30

H20.4.1〜6.30

H21.4.1〜6.30

H22.4.1〜6.30

H23.4.1〜6.30

H24.4.1〜6.30

H25.4.1〜6.30

H26.4.1〜6.30

H27.4.1〜6.30

H28.4.1〜6.30

H29.4.1〜6.30

H30.4.1
〜6.30

1st

3rd

5th

7th

9th

11th

13th

15th

17th

19th

21st

23rd

20

■ Quality of water on rainy day
We sort out rainy day data from not rainy day data.*rainy day means it rained the day or the previous day.
As a result, we could confirm that the impression of water dirtiness is tend to improve even on rainy day. In
FY2017 the impression of water dirtiness is the same value between rainy day and not rainy day. Moreover,
Each evaluation method of the impression of water dirtiness(by color and bytransparency) leaded the sametendency that the percent of the impression of water dirtiness close the gap between rainy day and not rainyday. Therefore, by introducing new water quality treatment methods, water condition of rainy day is close tothat of not rainy day. To improve the Horikawa water quality, We expected a large effect of new water quality
treatment methods including Horikawa-sagan rain reservoir, advanced water treatment at Meijo water
treatment center and so on.

Hypothesis: The percent of the impression of water dirtiness close the gap
between rainy day and not rainy day ⇒ The water condition on rainy day improve.
With TRWKRNew Measures for Water Quality Improvement

Making shallows and deeps

Transmission of Raw Water from Shonai River
Use of shallow ground water
Introduction of advanced water treatment at Meijo Water Treatment Center

The percentage of water
dirtiness between “ordinary”
and “clean”

In-service of Horikawa Ugan Rain-water Reservoir for pollution control
Utilization of reclaimed wastewater at Moriyama Water Treatment Center

2015.4.1〜3.31

2016.4.1〜3.31

2017.4.1〜3.31

2010.4.1〜3.31

2014.4.1〜3.31

2009.4.1〜3.31

2013.4.1〜3.31

2008.4.1〜3.31

2012.4.1〜3.31

2007.4.22〜3.31

0

2011.4.1〜3.31

How has the impression of water dirtiness on rainy day changed?
The impression of water dirtiness on rainy day has improved little by little.(The percentage between ordinary
and clean increased).Especially in FY2017 the percent between ordinary and clean on rainy day is 40%
that is almost equal to that on not rainy day. We can see the effect of New measures for water quality
improvement even on rainy day.

2007

2008

2009

2010

2011

2012

2013

2014

2015

2016

2017

2007

2008

2009

2010

2011

not rainy days

557

403

280

2012

2013

2014

2015

2016

2017

236

272

304

261

279

269

214

rainy days

158

96

76

236

61

57

76

57

71

72

128

56

Fiscal year

The gap of impression of water dirtiness between rainy day and not rainy day(%)

By color

By transparency

How about the gap?
Not rainy day−rainy day

The gap is closing

2010 20112012 2013 2014 2015 2016 201721

■ Garbage and Suspended substance
Garbage and suspended substance have been decreasing while
repeating an increase and decrease, but they appear to increaseslightly in recent 21-23 stages. Garbage around Naya Bridge isincreasing recently. The cause might be thought that the more
offices prohibit smoking, the more people smoke and take a rest
drinking a can of coffee by the waterside.
These littering is a thoughtless behavior by a certain people
because cigarette butts and empty cans by the river are samebrand name products mostly.
The number of cleaning groups is increasing. However, garbage isthrown away as soon as cleaned up. We citizens have to think itover what we can do to resolve this problem.

Changes of garbage and suspended substance（Suggestions） ★Enhancing citizen s consciousness
・ Further expanding of cleanup activities （continue）★Appealing not to litter by the waterside

Photos by the secretariat

22

Opinions of secretariat for midstream of Horikawa River★The appeal of the prohibition of toss
the cigarette at the water edge area
★effective removal ofContinue with
Suspended substanceconfirmation of(research, investigation)
The removal based on the feature of thegather and movement or Suspended
substance

The time zone of ebb tide

Flow of Suspended
substance

Matsushige Lock Gate

The time zone of high tide

Continuation of Measures for
Water Quality Improvement(Opinions offered at
Summary meeting for the
18th stage)
In order to purify
Horikawa River■ Improvement of treated water・Advanced water treatment
at the Meijo Water Treatment CenterWe citizens can do many things.
■ Improvement of combined sewer
effect by citizens.
For example, the waste water
systemfrom our house into the sewage
・The Horikawa Ugan, Sagan
・Transparency was
becomes clearer, the water from
Rain-water Reservoir■ Securement of Additional Water
improved
the sewage into Horikawa River
also becomes clearer
・ＣＯＤ was improved Resource
・Utilization of Reclaimed Wastewater
What can we do to reduce the・Bubbles from the・Utilization of shallow ground water
dirt from our house?
bottom of the river was■ Improvement of the natural
purification capacity
reducedLet s reduce the dirt
・Ditch, Sludge smell was ・Creation of Sehuchi
from our house.
・Covered sandreduced★Removal of sludge(continuation) (1)Reduce the dirt from kitchen(2)Reduce the dirt from washing・Suspended substance
was reduced★Improvement of
citizen s consciousness（Source） Summary meeting forthe 21st stage p.92,93

Sanage Bridge

Matsushige
Oseko Bridge Bridge Asahi BridgeJohoku Bridge

・expansion of cleaning
activity(continuation)★Regular sailings of ships can reduce the sludge?
(research, investigation）

Impression of Water dirt was improved
Salt water
Bottom material was improved by
combined effect. We expect the recoveryof the natural purification capacity.

（Source） Summary meeting for the 22nd stage p.32

23

Impression of Clearness(4) Water Quality of Shin-Horikawa
River

Impression of Clearness(％)

Dirty

We got 400 reports of Shin Horikawa by
when 23th stage finished.
It became clear that the Impression of
Maizuru Bridge〜Mukaida Bridge is
especially bad.

Slightly Dirty

Ordinary

Slightly Clean

Clean

Under 50％(Bad)

Impression of Clearness（In Year）[1]Dirty

Impression of Clearness（％）

100%
90%

5
5

8

[2]Slightly Dirty
420

7[3]Ordinary
3
3

9
6

[4]Slightly Clean
3
7
16

11

[5]Clean448Uchida Ukishima Atsuta Hinode Tateishi Horagai Shinonome Mukoda Oi

38

70%

46

20

40

43

19

21

41

57

38
44

43

40%
30%

54

50

60

53

51

43

50
42

44

40

33

10%

19

18
8

0%
Apr.

May

Jun.

Jul.

Aug.

Sep.

Oct.

Nov.

14

Dec.

Jan.

Feb.

38

42

45

Mar.

Smell（In Year）
100%
90%

7
21

28
38

80%

20

Smell(%)

26

28

47
30
25

40%

36
20

29

22

10

8

Apr.

May

4
Jun.

0%

3

21
7
Jul.

28
29

13

27

28

16
33

12

10%

32

13

17

20%
10

30

41

26

50%

30%

22

36

70%
60%

Kinen

Uzura

Maizuru

12

50%

20%

Utsugi

32

80%

60%

4

13

11

8

23

18

19

3
Nov.

4
Dec.

4
Jan.

22

13

10

13

Aug.

Sep.

Oct.

10

12

28

14
3
Feb.

[5]No Smell[4]Slight Smell[3]Smell[2]Bad Smell[1]Terrible Smell

About impression of clearness, thepercentage of Dirty , Slight Dirty isover 50%. Ecpetialy, the percentage
of April〜Octobar and March is over80%.
About smell, the percentage ofTerrible Smell is high over the full
year. The percentage of Terrible
Smell and Bad Smell is high in
Septembar, Octobar and March.
There are still many things we don t
understand about Shin-Horikawa river,
so we need continuous survey in as
many spots as possible.

4
Mar.

24

Kids-Kankyou-Ecoword

Fixed Point Observation in Shin-Horikawa River（Data）
Fixed Point Observation ＥＣＯ-doco Ouen-Tai
at Mukaida Bridge
URL http://www.eco-doco.jp/meiko̲line/html/01.html
Number of survey data：105 （105 pictures）
Survey period：April 2, 2015 〜 June 30, 2018
Tide level at survey：T.P.-148cm〜98cm＊T.P. is the elevation from the average sea level in Tokyo Bay at
the Japanese level origin

The color of the water at the time of observation was chosen bycomparing the sample of color and the picture of the homepage. The
tide level at the fixed point observation was based on the hourly dataof the Japan Meteorological Agency.
⑬yellow
brown
⑥gray
⑫pale
⑦yellow
5%5%gray yellow
gray
10%
11%
⑪dark
gray
5%
All data of occurrence
frequency of water color
Average tide level
T.P.-17cm
⑧pale
n=105
⑩gray
gray yellow
green
green
28%
33%
⑨gray
yellow＊The water color of whitegrenn
cloudy(⑧pale gray yellow
3%green＋⑫pale gray yellow)■ The impression of the water color in Mukaida Bridge
The impression of the water color in Shin-Horikawa
river based on picture by Fixed Point Observation ＥＣＯ-doco Ouen-Tai were organized.
1)The water color of white cloudy(⑧pale gray yellow
green＋⑫pale gray yellow) in Shin-Horikawa Riveraccounts for 40% of all data. It often occurs at springtide and middle tide.
2) The water color of green and yellowish-brown often
occurs at neap tide and long tide, wakasio. Thisphenomenon may be caused by plankton.
Mukaida Bridge is near Horidome which is at the most
upstream. The color of the river water to change
according to plankton. It is different from the reportnear Horidome. It is a valuable report to understand thesituation of the Shin-Horikawa.
Change in color by plankton

25

(5)Simultaneous survey of neap tide

May 8th .2018

1） Change in tide level
・The tide level difference of the tide of Nagoya Port was about 0.9m.
・The tide level difference at the time of Simultaneous survey of spring tide conducted last year was 2.5m, andthe change in the tide level this neap tide were less than half of those at the time of spring tide.
2） Weather condition
・37.5mm of rain fell the day before the survey of neap tide. Also on the day of the survey it started fall rainfrom around 5 PM. As a result the survey was conducted in a state that received little influence of rain.
3） Direction of water flow and accumulation of suspended substance・There were few reports of upstream flow in the high tide time zone, and there was no report of the tide(accumulation of suspended substance) that went up to the vicinity of Gojo Bridge as in the case of springtide. In the neap tide section of Horikawa and Shin-Horikawa River where water source was limited, it seems
that at neap tide with little tidal change , the environmental became easier for water to stagnate than at thetime of the tide.

Change in tide level264） Hydration of sludge
・In the survey of spring tide
last year, hydration sludge
was reported between
Kameya Bridge andHabashita Bridge in the timezone close to ebb tide. On
the other hand, there is noreport on hydration of sludge
in the survey of neap tide.
5） Impression and evaluationof water clearness
・The Impression of water
clearness of Horikawa Riveris clean~slightly clean at
the time of neap tide than
the spring tide.
・Shin-Horikawa Rivergenerally has a bad
impression of water
clearness. Especially at thetime of neap tide theproportion of dirty
occupies about 60%, theImpression of water
clearness is even worse than
the spring tide.

Impression and evaluation of water clearness
Horikawa
River

Shin-Horikawa
River
About
60％

26％ The Impression Horikawa
of waterclearness of
Horikawa Riveris less clean~slightly clean
at the neap
tide than at
the high tide.
About 40%
was dirty
especially at
the spring tide.

0％

18％

River About40％

0％
Shin-Horikawa
Shin-Horikawa
River generally has Rivera bad impressionof water clearness.
Especially at thetime of neap tidethe proportion of
dirty occupies
about 60%, theImpression of water
clearness is evenworse than springtide.
※Not enough date27

(6) Migratory Creatures

ascending Horikawa River
Larval fish ascending to upstream were
witnessed this year, too. Menbers of Survey
Groups and Horikawa Cheering Groups took
pictures of them and of birds flying to prey onthem.
Moreover a crab crawling up the artificial
waterfall beside Sanage Bridge was witnessed
and we took pictures of it. This discovery shows
us that crabs born in the sea grow up in and run
up Horikawa River and that the number of themis increasing.
And we caught 3 eels of 20-30cm long. They
probably grew up in Horikawa River because
larval eels were witnessed near Nayabashi
Bridge before.
Mass dead fish caused by the deficiency ofoxygen did NOT happen in this 23rd stage eventhough high temperature and large rainfall
worsened the impression of water between Asahi
Bridge to Matsushige Bridge.
Although the status of Horikawa Riversometimes worsens by the weather temporarily,
it is getting better as the measures are taken.
We expect that Horikawa River gets into the newphase and is recovering its ecosystem.

Sanage Bridge
water fall

Larval fish

A crab crawling up
the water fall28

■ Observation record of covering riverbed with sandThree eels (length 20cm ~30 cm) were caught on theleft side of Sanage-Bridge's head fall downstream.
Photographed by: Survey group River Planning Division

Between Naka-Bridge and Gojo-Bridge, three years
and fourth spring have passed from covering riverbed
with sand . We can still confirm the purificationmaterial and sand granules. However, it seems thatsludge is tend to accumulate in the recessed area as
our findings.
We could find many groups of mullet and goby at theedge of water between Gojo-Bridge and HabashitaBridge.

Naka-Bridge

Date: July 17, 2018

Condition from three years
passed after coveringriverbed with sand .
Downstream of Gojo-Bridge
Young eel at Naya-Bridge(Around 10cm)
Date: May 28 2014

Cormorant

Photographed and reported by: Earth club survey group
Goryo-Bridge
Date: April 25 2018
We were able to encounter hundreds of cormorants
while we took the walk in the early morning.
We felt a surge of surprising and pleasure !
Photographed and reported by：Ogawa
Between Oseko-Bridge and Shiratori-Bridge
Date: May 5 2018

Date: June 14 2018
Kingfisher survey group

Condition from three years passed
after covering riverbed with sand .
Downstream of Gojo-Bridge right side

Date: May 16 2018
Uncovered area
Downstream of Sakura-Bridge
right sideAround Habashita‒Bridge
Group of mullet young fish

Around Habashita‒Bridge
Group of goby young fish

We could confirm a lot of mullet young fish between
pier and river bulkhead.
Mullet young fish stand out in particular this year.
Especially, this tendency is remarkable at Shiratori.
Photographed by: Nagoya Horikawa Lions Club survey
group
Shiratori harbor
Date: June 2 2018

Goby young fish

29

Observation of the Sand Cover

中橋

3 years have passed since riverbed was covered with thesand between Nakabashi Bridge to Gojo Bridge. It has
been clear that you can see the sand of riverbed.
However hollow places seem to get sludge gathering
easily. Lots of larval fish were witnessed in the shoal
between Gojo Bridge to Habashita Bridge.

3 years after sand cover
Gojo Bridge

小塩橋

Habashita Bridgea place without sand cover
Sakura Bridge

小塩橋

6 months after sand coverHabashita Bridge

3 years after sand cover
Gojo Brigdge
larval fish
Habashita Bridge

larval fish
Habashita Bridge

30

from secretariat■ Every data you offer to us is valuable
Information about subtle change you find when you survey Horikawa river can bevaluable data to understand the present situation of the river. We re looking forward
to your data from now on.
■ Let us introduce your activity
Your activity, such as survey, think and cheer up Horikawa, is the motivation toincrease the number of those who love Horikawa, Nagoya City and the Earth.
■ Let s hand down the past appearance of Horikawa as record
To know about the past Horikawa is very important to design the future Horikawa.
We refer Horikawa s pictyures taken in Taisho and Showa era to know forgotten
past Horikawa. Do you keep photos which Horikawa was photographed in in youralbum? For example, photo of your family with Horikawa in the background of thepicture is Okay.
(contact)secretariat
e-mail:2010@horikawa1000nin.jp
Please send comments and pictures (with date and place) from mobile phone orPC.
＊We think image quality of picture taken by mobile phone camera is enough.

31