4. Bubbles

Nishikibashi Bridge 2009.6.12
middle tide

Nishikbashii Bridge 2009.6.23, Spring tidephoto: Kawasemi survey group

Sanage Bridge
photo: Goyousuiatogaienaigokai survey group

Shiga Bridge
photo: shinkou survey group48

4.1. Generation status of bubbles( vertical direction ) 1st stage - 5th stage
530
3380%

50%

928640%→
Nagoya Port30%
20%10%→
Confluence of Shinhorikawa

60%

32

089
62065

70

As
ahiB
Br
rididggee～
Jy
Jyohohokokuu
BrBr
ididg
gee～
SaSananagegeBrBridg
idg
ee～
Sakae
BridgeAsahiM
atsu
shige

Br
idge～

Mate～
Bridg

koOsesushige

OsekoBridg

Bridg
ee0%

hi
Bridg
e～

192270%Min
atoshinbas1113→
Raw water transmission from Syounai river

14090%

830

Injection of TRWKR →General Status of Bubbles, Component Ration(%)

100%（with TRWKR;
No rain : previous day
and current day）
Bubbles come from the bottom ofriver
Bubbles float from upstream site
Bubbles float from downstream site
No bubbles■What kind of bubble ?
・Sakae Bridge – Jyouhoku Bridge area; Bubbles
float from upstream site. These bubbles result fromdrops.
・Asahi Bridge – Matsushige Bridge area; Bubbles
come from the bottom of river. These bubbles result
a mount of sludge at the bottom of river.
49

4.2. Generation status of bubbles (by district)（with TRWKR;, No rain : previous day and current day）
Sakae Bridge～Sanage Bridge

90%

1325

2480%
70%

8033
50

060%

130Bubbles come from the bottomof river
Bubbles float from upstream site

2050%

040%
30%

100%

367074

73
4720%

5010%

Bubbles float from downstreamsite
No bubbles

General Status of Bubbles, Conponent ratio(%)

General Status of Bubbles, Conponent ratio(%)

100%

Sanage Bridge～Koushin Bridge

1490%
80%

33

421631

22

17
7
170%
60%

91

12
050%
40%
30%

80
5955

Thefrequencyof bubbles
8075
occur
wasimproved.

Bubbles come from the bottomof river
Bubbles float from upstream site
Bubbles float from downstreamsite
No bubbles

20%
10%0%0%the 1ststage

the 2ndstagethe 3rdstage

the 4thstage

the 5thstage

the 1ststage

the 2ndstage

the 3rdstage

the 4thstage

the 5thstage■Difference of occurrence frequency of bubbles（Sanage Bridge-Kousin Bridge）
・Compared with the 1st stage, the occurrence frequency of bubbles at the 5th stage
decrease. （= change for the better）
・The 1st ,3rd and 5th stage (spring – early summer), frequency of bubbles occur were morethan the 2nd and 4th stage (fall – winter). The reason is that bubbles rise up from bottom of
HR increase（= cause of sludge）.
50

Generation status of bubbles( Sanage Bridge – Kousin bridge ; by district )

100%
80%
60%
40%
20%

21300690

190
1102408985
57

4911150740%
thethethethethe
1st
2nd 3rd
4th
5thstage stage stage stage stage

Asahi Bridge～Matsushige Bridge

Bubbles come fromthe bottom of river
Bubbles float fromupstream site
Bubbles float fromdownstream site
No bubbles

Conponent ratio(%)

Conponent ratio(%)

Sanage Brdge～Johoku Bridge

100%
80%
60%

5840%

2020%

4050

84

9520%

0100

92
500%
thethethethethe
1st
2nd 3rd
4th
5thstage stage stage stage stage

4230704255

Bubbles come fromthe bottom of river
Bubbles float fromupstream site
Bubbles float fromdownstream site
No bubbles

Matsushige Bridge～Oseko Bridge

805060%40%

01300

thethethethethe
1st
2nd 3rd
4th
5thstage stage stage stage stage

Bubbles come fromthe bottom of river
Bubbles float fromupstream site
Bubbles float fromdownstream site
No bubbles

Conponent ratio(%)

Conponent ratio(%)

80%

880

69560%

Johoku Bridge～Asahi Bridge
100%2344100%
80%

7070338694313060%
40%

840100047

8920%0%thethethethethe
1st
2nd 3rd
4th
5thstage stage stage stage stage

Bubbles come fromthe bottom of river
Bubbles float fromupstream site
Bubbles float fromdownstream site
No bubbles

51

Generation status of bubbles( Sanage Bridge – Kousin bridge ; by district )Conponent ratio(%)

Oseko Bridge～Minatoshinbashi Bridge
100%
80%
60%
40%

000033
0100

100

100

100

67

20%
0%
thethethethethe
5th
4th
1st
2nd 3rdstage stage stage stage stage

Bubbles come fromthe bottom of river
Bubbles float fromupstream site
Bubbles float fromdownstream site
No bubbles* Which area was the worst situation?
There are a lot of bubbles at Sakae bridge to Jyouhoku bridge area.（case of drops ：ex. Sanagebridge)
There are some bubbles from the bottom of river at Asahi bridge to Matsushige bridge area. We
think that the reason is sludge.
The 5th stage at Sanage bridge to Jyouhoku bridge area and Asahi bridge to Matsushige bridge area
is better than the 1st stage (shortly after starting raw water transmission)->occurrence frequency of bubbles decrease, change for the better, at Jyouhoku bridge toMatsushige bridge area and Asahi bridge to Mastushige bridge area.

Column - About bubbles We HSC explain some observed bubbles from 1st stage to 5th stage.
We organized our research results each area. （ref. 4.1.）
There were some bubbles from upstream site at Sakae bridge to Jyouhoku Bridgearea. We think the cause was drops ,as shown in example of Sanage bridge.
Furthermore, bubbles from the bottom of river at Asahi bridge to Matsushigebridge area were more than other area. We think the cause was a mount of sludge atthe bottom of river.
Next, We classified generation status of bubbles each stage. （ref. 4.2.）
These survey found that occurrence frequency of bubbles at the 5th stage
decreased compared with the 1st stage, occurrence frequency of bubbles in springand early summer is higher than in fall and early winter.

52

In addition, We classified generation status of bubbles each stage and area. (ref.
4.3.)
These survey found that occurrence frequency of bubbles at Sanage bridge toJyouhoku bridge, Aasahi bridge to Matsushige bridge of the 5th stage decreased
compare with the 1st stage.
Additional Notes
The amount of bubble thought to be causally related sludge is influenced byaccumulated sludge, water temperature, air temperature and sea tide etc.
*About the Influence of sea tide
(example) drawdown: Bubbles are produced by the release reduced water pressure.
increase the flow rate: Bubbles are produced by mixing a mount of sludge.