Climate Change Impacts
to the Water Environment
February 23rd , 2011
WEPA 2nd International Workshop

Takatoshi Wako
Deputy Director, Water Environment Division
Environment Management Bureau, Ministry of the Environment, Japan

Today’s Topic• Does climate change really affect on waterenvironment? How seriously?
• Tentative report from “Investigative Commission
for Impact on Water Environment by Climate Change”◆

Past Data Analysis◆

Detailed Analysis: Ikeda Lake◆

◆Forecasting Water Quality in the future with ClimateChange
Possible Adaptation Measure

Ministry of the Environment

2Most of threads emerge in the form of “Water”

Ministry of the Environment

Source: Japan Water Forum(http://www.waterforum.jp/eng/)

Not only “Water quantity”, but also “Water Quality”• Example of the Impact on Water Environmentin Japan
Delay of Water
Circulation In Lake Biwa.

Water circulation has
stooped in Lake Ikeda
since 1986. From 1990,
Anoxic layer is at under
200 meters deep.

Low Dissolved Oxygen
level in Tokyo bay.
Water temperatures in Kiso River
raised by maximum 2 degree in
1994,it caused flow reduction anddeclining water quality

Ministry of the Environment

Tropical fish in TamaRiver, Tokyo

Possible Impact of climate change on Water Quality

Previously‐Observed• Increase in Annual mean water temperature• Abnormal growth of Algae in Lakes• Expansion of Red tide damage by Drought

In the future• Declining Water Quality in the River by Heavy Rain and Drought• Water Temperature Rise in River, Lake and Groundwater• Increase in Amount of Evaportranspiration• Change of Snowmelt runoff• Stop of the Water Circulation in Lake
• Increase in Abnormal Growth of Algae• Change in Water Use and Aquatic Ecosystem
Ministry of the Environment

Possible Impact of climate change on Aquatic Ecosystem

Previously‐Observed• Change of Ecosystem by stopping of Water Circulation anddecrease of Dissolved Oxygen• Habitat Change of Cold‐water fish in fresh water• Increase in Southern Strain and Decrease in Northern Strain in
Coastal area
• Coral death and bleaching

In the future• Change of Habitat Range in fresh water• Invasion of Alien Species• Impact on Plankton by acidification in the sea• Expand of Coral bleaching• Decrease in Sandy Shore
Ministry of the Environment

Investigative Commissionfor Impact on Water Environment by Climate Change• Established in 2010 ( 4 years project)

Goals:• To clarify the Impact on Water Environment in public water bodyby Climate Change and to investigate the Adaptation measures.

What we have done so far:• To get clear understanding about the items (Water Quality,Water Temperature ,etc.) effected by Climate Change• To decide the basic concept about the Forecasting Method• To decide the plan of future investigation and schedule
Ministry of the Environment

Past Data Analysis‐ Relation between air temperature and water temperature ‐All Water quality analysis points on nationwide(in 2007)8,756 (6,053 in River, 529 in Lake, 2,174 in Sea )Extracted only points with long-term (27 years record)

Points under Analysis
Calculate the average Water temperature in Summer season and Winter4,477 (3,121 in River, 265 in Lake, 1,091 in Sea )Extract points showing clear increase trend in water temperature
Criteria1) Significant difference btwn ‘80’s and ‘00’s by Mann-Whitney U test2) Slope of regression line is positive
3) Average temperature of each decade (T’80T’90T’00) shows

Points show the clear increase in Water temperature1,405 [31.4%] (997 [31.9%] in River, 68 [25.7%] in Lake, 340 [31.2%] in Sea)
※Points showing clear decrease in Water temperature in only 3%, by reverse criteria

Ministry of the Environment

Past Data Analysis
Water temperature increase on Population Density

Population Density

Water
Temperature Temperature Increase (℃)
Summer WinterIncrease both Sum & Win
No Increase

Ministry of the Environment

Past Data Analysis
Water temperature increase (Kansai and Chubu region in detail)Ministry of the Environment

Correlativity bwn Air Temp. & Water Temp. (Rivers)
N=3,121
Water Temperature change for 30 years （℃）

Summer
5.00.0

-5.0
0.0

1.0

2.0

Air Temperature change for 30 years （℃）

3.0

Water Temperature change for 30 years （℃）

10.0

10.0

Winter
5.0

0.0

-5.0
0.0

1.0

2.0

Air Temperature change for 30 years （℃）• Change in water temperature is larger than those in air,especially in winter• Winter data is slightly correlated, but not explicitly
Ministry of the Environment3.0

Human Activity Impact on Water Temperature (Rivers)
6.0

Winter

6.0

4.04.02.0

2.0

0.0

0.0

110100

1000

10000

100000-2.0

8.0101001000

10000

100000-4.0

Population Density (person/km2)

Population Density (person/km2)

Summer

6.0
4.0
2.0
0.0
0.0%

1-2.0-4.0

Water Temperature change （℃）

Water Temperature change for 30 years（℃）

Summer

8.0

0.1%

1.0%

10.0%

-2.0-4.0

Ministry of the Environment
Ratio of Urbanized Area

100.0%

8.0

Water Temperature change （℃）

Water Temperature change for 30 years
（℃）

8.0

Winter
6.0
4.0
2.0
0.0
0.0%

0.1%

1.0%10.0%

-2.0
-4.0

Ratio of Urbanized Area

100.0%

4.0

WinterSummer

夏季気温×夏季水温
厚岸湖

3.0

1:1 ライン釜房ダム

一定の相関性がある
野尻湖

2.0
十和田湖

屈斜路湖
琵琶湖南湖
琵琶湖北湖

印旛沼

手賀沼

八郎湖

1.0

霞ヶ浦

佐鳴湖
池田湖

0.0

中海

田沢湖

0.0
-1.0

河口湖

猪苗代湖

小川原湖諏訪湖
浜名湖
宍道湖

1.0

洞爺湖

サロマ湖

2.0

児島湖

阿寒湖

-2.0

夏季30年間気温変化（℃）
Air temperaturechange for 30 years (℃)

3.0

Water temperaturechange for 30 years (℃)
冬季30年間水温変化（℃）

夏季30年間水温変化（℃）
Water temperaturechange for 30 years (℃)

Correlativity bwn Air Temp. & Water Temp. (Lakes in Japan)
冬季気温×冬季水温3.0

1:1 ライン
野尻湖

2.0

浜名湖
宍道湖
池田湖

1.0

琵琶湖北湖
釜房ダム

諏訪湖

琵琶湖南湖

河口湖

0.0

0.5

1.0

1.5

2.0

-1.0

2.5
児島湖

※冬季欠測湖沼

八郎湖

佐鳴湖

田沢湖
中禅寺湖
サロマ湖
十和田湖
屈斜路湖
厚岸湖
洞爺湖
阿寒湖 猪苗代湖

Air temperaturechange for 30 years (℃)
冬季30年間気温変化（℃）• Summer data is slightly correlated, but not explicitly

Ministry of the Environment

印旛沼

小川原湖

0.0

-2.0

中海手賀沼
霞ヶ浦

Detailed Analysis: Ikeda Lake (Kagoshima)

Outline of Ikeda Lake• Located in southern part of Japan• Diameter: 3.5km, Circuit: 15km,
Water Depth: 233m
• Once known as a very transparent lake,domestic and industrial waste water
deteriorated water quality in early 1980’s.
• Due to rise of average water temperature in winter, vertical circulationof lake water had stopped in late ‘80s. That has degraded DO level atthe bottom

Ministry of the Environment

Detailed Analysis: Ikeda Lake (Kagoshima)

Air temp.(degreeCelsius)

19.5
Air temp. (Makura-zaki, annual ave.)

19.0
18.5
18.0
17.5
17.0'80'850mWater temp.
(degree Celsius)

35

'90
15m

'95
30m

'00

'05

100m

'10200m

Water temp.

30
25
20
15
10
5'80

Ministry of the Environment

'85

'90

'95

'00

'05

'10

Detailed Analysis: Ikeda Lake (Kagoshima)
Air temp.(degreeCelsius)

19.5
Air temp. (Makura-zaki, annual ave.)

19.0
18.5
18.0
17.5
17.0
5'80
6 '80

'85
'85

COD

'90
'90
0m

'95
'95
15m

'00
'00
30m

'05
'05

'10
'10
100m

200m

COD（mg/L）

54
3
2
1012 '80

'85

'90

'95

'00

'05

'10'85

'90

'95

'00

'05

'10DODO（mg/L）

1086420'80

Ministry of the Environment

Complex mechanism of Climate Change Impacts
to the Water Environment

Ministry of the Environment17Forecasting Water Quality in the future with Climate Change• Field: Lake Biwa (from this year)

Input Data

Delivery Data

•River•River（Discharge, Water
Quality, Flow velocity)•Groundwater(Level, Quality)•Evapotranspiration•Volume of accumulated
and melting snow etc•Climate（Rainfall,Temperature, Insolation,
Wind Direction & Speed•Outflow Dischargeetc•Climate（Insolation)
etc

Ministry of the Environment

Output Data

Land area water & material
circulation model
Inflow Discharge from rivers

Pollution loads from rivers

Discharge from lake bed

Pollution loads from lake bed

Lake water
Flux model（COD, TN, TP, TOC ,Dissolved & Suspendedmaterials）（Discharge, Water
Quality, Flow velocity)•Groundwater(Level, Quality)•Evapotranspiration•Volume of accumulated
and melting snow etc
Flow Direction and Speed
Water Temperature
Distribution
Water Level

Flow Direction and Speed
Water Temperature
Distribution

Aquatic Ecosystem model

Water Quality Distribution(COD, TN, TP etc.)

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Possible Adaptation Measureon changes in Water Environment by Climate Change
Adaptation based on Technology (Water quality management)• Applicable only to small rivers and lakes

Adaptation based on Policy(Regulation on heated effluent, Add‐on effluent standards)• Applicable only to small rivers and lakes• Preparing measures to prevent invasion of tropical alien plant

Adaptation with no action• Let it be• Adaptation with conformist action along with what happens

Adaptation with no action• Learn from tropical countries experience and countermeasure
Ministry of the Environment

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Thank you for your attention
Contact: WAKO_TAKATOSHI@env.go.jp

Ministry of the Environment

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