Comprehensive Urban RiverBasin Management in Japan

Regional Workshop on Climate Change and Urban Flood Management

March 19-20, 2013Daegu, Republic of Korea

1

Masahiro IMBE

Association for Rainwater Storage & Infiltration Technology

ARSIT

Today’s Presentation

2

ARSIT

1. Direction of Comprehensive Urban River Basin Management in Japan

2. Comprehensive Mitigation Measures against Flood Damage

3. New Act for Urban Inundation Prevention

4. Progressive Urban Water Management

5. Master & Action Plan for Sound Water Cycle

6. Conclusive Comments

3

ARSIT

Comprehensive Mitigation Measuresagainst Flood Damage

proposed by the River Council

Legislation of New Act for

Urban Inundation Prevention

Preservation of Well-balancedWater Cycle

Proposed by the River Council

Rainwater Storage and

Infiltration Facilities

(Flood Control) (Well-balanced Hydrological System)

in 1977

in 2003

in 1996

Future Direction

1．Direction of Comprehensive Urban River Basin Management in Japan

Well-balanced condition offlood control,effective rainwater utilization &aqua-environmental improvement

Stormwater Treatment Allotments（Description using Hydrograph）

Basin-wide

Storage

Facility

Basin-wide Design Flood Discharge

TimeT

Hydrograph forRiver Planning

Hydrograph for Sewerage Planning

⑤Channel Allotment（Discharge Facility）＜Including DischargeFrom Main Storm Sewer＞

②Basin-wide Allotment（Artificial Water Retentionand Retarding Function）

④Retarding Pond Allotment（Storage Facility）

③Sewerage Allotment（Storage Facility）

River Flow Discharge, Q

Basic Design Flood Discharge

Design Flood Discharge

4

ARSIT

2．Comprehensive Mitigation Measures against Flood Damage

Conservation of Urbanization Control Area

Variety of Comprehensive Mitigation Measuresaccording to Stormwater Treatment Allotments in Basin

①Natural Control Function

②Basin-wide Allotment

③ＳｅｗａｒａｇｅＡｌｌｏｔｍｅｎｔ

④Regulating Pond Allotment

⑤ＣｈａｎｎｅｌＡｌｌｏｔｍｅｎｔ

Storage Facility

Permeable Pavement

Permeable Box

Floor Elevated Building

Storage Facility

Sewarage Storage

Anti-disaster Reservoir

Play-lot Storage

Retarding Basin Infiltration Facility

Improvement of River Channel

Sewarage Facility

Conservation of Green Land

5

Riv

ersi

de

flo

od

co

ntr

ol

mea

sure

s

La

nd

sid

e in

un

da

tio

n c

on

trol

mea

sure

s

Structural measures Nonstructural measuresRiver Law

Sewerage Law Town Planning Law

Flood Prevention Law

Stormwater retention and infiltrationfacilities in the river basin

Requiring the provision of drainage facilities with retention and infiltration functions (by ordinances)

Wastewater drainage and disposal Permission for development

Flood control measures includingriver channels and dams Designation of inundation hazard areas

(post-flood measures)(pre-flood measures)

New actDesignation of urban river and urban river basin (ministers, prefectural governors)

•

• Designation of urban flood hazard area and urban inundation hazard area for riverside flood and landside inundation

•

•

Requiring the provision of retention and infiltration facilities associated with acts that hamper storm-water infiltration

Advice on the obligation to notify of the filling-in of existing stormwater reservoirs and measures to be taken

Conclusion of management agreement bylocal government

Drawing up of "river basin inundation prevention plan" for comprehensive inundation prevention measures (river administrator, sewerage administrator, prefectural governor, municipal head)

(river administrator)

6

ARSIT

3. New Act for Urban Inundation Prevention

ConventionalInlet Reduction of Runoff Discharge

by adding the Infiltration Functionto Conventional Inlet

② Retention and infiltration function can be added to drainagefacilities of each house in accordance with the ordinance.

7

ARSIT

3. New Act for Urban Inundation Prevention

After Development without Measures

After Implementation

Time

Time

Ru

nof

f D

isch

arge

(Q

)R

un

off

Dis

cha

rge

(Q)

Runoff after DevelopmentRunoff before Development

Increasedue to Development

Measures by Storm WaterRetention and Infiltration

Runoff Dischargeafter Implementation

Reduction tothe Max. Runoffbefore Development

③ It regulates the actsthat hamper functionsof storm water retention and infiltration

8

ARSIT

3. New Act for Urban Inundation Prevention

Existing storm water detention pond (approximately 500 m3 scale)

Overview after landfill

④Prefectural governor can designate a large storm water retention pond as the specified pond to be preserved.

9

ARSIT

3. New Act for Urban Inundation Prevention

10

Urban Water Management Transitions Framework

R. Brown, N. Keath and T. Wong, (2008) Transitioning to Water Sensitive Cities: Historical, Current and Future Transition States, 11th International Conference on Urban Drainage, Edinburgh, Scotland, UK

(Reference)

Water SupplyCity

SeweredCity

DrainedCity

WaterwaysCity

Water CycleCity

Water SensitiveCity

Supplyhydraulics

Separatesewerageschemes

Drainage,channelisation

Point &diffuse sourcepollutionmanagement

Diverse, fit-for-purpose sources& conservation,promotingwaterwayprotection

Adaptive, multi-functional

infrastructure &urban designreinforcingwater sensitivebehaviours

Service Delivery Functions

Water supplyaccess &security

Public healthprotection

Floodprotection

Social amenity,environmentalprotection

Limits onnaturalresources

Intergenerationalequity, resilienceto climatechange

Cumulative Socio-Political Drivers

ARSIT

4. Progressive Urban Water Management

Well-balanced Hydrological System

● Applied for a unit of River Basin

● Well-balanced among Flood Control,

Water Use and Aqua-environment

● Promotion of Rainwater Storage and

Infiltration Facilities

Japan

Country-specific Approaches for Sound Water Cycle

11

ARSIT

4. Progressive Urban Water Management

BMP(Best Management Practices)

● Low Impact Development (LID)● Prevent or Reduce Pollution● Protect Water Quality● Promotion of Wetland , Pond , Infiltration , Porous Pavement

USA

12

RHM(Rainwater Harvesting Management) in Green Growth(Policy of Government)

● Integrated Management of Rainwater● Environmentally Friendly Techniques(Green Space & Rainwater Harvesting)

● Promotion of Rainwater Storage andInfiltration Facilities

Korea

ARSIT

4. Progressive Urban Water Management

Germany

13

SUDS(Sustainable Urban Drainage Systems)

● Integrated Design(Quantity, Quality & Amenity)

● Site Management (Design, Maintenance & Education)

● Permeable surface, Filter strips & swales,and Infiltration devices

● Basins and Ponds

UK

DUD(Decentralized Urban Design)● Decentralized Rainwater Management byArcology

● Management of StormwaterRunoff

ARSIT

4. Progressive Urban Water Management

WSUD(Water Sensitive Urban Design)

● Urban Water Cycle Management(Water supply, Stormwatercontrol,Treated sewage)

● Source Control● StormwaterReuse(ex. Rainwater tanks)● Reducing Flows(ex. Detention basin, Infiltration systems)

● Water Conservation(ex. Water saving fixture, Greywaterreuse)

● Redirecting Flow(Pipe, Drain and Channel)● Water Quality Treatment

Australia

14

ARSIT

4. Progressive Urban Water Management

Location of Yanase River Basin

Tokyo Bay

ＴｏｋｙｏＢａｙ

Yanase River(Tributary of Shingasi River)Catchment Area:100km2

River Length:20km

15

Population130,000 in 1961630,000 in 2007

ARSIT

5．Master & Action Plan for Sound Water Cycle

Water Cycle has been deteriorated in River Basin due to Urbanization

FloodingDepletion ofSpring

Rainfall

Urbanized Condition

Lowering of Groundwater Level

16

ARSIT

5．Master & Action Plan for Sound Water Cycle

17

Co-operative System for Drafting Master Plan

n For building the consensus of the plan

Investigative Committee

Academic AdvisersGovernment OfficersRepresentative Citizens

Citizen's Meeting

More than 100 CitizensGovernment Officers

Mutual Adjusting Meeting

Ministry of Land,Infrastructure and TransportRelevant Local Governments

Home PageDirect Mail

Symposium, SeminerFestival

Exchangeof Information

ARSIT

5．Master & Action Plan for Sound Water Cycle

18

Mutual Adjusting Meeting by Local Governments

n For building the consensus of the plan

Meeting by Relevant Government Officers

National Gov.2 Prefectures8 Citiesin a same river basin (Yanase)

ARSIT

5．Master & Action Plan for Sound Water Cycle

Members

19

Citizen’s Meetingn For building the consensus of the plan

Discussion in the meeting

Field Survey

ARSIT

5．Master & Action Plan for Sound Water Cycle

Fundamental Principles

20

Preservationof Green Land

&Farm Land

3 principal pillars of main measures

Promotion ofRainwater Storage & InfiltrationFacilities

Promotion of Civic Activity

For the attractive basinbased on our cooperative activities

linking with inhabitants,water and green zones

ARSIT

5．Master & Action Plan for Sound Water Cycle

21

【Individual Approach】

1st. pillar : Preservation of Green Land & Farm Land

1. Increase of Public Domain Green Land2. Private Green Land opened to Public3. Increase of designated forest by government4. Promotion of private farmland

carried by government

Private FarmlandDesignated TreePrivate Green Land opened to Public

Public Domain Land

ARSIT

5．Master & Action Plan for Sound Water Cycle

22

【Individual Approach】

2nd. pillar : Promotion of Rainwater Storageand Infiltration Facilities

1. Set up rainwater storage and infiltration facilities in a basin as many as possible

2. Promote rainwater storage and infiltration facilities3. Give publicity for rainwater storage and infiltration

facilities

Rainwater Storage on School YardRainwater Utilization

Event for PR

ARSIT

5．Master & Action Plan for Sound Water Cycle

23

【Individual Approach】

3rd. pillar : Promotion of Civic Activity

1. Promotion of Supporting System for Civic Activity2. Cooperation among Local Governments and Citizens

Social Gathering organizedby Government Clean up Activity

ARSIT

5．Master & Action Plan for Sound Water Cycle

Execution Method for Action PlanConventional Method:Set up the action plan annually based on the budget by local government for required actions and measures until the target year.

New Method in this time:Start with what we can do and execute experimentally and change the direction if there is a problem.

24

ARSIT

5．Master & Action Plan for Sound Water Cycle

25

ARSIT

6．Conclusive Comments

It is recognized that the water-related issues such as flooding and water shortage will be serious in the 21st century in the whole world.

In order to solve this serious problem, it is inevitable to think of not only conventional flood control, sufficient water supply, but also water environment which involves global warming induced by carbon dioxide.

We believe that the promotion of rainwater storage and infiltration facilities will much contribute to the well-balanced hydrological system and the prevention of global warming.

In order to achieve the well-balanced hydrological system by the action program, the strong leadership and financial support from the national government is required.

Thank you for your attention

ARSIT

26