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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
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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
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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)
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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.
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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
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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.
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3. New Act for Urban Inundation Prevention
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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
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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
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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
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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
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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
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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
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Population130,000 in 1961630,000 in 2007
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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
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5.Master & Action Plan for Sound Water Cycle
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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
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5.Master & Action Plan for Sound Water Cycle
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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)
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5.Master & Action Plan for Sound Water Cycle
Members
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Citizen’s Meetingn For building the consensus of the plan
Discussion in the meeting
Field Survey
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5.Master & Action Plan for Sound Water Cycle
Fundamental Principles
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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
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5.Master & Action Plan for Sound Water Cycle
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【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
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【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
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5.Master & Action Plan for Sound Water Cycle
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【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.
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5.Master & Action Plan for Sound Water Cycle
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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.
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