Comprehensive Urban River Basin Management in Japan Regional Workshop on Climate Change and Urban Flood Management March 19-20, 2013 Daegu, Republic of Korea ARSIT Association for Rainwater Storage & Infiltration Technology Masahiro IMBE 1
Today s Presentation 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 2
1.Direction of Comprehensive Urban River Basin Management in Japan (Flood Control) Comprehensive Mitigation Measures against Flood Damage proposed by the River Council in 1977 Well-balanced condition of flood control, effective rainwater utilization & aqua-environmental improvement (Well-balanced Hydrological System) Preservation of Well-balanced Water Cycle Proposed by the River Council in 1996 Rainwater Storage and Infiltration Facilities Legislation of New Act for Urban Inundation Prevention in 2003 Future Direction 3
2.Comprehensive Mitigation Measures against Flood Damage Stormwater Treatment Allotments (Description using Hydrograph) Hydrographfor RiverPlanning 3SewerageAlotment (StorageFacility) RiverFlowDischarge,Q HydrographforSeweragePlanning 5ChannelAlotment (DischargeFacility) <IncludingDischarge From MainStorm Sewer> 2Basin-wideAlotment (ArtificialWaterRetention andretardingfunction) 4RetardingPondAlotment (StorageFacility) Storage Facility DesignFloodDischarge Basin-wide BasicDesignFloodDischarge Basin-wideDesignFloodDischarge 4 Time T
Variety of Comprehensive Mitigation Measures according to Stormwater Treatment Allotments in Basin Conservation of Green Land Conservation of Urbanization Control Area Improvement of River Channel Anti-disaster Reservoir Permeable Pavement Infiltration Facility Retarding Basin Permeable Box Storage Facility Sewarage Storage Floor Elevated Building Play-lot Storage Storage Facility Sewa r a g efa ci l i t y ①Natural Control Function ②Basin-wide Allotment ③Ｓｅｗａｒ ａｇｅ Ａｌ ｌ ｏｔ ｍｅｎｔ ④Regulating Pond Allotment ⑤ＣｈａｎｎｅｌＡｌ ｌ ｏｔ ｍｅｎｔ 5
3. New Act for Urban Inundation Prevention Riverside flood control measures Landside inundation control measures Structural measures River Law (pre-flood measures) Flood control measures including river channels and dams Stormwater retention and infiltration facilities in the river basin (river administrator) Requiring the provision of drainage facilities with retention and infiltration functions (by ordinances) Wastewater drainage and disposal Sewerage Law New act Nonstructural measures Flood Prevention Law (post-flood measures) Designation of inundation hazard areas Designation of urban river Designation of urban flood hazard area and urban river basin and urban inundation hazard area for (ministers, prefectural riverside flood and landside inundation governors) Drawing up of "river basin inundation prevention plan" for comprehensive inundation prevention measures (river administrator, sewerage administrator, prefectural governor, municipal head) 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 by local government Permission for development Town Planning Law 6
3. New Act for Urban Inundation Prevention 2 Retention and infiltration function can be added to drainage facilities of each house in accordance with the ordinance. Conventional Inlet Reduction of Runoff Discharge by adding the Infiltration Function to Conventional Inlet 7
3. New Act for Urban Inundation Prevention 3 It regulates the acts that hamper functions of storm water retention and infiltration Runoff Discharge (Q) After Development without Measures Time Increase due to Development Runoff after Development Runoff before Development Runoff Discharge (Q) Time After Implementation Measures by Storm Water Retention and Infiltration Reduction to the Max. Runoff before Development Runoff Discharge after Implementation 8
3. New Act for Urban Inundation Prevention 4Prefectural governor can designate a large storm water retention pond as the specified pond to be preserved. Existing storm water detention pond (approximately 500 m 3 scale) Overview after landfill 9
4. Progressive Urban Water Management CumulativeSocio-PoliticalDrivers Watersupply access& security Publichealth protection Flood protection Socialamenity, environmental protection Limitson natural resources Intergenerational equity,resilience toclimate change WaterSupply City Sewered City Drained City Waterways City WaterCycle City WaterSensitive City Supply hydraulics (Reference) Separate sewerage schemes Drainage, channelisation ServiceDeliveryFunctions Point& difusesource polution management Diverse,fit-forpurposesources &conservation, promoting waterway protection Urban Water Management Transitions Framework R. Brown, N. Keath and T. Wong, (2008) Transitioning to Water Sensitive Cities: Historical, Current and Future Transition States, 11 th International Conference on Urban Drainage, Edinburgh, Scotland, UK Adaptive,multifunctional infrastructure& urbandesign reinforcing watersensitive behaviours 10
4. Progressive Urban Water Management Country-specific Approaches for Sound Water Cycle Japan Wel-balancedHydrologicalSystem AppliedforaunitofRiverBasin Wel-balancedamongFloodControl, WaterUseandAqua-environment PromotionofRainwaterStorageand InfiltrationFacilities 11
4. Progressive Urban Water Management Korea RHM(RainwaterHarvestingManagement) ingreengrowth(policyofgovernment) IntegratedManagementofRainwater EnvironmentalyFriendlyTechniques (GreenSpace&RainwaterHarvesting) PromotionofRainwaterStorageand InfiltrationFacilities USA BMP(BestManagementPractices) LowImpactDevelopment(LID) PreventorReducePolution ProtectWaterQuality PromotionofWetland,Pond,Infiltration, PorousPavement 12
4. Progressive Urban Water Management SUDS(SustainableUrbanDrainageSystems) UK IntegratedDesign (Quantity,Quality&Amenity) SiteManagement (Design,Maintenance&Education) Permeablesurface,Filterstrips&swales, andinfiltrationdevices BasinsandPonds Germany DUD(DecentralizedUrbanDesign) DecentralizedRainwaterManagementby Arcology ManagementofStormwaterRunof 13
4. Progressive Urban Water Management WSUD(WaterSensitiveUrbanDesign) Australia UrbanWaterCycleManagement (Watersupply,Stormwatercontrol, Treatedsewage) SourceControl StormwaterReuse(ex.Rainwatertanks) ReducingFlows (ex.detentionbasin,infiltrationsystems) WaterConservation (ex.watersavingfixture,greywaterreuse) RedirectingFlow(Pipe,DrainandChannel) WaterQualityTreatment 14
5.Master & Action Plan for Sound Water Cycle Population 130,000 in 1961 630,000 in 2007 Tokyo Bay Yanase River (Tributary of Shingasi River) Catchment Area:100km 2 River Length:20km Tokyo Bay Location of Yanase River Basin 15
5.Master & Action Plan for Sound Water Cycle Water Cycle has been deteriorated in River Basin due to Urbanization Urbanized Condition Rainfall Depletion of Spring Flooding Lowering of Groundwater Level 16
5.Master & Action Plan for Sound Water Cycle Co-operative System for Drafting Master Plan For building the consensus of the plan Investigative Committee Academic Advisers Government Officers Representative Citizens Exchange of Information Citizen's Meeting More than 100 Citizens Government Officers Home Page Direct Mail Symposium, Seminer Festival Mutual Adjusting Meeting Ministry of Land, Infrastructure and Transport Relevant Local Governments 17
5.Master & Action Plan for Sound Water Cycle Mutual Adjusting Meeting by Local Governments For building the consensus of the plan Members National Gov. 2 Prefectures 8 Cities in a same river basin (Yanase) Meeting by Relevant Government Officers 18
5.Master & Action Plan for Sound Water Cycle Citizen s Meeting For building the consensus of the plan Discussion in the meeting Field Survey 19
5.Master & Action Plan for Sound Water Cycle 3 principal pillars of main measures Preservation of Green Land &Farm Land For the attractive basin based on our cooperative activities linking with inhabitants, water and green zones Promotion of Rainwater Storage & Infiltration Facilities Fundamental Principles Promotion of Civic Activity 20
5.Master & Action Plan for Sound Water Cycle 1st. pillar : Preservation of Green Land & Farm Land Individual Approach 1. Increase of Public Domain Green Land 2. Private Green Land opened to Public 3. Increase of designated forest by government 4. Promotion of private farmland carried by government Public Domain Land Private Green Land opened to Public Designated Tree Private Farmland 21
5.Master & Action Plan for Sound Water Cycle 2nd. pillar : Promotion of Rainwater Storage and Infiltration Facilities Individual Approach 1. Set up rainwater storage and infiltration facilities in a basin as many as possible 2. Promote rainwater storage and infiltration facilities 3. Give publicity for rainwater storage and infiltration facilities Rainwater Utilization Rainwater Storage on School Yard Event for PR 22
5.Master & Action Plan for Sound Water Cycle 3rd. pillar : Promotion of Civic Activity Individual Approach 1. Promotion of Supporting System for Civic Activity 2. Cooperation among Local Governments and Citizens Social Gathering organized by Government Clean up Activity 23
5.Master & Action Plan for Sound Water Cycle Execution Method for Action Plan Conventional 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
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 wellbalanced 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. 25
Thank you for your attention 26