River Basin Management in -Flood Control Measures, Water Resources Management-

Hitomi Godou

Director of River Information Office, River Bureau Ministry of Land, Infrastructure, Transport and Tourism Contents • Flood Control Measures – Related Laws • River Law • Law on Measures against Inundation Damages in Designated Urban Rivers – Examples of River Basin Management () – Non-structural measures • Collection and Provision of River Information

• Water Resources Management – Related Laws • Water Resources Development Law Non-structural measures – Recent trend of water resources • Climate Change • Integrated Water Resource Management History of the River Act

1896 1964 1997

Establishment of integrated Birth of modern river Establishment of systems for systematic flood river management system for management system flood management, water management and water utilization and environmental utilization conservation

・ ・ Improvement and conservation of river Introduction of integrated environment management system for river ・ Introduction of a system for river systems planning reflecting the opinions of local ・ Establishment of water community utilization rules and regulations

Flood management Water utilization

Flood management Flood management＋ Water utilization

Environment Transition from the old system to the new system due to the River Law amendment

Content: basic policy; design flood; River works River

river works river design flood discharge, etc.; major river work items Master plan for

Drafting of master plan for river works

Old system River Council Opinion ( systems)

Adoption of master plan for river works plan Content: basic policy, design flood, Content: goal of river improvement, river works, improvement design flood discharge, etc. scope of river maintenance River works, River River improvement improvement River Basic policy for river Basic policy for river river maintenance river Draft

Opinion Academic experts Drafting of basic policy Infrastructure for river improvement Development Council Reflecting public opinions (Class A river systems) Opinion by, for example, New system Prefectural river councils Adoption of draft river holding public hearings Opinion (Class B river systems) improvement plan Adoption and announcement of basic policy Head of local government for river improvement Opinion Only if there is a prefectural Adoption and announcement river council of river improvement plan 4 River Administrator (Prefectures, municipalities) Local Government Municipalities) Local Government River Administrator River (National Gov’t, Prefectures, banking, dredging) banking, rainwater infiltration inlets inlets infiltration rainwater and discharge channels and discharge Preservation of urbanization control are control of urbanization Preservation of natural lands Preservation ponds of food control Construction of rainwaterConstruction storage and pavements of permeable Construction into water of draining facilities Development of storage Construction buildings Promotion of flood resistant evacuation and of warning Establishment system control of flood Reinforcement and flood records of inundation Announcement buildings Promotion of flood resistant residents PR to local River improvement (em Construction of dams, retarding basins, basins, of dams, retarding Construction Preservation of urbanization control areas control of urbanization Preservation mound constructing Restriction on ofImprovement farm management z z z z z z rivers z z z systems z z hazard areas z z z z z z z Water Water retarding area retarding retaining area Lowland area Lowland River Measures Reduction Damage System of Comprehensive Flood Control Measures Basin Measures ① ③ Measures ②

Comprehensive Flood Control Measures Outline of Law on Measures against Inundation Damages in Designated Urban Rivers

against flood Structural measures Non-structural measures from rivers Measures River Law Flood Control Law (Prevention of flood) (Countermeasures against flood when it occurs)

Law on Measures against Inundation Damages in Designated Urban Rivers

around rivers Because previous each law has limited enforcement, this law strengthens against flood

Measures countermeasures and assures flood control in river basin.

Sewage Law City Planning Law

○Designate urban river (basin) ・Urban area covers more than 50% of river basin ・Average annual damage (occurred or predicted) exceeds 1 billion yen (=$10mil) ・Because of urbanization, it is difficult to control flood by constructing river facilities or flood control dams ○Formulate river basin flood control plan ・4 members (river and sewage administrators, governors, and mayors) make the plan together ○Implementation of measures 7 Outline of Tsurumi River (Geography)

River basin area 235km2 Hill / tableland 70％ Chiba Pref. Main stream length 42.5km Alluvial lowland 30％

Kanagawa Tsurumi river basin Pref. Riverbed gradient : 1/250

Tsurumi River Tsurumi River

elevation Hayase- Tsurumi Onda River River River 0～20m

Toriyama River

Riverbed gradient ：1/1,000 Outline of Tsurumi River (Urbanization and population increase)

Urbanization ration has increased Rapid economic growth has turned natural area into urban area by 75% in 50years 1958 10％ 1958 10 1966 20%

Typhoon Karinogawa in Sep 1958 450,000 700,000

1975 60% Present 85%

Typhoon No.17 in Sep 1976 1,200,000 1,880,000

Natural Area Urbanization Urbanization Population Urban Area OutlineOutline ofof TsurumiTsurumi RiverRiver (Effect(Effect ofof urbanization)urbanization)

・Population increased by Function of keeping and retarding water became weakened 1.4 million in 50 years

・85% of river basin area urbanized

・Typical urban river

Before development After development AsAs aa resultresult Slight urbanization Significant urbanization 1,300 m3/s Peak runoff Volume Doubles ・Discharge into river Difference 770 m3/s has become faster Present Runoff reaches ・Peak runoff has Before its peak in becomes bigger Development 1/3 of time

2～3 hours 10 hours River related projects in Tsurumi River Basin inundation control plan

Future flood control

Existing retarding basin

【Administrator】 MLIT Tokyo Metropolitan Kanagawa Prefecture Yokohama City Tsurumi River multi-purpose runoff retardation area

： International Tsurumi River multi-purpose runoff retardation area Stadium Yokohama Tsurumi River levee Overflow-type

Drainage gate of runoff retardation area

T s u r K u ara m suy i ama R Riv iv er e r Specifications for the Tsurumi River multi- purpose runoff retardation area -Service started: June 15, 2003 -Area: 84 ha -Total reservoir capacity: 3.9 million m3 -Floodwater regulation (Temporary channel) Runoff retardation area collects 200 m3/sec. (Planned river channel) Runoff retardation area and floodway collect 700 m3/sec. Sewerage projects in Tsurumi River Basin inundation control plan

Natural drainage area

Pump drainage area (Name)

Rainwater storage tube (Name) RainwaterRainwater storagestorage facilitiesfacilities Development of facilities for target rainfall Planned discharge in pump drainage areas Planned storage of major facilities City Discharge Planned City Storage facility Planned area discharge Storage Yokohama Tsuzuki 17m3/s Yokohama Shin hasue trunk line 410,000m3 3 Kouhoku 142m /s Kozukue chiwaka trunk line 256,000m3 3 Hokubu 189m /s Kawasaki Shibukawa rainwater storage 144,000m3 Kawasaki Kase 55m3/s tube Egawa rainwater storage tube 81,000m3 Total 402m3/s

Pump facilities Rainwater storage tube Present status and problems -Present status of River Basin Management （Present status of flood control reservoir）- Tsurumi river was designated as the first Comprehensive Flood Control River in 1979 to cape with rapid urbanization of river basin

● Flood retarding pond As a Result

About 3,300 facilities

Total volume 270 million m3

But more retarding ponds are necessary Storage,Storage, infiltrationinfiltration andand forestforest conservationconservation Development of rainwater storage and infiltration facilities, conservation of forested areas (Total effect by municipalities : 0.3 million m3)

Storage Storage facilities in schools, Infiltration Infiltration by permeable pavement parks and public houses

Infiltration Inlet Infiltration trench

Forest Conservation Infiltration Inlet Infiltration trench

◆Purchase and conservation of forest in developing area Measures against inundation damage -Improvement of collecting and providing river information - Providing necessary information, quick emergency response and minimizing damages in case of flood.

Providing information to the public ■Collecting Information ▼Home Page ▼Mobile Phone ▼Information Board

Gauging station

Monitoring Rain-gauge station camera

Gauging station Patrol

Monitoring camera River Management Office (MLIT) Flood Fighting Activity

Evacuation facility

Municipal Evacuation call Office

Providing Information Evacuation call Water level and Rainfall observation by Telemeter

ProvidingProviding WaterWater levellevel andand RainfallRainfall collectedcollected of of byby TelemeterTelemeter Rain gauge station

multiplex radio transmission station

Branch office

Water gage station River information provider system

Information provided by the Internet and Mobile phone Location of rainfall observation radar

2626 radar radar stations stations collect, collect, anal analyzeyze and and provide provide rainfall rainfall data data nat nationwideionwide Mt. Hako

Mt. Pinshineri Mt. Muri

Mt. otobe

Mt. Yae Mt. Nishi Mt. Monomi Mt. Shirataka

Mt. Yakushi Hijiri Plateau Mt. Houdatsu Mt. Takasuzu Mt. Akagi Mt. Fuka Mt. Mitsutoge Mt. Ohwa Mt. Gozaisyo Mt. Rakan Mt. Oogusu MT. Takagi Mt. Shaka Mt. Mt. Jyatoge Mt. Myojin Mt. Johgamori Happongi

Mt. Kunimi

▲・・・Weather radar installed by River Bureau Rainfall Radar （Mt. Akagi radar） Outline of River Information provider system ¾ The integrated river information system aims at sharing and standardizing river management data including river water levels and rainfall amounts. ¾ River information systems were originally developed by each regional development bureau. They have been integrated into a national river information system. Regional development bureaus can customize the system based on their requirements. ¾ Software are separated from hardware. Improvement cost and life-cycle cost are reduced. ¾ The system also provides rainfall forecasts of Japan Meteorological Agency and rainfall data of the Road Bureau. Strengthen observation of localized heavy rainfall and information service

Upgrading rainfall forecast in corporation with related organizations

Area with Aim at early flood prediction for localized heavy rainfall by resolution of 250m establishment of Rainfall Prediction Model considering localized rainfall development and movement by corporation 6 ut with institutions concern bo a m 0k Observation by X-band radar system ・Locate radar in a triangular shape in urban area ・High resolution and real-time rainfall observation within 60km range from radar ・Furthermore, prediction accuracy is improved by three-dimensional observation of rainfall within the triangle area Location of Rainfall observation by weather radar Rainfall observation by current C-band radar X-band radar Initial stage of rainfall Heavy rain level Image of X-band radar system Hail Glowing cloud

Raindrop Generation Raindrop glow Raindrop Image of glow cumulonimbus glow glow Wind Start raining Heavy Rainfall aerosol Time Policies for Water Resources Development -Water Resources Development Basic Plan-

Water Resources Development Basic Plan • Purpose-specific demand forecasts and supply for 7 river system

Japan Water Agency (JWA)

• Established in 1962 to promote water resources development

Kiso木曽川水系 River system

Yodo River淀川水系 system Area 16.7% 83.3% Population 51.2% 48.8% Tone/Ara River system Industrial 利根川・荒川水系 shipments 47.9% 52.1% 豊川水系system 7 River Systems Other regions system regions 吉野川水系

Chikugo筑後川水系 River system Procedure for Enacting Basic Plans under the Water Resources Development Law

Designation of river systems for water resources development

Basic study (water supply prediction survey, etc.)

Deliberation by the Subcommittee on Water Resources Development, National Land Development Council

Preparation of cabinet decision

Relevant Solicitation of Relevant Discussion Stakeholders views prefectures

Cabinet decision Decision by Minister of Land, Infrastructure, Transport and Tourism (MLIT) Effect of Basic Plans (Tone/Ara River System) Minimizing the Gap between Demand and Supply

250 Planned water supply volume Vested water volume (domestic water and industrial water) Predicted demand and target value for supply 200 Phase II Full Plan (1970 - 1975) Phase IV Full Plan (1988 - 2000) system Tone River system and

/ s) 150 Phase III Full Plan (1976 - 1985) Ara River system 3 Phase 1 Full Plan Tone River system and (1963 - 1970) Ara River system Tone River system 100 Water volume (m

50

0 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 Year

- Planned water supply volume: Volume of water developed by dams, etc. (not including facilities under construction and water diverted under agricultural rationalization projects in the winter.) - Vested water volume: sum of secured water rights and provisional water rights Variability of extreme events is increasing due to climate change

( mm ) In Japan 2,100 2,000 Annual Precipitation 1,900 1,800 1,700 1,600 1,500 1,400 Annual Precipitation 1,300 1,200 Average rainfall trend 1,100 Variability 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 Climate change prediction —Snowfall—

Snowfall will dramatically decrease In a 100 years’ time, the upstream in the northern regions. catchments of the Tone River will have considerably less snow depth.

Snow（cm） depth (cm) 300300 現況 Present: Avg. of 1992–2006 250250 将来 Future: Predictions for 100 yrs. hence

200200 積 雪150150 深

100100

5050 Converted equivalent rainfall (mm) rainfall equivalent Converted

00 10月1日 11月1日 12月1日 1月1日 2月1日 3月1日 4月1日 5月1日 Oct. Nov. Dec. Jan. Feb. Mar. Apr. May （注） 1. 現在は、1992～2006年の積雪深の平均値 Changes in annual snowfall 2. 将来は、約100年後（Model:RCM20、A2）Snow depth changes (avg. of 2081‐2100) ‐ (avg. of 1981‐2000) expected 100 years hence (Fujiwara)

Source: Global warming projection vol. 6 (JMA) Prolonged droughts are expected due to climate change

River Dam Irrigation period Drought periods Drought periods at Basin pattern at present state around 2050 (days/10yrs) (days/10yrs) Ishikari Taisetsu Advanced by 0-10 About 60 days About 30-70 days days Chubetsu Advanced by 0-10 About 30 days About 130-180 days days Tone 8 dams Advanced by 0-40 About 30 days About 100-110 days days Deferred by 0-60 days About 30 days About 90-120 days Chikugo Matsubara/ Advanced by 0-5 days About 50 days About 70 days Shimouke Deferred by 0-30 days About 50 days About 70-80 days

Droughts mitigated Droughts exacerbated Impacts of Climate Change on water quality due to climate change

Use of fossil Global warming fuel, etc.

Water temperature rise Shifts in Changing Temperature rise (remaining warm) precipitation patterns nitrogen cycle in the atmosphere Increase of Fixed thermocline Decrease of winter ice cover E. coli position (increasing light transmission) Landslide in Flux into forests/soil From urban areas rain storm (nitrogen saturation) ← increased diffusion of Decreasing Increase of pests nitrogen/phosphorus↓ circulation in lakes NO -N leaking into Phytoplankton proliferation 3 rivers upstream Soil erosion Savory water Bottom sedimentation Risk of infectious of remains

diseases Increased Products of treatment Turbidity turbidity Increasing pesticide leaks with Decrease of their increased use bottom-layer DO Smell/ Leaking iron/ taste Water safety manganese Leaking hazardous Decrease of river DO Color substances Flux of hazardous substances Water safety Basic point of view for promoting IWRM Addressing adaptation to climate change and social change

Addressing climate Policy Framework to ensure adaptation change to climate change through IWRM

PreparedPrepared forfor moremore frequent,frequent, extremeextreme eventsevents IntegratingIntegrating managementmanagement ofof waterwater demanddemand andand supplysupply CopingCoping withwith changedchanged hydrological/hydrological/ environmentalenvironmental IntegratingIntegrating waterwater facilityfacility planning,planning, situationsituation designingdesigning andand operationoperation Addressing Social needs InformationInformation sharingsharing andand stakeholders’stakeholders’ participationparticipation CoordinatedCoordinated useuse ofof waterwater resourcesresources IntegratingIntegrating managementmanagement ofof surfacesurface waterwater andand groundground waterwater EnsuringEnsuring safesafe waterwater supplysupply IntegratingIntegrating managementmanagement ofof waterwater andand sanitationsanitation quantityquantity andand qualityquality Information sharing and stakeholders’ participation

Information system to involve stakeholders in IWRM: In decision making, consensus building, awareness raising , etc. for adaptation action to climate change. Rainfall, climate, etc Dam data Treatment plant Dam

city DB DB DB

Water quality/ flow data Wastewater DB treatment plant Internet groundwater level observation DB

factory user Development of Intake amount a clearing house

Sea Simulation on integrated water resources management Integrating monitoring, withdrawal, and recharge of surface water and ground water

Required sub-action Surface water 9Policy and regulatory River framework 9Groundwater Monitoring and assessment 9Groundwater level 9Groundwater quality Sewage 9Withdrawal amount treatment

9Coordination mechanism Groundwater between managers 9Information Sharing System Integrated management of water quantity and quality

Effective management by many stakeholders for effective and smooth implementation. Conservation of forests Dam operationLake to keep and watersheds required water quality

Dam Sewage water recycling On-site river water City treatment Water intake plant Environmental Treatment control point plant Discharge regulation Changing intake location Factories/ Businesses Community-based Bypass water environment channel conservation Weir

Sea Environmental flow