Presentation Outline

Current Status and Future of Urban Stormwater Management on Wastewater System in Japan Takashi Sakakibara Infrastructure Management, Japan 2010 Water Korea 1

Presentation Outline Current Status Increase of heavy rainfall frequency Big Gap between designed d and max. recorded d rainfall Future Direction Strategy Hot topics-tsurumi River,Radar system, Inundation Hazard map, Public Relations Infrastructure Management 2

Increase of heavy rainfall frequency Number of cases of more than 50mm hourly precipitation Projected number of days with more than 100mm precipitation 公助によるハ ド対策 Source: Climate Change Adaptation Strategies to Cope with Water-related Disasters due to Global Warming ( MLIT, 2008) and Wise Adaptation to Climate Change (MOE, 2008) Infrastructure Management 3

Type of heavy rainfall 公助によるハ ド対策 Infrastructure Management 4

Big Gap between Design and Max. recorded rainfall Design: Rainfall intensity 35-66.8 mm/hr Return Period 3-10 years Max. recorded events Rainfall intensity 50-131 mm/hr Return Period >100 years Ratio of area coverage 41-89 % City Design level of sewerage system Actual rainfall events (largest recorded) Ratio of Area Coverage against design rainfall Rainfall intensity Return Rainfall intensity Return mm/hr period mm/hr period % Sapporo 35.0 10 50.2 50 85.6 Sendai 52.2 10 94.3 >100 55 Niigata 49.9 10 97.0 >100 51.8 Chiba 53.4 10 71.0 50 72.8 Saitama 65.7 10 81.0 30 41.4 Tokyo 50.00 3 131.0 >100 85 Kawasaki 57.9 10 117.0 >100 54.7 Yokohama 57.9 10 92.0 100 61 Shizuoka 66.8 7 111.5 >100 48.5 Hamamatu 58.9 7 72.5 20 46.3 Nagoya 60.3 10 97.0 80-100 93.1 Kyoto 61.5 10 88.0 100 89.7 Osaka 60.0 10 77.5 40 87.3 Sakai 48.4 10 93.5 >100 80.1 Kobe 49.1 10 87.7 >100 72.1 Hiroshima 52.9 10 81.0 >100 62.8 Kitakyushu 53.1 10 101.0 >100 67.5 Fukuoka 59.1 10 116.0 >100 79.3 Infrastructure Management 5

Inundation Damage Coverage ratio of inundation protection Average 50%(FY2007) High priority Area 24%(FY2007) June 29,1999 Fukuoka City Hakata Station flood d level l over the floor flood level under the floor Infrastructure Management 6

Strategy for Urban Stormwater Management self/cooperative- defense SlfDf Self-Defence soft hard Infrastructure Management 7

Tsurumi River*(1) Detention Basin/Reservoir by River Works *designated by Designated Urban River Inundation Prevention Act in 2005 公助によるハ ド対策 Tokyo Kanagawa Chiba Ykh Yokohama Nissan Stadium 3.9million m3(total) Infrastructure Management 8

Tsurumi River(2) Stormwater Reservoir Pipe by Sewage Works Egawa 81,000 m3 Kawasaki City Shibukawa 144,000 m3 Area with gravity flow Area with pump drainage Drainage area border Municipalities border Reservoir Pipe Name of pump drainage Name of freservoir Pipe 公助によるハ ド対策 Kozukue-Chiwaka 256,000 m3 Yokohama City Nippa-Suehiro 410,000 m3 Infrastructure Management 9

New Quick Plan for Stormwater Control Period 2004-2008 Budget 60 billion JPY 50mm/hr for 25 High-priority area with 50mm/hr 26 Small area 8 Pumping area 70mm/hr for 4 underground area Source: Tokyo Metropolitan Gov. (2004) 10 Infrastructure Management 10

Statistical Figures Off-site Reservoir* N=788 V=1.3 million m3 On-site Storage N=392 V= 97,000 m3 (park) N=12,303 V= 34,000 m3 (household) On-site infiltration N=200,000~ V=230,000 m3 (inlet) N=120,000~ V= 80,000 m3 (trench) N=80,000~ V= 16,000 m3 (Misc.) *including Combination with CSO control,temporal facilities Source: Sewerage Census 2008 (JSWA 2010) Infrastructure Management 11

Configuration Tokyo Amesh 2 Radars and 150 ground raingauges Open on Web 2002 Renewal 2007 Resolution Frequency Coverage 250m~500m~1,000m every 5min N-S 120km E-W 190km Cooperation with Saitama Pref., Kawasaki City and Yokohama City Source: Tokyo Amesh web site(2009) Infrastructure Management 12

Real Time Control in Umeda Pumping Station, Tokyo Combined Sewer System Area (1.1km2) 34 rainfall events from 2005 to 2006 19% reduction for total CSO volume and 27% for BOD load Raingauges 公助によるハ ド対策 Water level sensors Tokyo Amesh Model Unit Umeda PS WWF pump p Radar RTC System Control Unit WTP DWF pmup Source: Kuno and Suzuki (2009) Infrastructure Management 13

X-band Multi Parameter e Radars Without ground raingauge Resolution 250-500m Frequency 1 Min Coverage 60km Forecasting weather, runoff and inundation Source: Tsuchiya and MLIT(2009) Hokuriku:2 stations Kinki:4 stations Ch b 3 t ti Kanto :2 stations Chubu:3 stations Infrastructure Management 14

Inundation Hazard Map Most of all 1,774 municipalities should prepare a hazard map only 123 municipalities prepared (as of Mar.2010) MLIT revised the design manual to enhance the preparation Source: MLIT(2009) Infrastructure Management 15

Public Relations Many Reservoirs welcomed people during/after construction Left: Site Visit i Tour by elementary School(Saitama City, 2006) Right: Underground Temple - Metropolitan Area Outer Underground d Discharge Channel Infrastructure Management 16

Rainwater Harvesting(1) Name of facilities Constructed year Storage capacity (m 3 ) Roof catchment area (m 2 ) New Hiroshima Stadium 2009 1,000 23,000 Saitama Super Arena Tokyo Dome Yokohama Stadium Nagoya Dome Osaka Dome Fukuoka Dome Saitama Stadium 2002 2001 3,250 29,000 Saitama Super Arena 2000 1,200 28,000 Sendai Dome 2000 1,300 19,800 Yokohama Stadiuam 1998 2,000 30,000 Tajima Dome 1998 3,000 19,000 Kitakyushu Media Dome 1998 2,000 22,000 Nagoya Dome 1997 2,800 35,000 Osaka Dome 1997 1,700 31,400 Ohdate Extensive forest Dome 1997 4,320 21,000 Fukuoka Dome 1993 2,900 34,000 Izumo Dome 1992 1,210 36,000 Akita Sky Dome 1990 1,200 12,000 Green Dome Maebashi 1990 1,120 20,000 Tokyo Dome 1988 1,000 15,700 Source: Furumai and Okui (2010) 17

Rainwater Harvesting(2) Hiroshima StadiumInflow pipe Inflow from outside of Stadium (Catchment area:52ha) Inflow manhole Storage for runoff control Ohzu WWTP 1000m 3 storage capacity for rainwater harvesting Watering playground 7,000 2= 14,000m 3 Flushing toilet Amenity and landscape water 公助による Stream ハ ド対策 Underground Source: Furumai and Okui (2010) storage tank Infrastructure Management 18

Conclusion Big Cities are on the way to the design target of 3-10 yeas for return period and 35-65.7mm/hr. Should consider the max. recorded rainfall exceed 100 years and over 100 mm/hr. New strategic t challenge - cooperation of Hard, Self/Cooperative-Defense and Soft - is needed. Radar system and Inundation Hazard map are smart tools for Soft measures. Infrastructure Management 19

Thank you for your kind attention! The author wishes to thank the staff at municipalities who helped with the research. Infrastructure Management 20