Ⅶ SESSION REPORTS Ⅶ-1 Japan Mr. Shin TSUBOKA Director General, National Institute for Land and Infrastructure Management Adaptation to Flood Change Due to Warming in Japan National Institute for Land and Infrastructure Management Director General : Shin Tsuboka Geographic Features and City Formation Most of the plains in Japan are alluvial plains and many cities are formed over these alluvial plains. Alluvial plain Alluvial plain Tokyo area Chukyo area （The Kanto Plain） （The Noubi plain） 1 2－1 Flood Vulnerability Tokyo and Edo river, Ara river and Sumida river Elevation Keihin- Tohoku Musashino line Line Ayase Shin Route 6 Sumida river saka Naka river Oba Edo Saka river riverJoban Ara river river river river Line Kita Adachi Katsushika Misato Matsudo Ward Arakawa Ward Ward City City Ward London and the Thames The Thames Information provided by MLIT The relation of grounds and rivers level in Tokyo and London 2 Flood damages Flood damage density of (100 billion Yen) ordinary assets Damage to ordinary assets (10 thousand yen/ha) Flooded area (10 thousand ha) Flood damage area Flood damage density of ordinary assets such as housing areas (The ratio of assets to an affected area) Ordinary asset damage 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Year Transition of Ordinary asset damages and flooded area 3 2－2 Precipitation change (1) Number of downpour occurrences with 50mm rainfall per hour or larger Total number of occurrences per year (Based on data from about 1,300 locations of AMeDAS stations nationwide) Number of occurrences/Year 1996-2005 1976-1985 1986-1995 288 times 209 times 234 times on average on average on average Number of downpour occurrences with 100 mm rainfall per hour or larger Total number of occurrences per year (Based on data from about 1,300 locations of AMeDAS stations nationwide) Number of occurrences /Year 1976-1985 1986-1995 1996-2005 2.2 times on 2.2 times on 4.7 times on average average average Prepared by MLIT based on data by Japan Meteorological Agency Recent changes in heavy rain frequency based on AMeDAS data by Japan Meteorological Agency 4 Precipitation change (2) 2004 Niigata and Fukushima Heavy Rainfall Daily precipitation was the largest amount of Recorded decade distribution of top 20 largest 1.2 times (421mm) by then precipitation (Observatories of Japan Meteorological Agency) Number of locations 1990～ Daily precipitation Hourly precipitation Precipitation distribution map Year Most of the largest precipitation events in various areas in Japan were recorded after 1990. Levee breach (Kariyata River) 5 2－3 Changes in Sea Surface Level and their influences Tokyo Bay Yokohama City-Chiba City 1.76 million 2.7 million people Water level change level Water people (Currently) (After sea level rise) Year Changes in sea surface in Change in the under sea surface Japan’s coastal areas area in Tokyo Bay in the case of rise of 0.59m 6 Transition national budget concerning public works (Trillion Yen) Ratios of the public works expense to the general account budgets (Initial) Extra budget Extra Initial (Fiscal year) 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 Basic plan for public investment The initial budgets decreased (Initial plan :430 trillion yen from fiscal 1991 to 2000) for 6 straight years. Data:Road-related budget for fiscal 2007【MLIT Press Release (January, 2007) 】 7 2－4 Coming of Depopulating Society 【Long-term transition of the total population of Japan】 (10,000 people) Peaked in Dec, (2000) 2004(127.83 million ) About 1 in 5 persons is 126.93 million elderly. 121.14 million in 2025 About 1 in 4 persons is elderly. World WarWorld II End of the 100.59 million in 2050 About 1 in 3 persons is elderly. Nationwide Meiji Restoration (High estimation) Kyoho Reform 71.99 81.76 million million Edo Shogunate Establishment of (1945) Nationwide (Medium estimation) 64.14 million Shogunate of Kamakura Establishment Shogunate of Muromach Establishment About 1 in 3 persons is elderly. 31.28 33.30 million million Nationwide (1868) (1716-45) (Low estimation) 12.27 46.45 million million 7.57 8.18 million million (1603) (1192) (1338) Year (Source) Prepared by National and Regional Planning Bureau of MLIT based on data from National Institute of Population and Social Security Research Worry ･ Uncertainty about the future is growing in minds of Japanese peoples 8 Adaptation Measures in Terms of Structure (1) Understanding of soil mechanics of embankment body by boring Boring Machine 【Riverside】 【Landside】 Water level of the river Embankment body Fine soil layer Sand layer Sampling Investigation of caves in storm surge barriers (Radar exploration of underground objects) Exploratory device Antenna Bank protection / Floor slab Caves Implementation of dike inspections 9 2－5 Adaptation Measures in Terms of Structure(2) Kirigaoka retarding basin (Tsurumi River) Normally At the time of flood Utilization of multipurpose storage facilities 10 Adaptation Measures in Terms of Land Use Revision Floor height Structural Diagram of 1st story limitation Wooden N･P (+) 4 m buildings are or more prohibited Rooms for human N・P (+)1m occupation must or more be on the 2nd or higher stories. N・P (+)1m − or more Example of Restrictions under Ordinance (Nagoya City) －Hazardous areas designation based on Building Standard Law － 11 2－6 Adaptation Measures in Terms of Damage Reduction Measures (1) Effect of the Completion of Second-line Bank ←Yoshida R. R.→ se aru ank Flooding N ne B nd-li Seco T o S h a o n k n u o l u i n e e D Flooding i s c h a r g e Reduced C Damage in a n Central a l Kashimadai Town 46 3 te ou R Segment in Service Area Affected by Flood in August 1986 The construction of second-line bank in this district is promoted combined with a road project (bypass construction). Flood Flow Control Using Second-line Banks 12 Adaptation Measures in Terms of Damage Reduction Measures (2) Improvement and Water level gauge Maintenance of Information offer System Relay station Improvement and maintenance of Rain gauge Surveillance camera observation equipment such as rain gauges, Regional surveillance cameras, Development Bureau etc. and Municipalities Preparation of Flood Hazard Map Preparation and publication of flood Evacuation hazard maps based direction Evacuation on the area where center flood is expected. An example of a hazard map (Kurume City) Implementation of required information offer for safe evacuation such as preparation and publication of hazard maps 13 2－7 For Safe and Secure Local Communities against Natural Disasters Social Capital People can rely on and help each other. Knowledge Information People have System sufficient knowledge Necessary information concerning natural can be obtained when disasters on a routine necessary. basis. Resistance capacity / Restoration capability Resistance capacity enlarged and they are capable of restoration. Four basic elements for safe and secure local communities 14 Management Cycle of Activities of Disaster Prevention Organizations Knowledge・・・People should have sufficient knowledge about natural disasters. Understanding and Indexing of Achievement Status for Safe and Secure Local Community Do Management Check Plan Cycle Action PDCA Management Cycle related to Activities of Disaster Prevention Organizations 15 2－8 Local Disaster Prevention Capability and Disaster Damage Occurrences September 17, 2007 Frontal heavy rain (Yoneshiro River) The previous second largest Those houses rainfall were located Average rainfall of upstream basin in Futatui (Yoneshiro River) outside the 2007 for 24 hours (Unit:mm) Amount of rainfall flooded area and suffered no damage. The previous highest water level Most of the flooded （ ） Futatsui July, 1972 2007 8.07m The previous highest (Yoneshiro River) water level 7.96m Area is arable land. The planned water level 7.385m August, 1947 The highest water level Danger of flooding 6.85m water level 5.9m Warning water level 4.50m Designated water level 3.50m Illustration of the （：Flooded area） flooded areas 16 Examples of Support Activities by NILIM for Improvement of Disaster Prevention Capabilities of Local Communities (1) Support for planning Small and Medium-Sized Companies BCP（Business Continuity Plan） Opinion exchange about common items / BCP planning Consensus building by each ・Damage anticipation company ・Mutual assistance activities, etc Opinion collection, Improvement of business Training and and planning Checking :Exchange of opinions and their review at skull sessions 【 Members of the skull session 】 Chamber of Commerce, Representative Company, Offices of municipalities and prefectures, Regional work offices of MLIT, NILIM, etc A scene from a planning meeting Procedure of BCP preparation support 17 2－9 Examples of Support Activities by NILIM for Improvement of Disaster Prevention Capabilities of Local Communities (2) Development of the animated hazard map and cooperation with local communities Entry of a person’s house, his or her evacuation place and Starting of evacuation as evacuation route. inundation area expands Evacuation route (Person B’s (Person B) Evacuation house) place B B A Starting of A animation (Person A’s house) Evacuation route (Person A) 39 minutes later aprox. 42 minutes later aprox. Person B B B A Person A was A safely caught in reached the the tsunami evacuation wave. place. 18 Conclusion 1) Japan has many cities over alluvial plains and vulnerable structure to flooding. 2) Because of global warming, extreme precipitation in Japan is expected to increase. 3) As adaptation measures, improvement and development of structures are important but have limitations. So it is necessary to improve damage reduction capability of local communities against flooding. 4) National Institute for Land and Infrastructure Management has implemented researches for various technical tasks.