Ministry of Land, Infrastructure, Transport and Tourism

1. 's basic flood protection system

2. Preparedness for major floods

・Past major floods and state-level efforts ・Role of MLIT

8 Ministry of Land, Infrastructure, Flood caused by Typhoon Kathleen (1947) Transport and Tourism

Inundation due to a breach in the right-bank levee of the in the Shinkawadori area in Azuma-mura (present-day Watarase River Otone-machi), Higashi-mura (present-day Otone-machi) Chiba Saitama Gunma Ibaraki Tochigi Total

Tone River Dead 8 4 86 592 58 352 1,100 (persons)

Injured 138 1,394 315 23 550 2,420 (persons)

Tone River Number of completely or partially destroyed houses: 31,381 House inundation: 303,160 houses Farmland inundation: 176,789 ha

Flooding in Kurihashi-machi, Saitama

Naka River Edo River ３５０ｍ

Satte-machi, Saitama, submerged in turbid water (Satte City)

Sept. 19 Katsushika-ku Submerged Legend in 3 m water water depth: less than 50 cm water depth: 50 cm to 2 m water depth: 2 m or more

Tokyo 9 Ministry of Land, Infrastructure, Storm surge caused by Ise Bay Typhoon (1959) Transport and Tourism

Flood damage in Aichi and Mie prefectures caused by Ise Bay Typhoon Gifu City National total Aichi and Mie Shinkansen Number of people killed or missing 5,012 4,533 91% Number of injured people 69,538 63,670 92% Number of affected people J 1,887,723 1,110,057 59% way R ess Number of totally or partially destroyed houses xpr T 177,574 125,591 71% in E o ish k Me a Number of houses washed away 16,580 15,386 93% id Searching a stranded house o Number of flooded houses 359,178 196,256 55% L in e Farmland washed away or buried 14,662hectare 6,325ha 43% Farmland submerged 295,264hectare 89,503ha 32% Nagoya City Estimated amount of damage ¥47,857,470,000 ¥13,189,080,000 30% Number of boats/ships washed away or sunk 2,481 2,069 83% T o m e i Kuwana E i x a p City s re n s a e s n Yoro-cho, Gifu (Web site of K i w a L Tokai City Chiryu City y Gifu Prefectural Government) R J People stranded on the Yokkaichi second floor of a house City Chita City Okazaki City Anjo City S Takahama h R in ou City kan t e Handa City sen 1 Suzuka Tokoname Nishio City City 3 City Toyokawa City 2 Gamagori City e te in u L o e R s I Toyohashi City Ise Bay R Minami-ku, Nagoya City J (Ise Bay Typhoon Tsu City Record Book compiled by Nagoya City) Hisai City

Matsusaka City Inundation area 10 Ministry of Land, Infrastructure, History of river improvement Transport and Tourism

1945 1950 1955 1960 1965 19701975 19801985 1990 1995 2000 2005

1947 1959 1972 1982 1990 1995 2000 2004 Typhoon Kathleen Ise Bay Typhoon Heavy rain in July Typhoon No. 10 Eruption of Mt. Hanshin-Awaji Tokai Heavy Rain Typhoon No. 23 Number of people Number of people Number of people Number of people Unzendake Earthquake Number of people Number of people killed: 1,077 killed: 4,697 killed: 421 killed: 427 Number of people Number of people killed: killed: 10 killed: 95 killed: 38 6,310 Number of people Number of people Number of people Number of people Number of people Number of people Number of people Number of people injured: 1,547 injured: 38,921 injured: 1,056 injured: 1,175 injured: 12 injured: 43,188 injured: 118 injured: 721 Creation of a safe, secure and and secure safe, a of Creation disaster-resistant country Infrastructure Emergency improvement Five-year development in the wake of major post- flood control priority plan war floods programs Measures to cope with beyond-design-basis floods

Comprehensive flood Improvement of relatively small control measures rivers coordinated with urbanization

1964 revision of the River Act 1960 1997 revision of the River Act Establishment of systematic Erosion and Flood 1991 revision of the River Act Establishment of comprehensive river river management system Control Emergency Super levees (high-standard levees) system designed for flood control, water designed for flood control and Measures Act utilization and environmental conservation water utilization

2003 2001 revision of the Flood 1949 Protection Act Urban Flood Protection Act Flood Protection Act Establishment of inundation 2005 revision of the Flood hazard area system Protection Act Improvement of system for providing flood information 11 Ministry of Land, Infrastructure, Characteristics of flood damage in recent years Transport and Tourism

The area of inundation has decreased, but the amount of flood Watershed urbanization causes flood risk to increase. damage shows an increasing trend. As a result of railway and arterial road network construction, which began around The amount of flood damage is on the increase. 1960, watersheds today are crisscrossed with railways and roads. The resultant →Although the area of inundation had been on the decrease because of flood urbanization has caused the water retention and detention functions of the control measures, it has been showing a slightly increasing trend in recent watersheds to decline. years. Mainly because of the urbanization of flood-prone areas and the 1958 2004 increase in flood-vulnerable property, the amount of damage has been Percentage of urbanized area: Percentage of urbanized area: showing a tendency to increase. about 10% about 85% Population: about 450,000 Population: about 1,880,000 水害密度（万円／ha） Flood damage density (10,000 yen/ha) Property一般資産被害額(千億円) damage (100 billion yen) 小田急小 田原線 Nanbu南武線 Line東急東横Tokyu 線 Toyoko Line京 6,000 浸水面積１haあたり 6.0 Odakyu Odawara Line Line Kyuko Keihin Amount of property damage per ha of inundation area (2000 prices) Flooded水害区域面積(万ha) land area (10,000 ha) 東 Line Tokaido 浜 一般資産被害額（平成12年価格） 海 急 ５，５８５ 道 行 市営地下Municipal subway 鉄 線 線

5,000 5.0 Area of flooded Daini Keihin 宅地等の Property一般資産水害密度 damage density Yokohama Line Natural land land in residential 第二京浜(Route 1) （浸水面積あたりの(amount of property damage per 横浜線 areas,水害区域面積 etc Urbanized land unit area of inundation)一般資産被害額） Example: 第一京浜Daiichi Keihin 4,000 4.0 Tsurumi River basin (Route 15) Transportation各年代 間に network 整備さ developed れた交 通 in 網each period ３．９ As runoff increases, the time to peak runoff decreases. 3,000 3.0 Amount一般資産被害額 of property damage Peakピーク時流量 discharge Time from peak precipitation intensity fromTime peakprecipitation

2,000 2.0 After watershed Flood discharge 流域開発後urbanization 洪水流量は 約２倍にhas doubled.倍増 洪 Runoff 水 流 1,000 1.0 量 Peakピーク時流量 discharge

０．７ Before watershed 流域未開発時urbanization

The time to peak 0 0.0 ピーク発生時間discharge has は '7954 55 '80 56 '81 57 '82 58 '83 59 '8460 '85 61 '86 62 '87 63 '88 1 '89 2 '90 3 '91 4 5'92 6 '93 7'94 8 '95 9 '96 10 '97 11 '98 12 '99 13 '00 14 '0115 16'02 17 '03 18 '04 '05 '06 decreased約1/3に短縮 to 1/3. 昭和 平成 Infiltration Notes:注１）値は過去５箇年の平均値である。 1. Averages in the last five years 5５時間 hrs １０時間10 hrs １５時間15 hrs 注２）一般資産被害額及び水害密度には、営業停止損失を含む。2. The amount of property damage and flood damage density include business interruption loss. Time降雨のピーク時からの時間 from peak precipitation intensity 注３）出典：国土交通省河川局「H18水害統計」より。3. Source: 2006 Flood Statistics combined by River Bureau, Ministry of Land, Infrastructure, Transport and Tourism 注４）価格は平成１２年価格である。 4. 2000 prices Increasingly intensive land use (e.g., subways, underground streets) has given rise to new types of inundation damage such as flooding of underground spaces.

If submerged in water, even if only once, electronic Having absorbed water, insulation materials appliances are rendered useless. have become useless. Tokyo Metro's Azabu Juban Station (October, 2004) Fukuoka municipal subway (July, 2003) 12 Ministry of Land, Infrastructure, Increasing frequency of heavy rains: The trend is expected to continue. Transport and Tourism

Both hourly rainfall and daily rainfall tend to increase. In future, precipitation is likely to increase throughout the country.

400 Annual frequency of 50 mm/hour or more precipitation events (per 1,000 locations) Projections of increase in daily precipitation in 100 years 350 354

318 ① Hokkaido 1.24 300 Increase of 250 275 275 ② Tohoku 1.22 ② 245 about244 50% 245 229 232 ① 216 200 205 205 206 ③ Kanto 1.11 191 193 179 181 178 182 182※ 177 171 1998-2007 150 154 159 152 158 H10～19 ④ Hokuriku 1.14 144 149 130 238 events 1988-1997128 平均 回 100 104 107S63～H9 238(average) ⑤ Chubu 1.06 S511976-1987～62 95 177 events93 平均 177(average) 回 ④ 50 平均162162 events 回 ⑥ Kinki 1.07 (average) ③ 0 ⑦ Southern Kii 1.13 S H 10 '76515253545556575859606162631234567891011121314151617181920'77 '78 '79 ‘80 ‘81 ‘82 ‘83 ‘84 ‘85 ‘86 ‘87 ‘88 ‘89 ‘90 ‘91 ‘92 ‘93 ‘94 ‘95 ‘96 ‘97 ‘98 ‘99 ‘00 ‘01 ‘02 ‘03 ‘04 ‘05 ‘06 ‘07 ‘08 ⑧ Sanin 1.11 ⑧ ⑤ Annual frequency of 100 mm/hour or more precipitation events (per 1,000 locations) 8 ⑨ Setouchi 1.10 ⑨ ⑥ 7 ⑩ Southern Shikoku ⑦ Increase of H101998-2007～19 1.11 ⑩ Ratio of increase in precipitation* S631988-1997～H9 3.7 events ⑪ Kyushu 1.07 ⑪ 5 about 100% 55 5 平均 3.7(average) 回 5 S511976-1987～62 2.0 events 3.7 1.2 times or more 4 1.8 events4 平均 2.0(average) 回 4 4 平均 1.8(average) 回 1.1-1.2 times 3 1.0-1.1 times 22 2 2 2 2 22 2 2 ２※ * Maximum daily precipitation 1 1 1 1 1 1 0 0 0 000 0 S51'76 52'77 53'78 54'79 55 56‘80 57‘81 58‘82 59‘83 60 61‘84 62‘85 63‘86 1‘87 2‘88 3 4H‘89 5‘90 6‘91 7‘92 8 9‘93 10‘94 11‘95 12 13‘96 14‘97 15‘98 16‘99 17 18‘00 19‘01 20‘02 ‘03 ‘04 ‘05 ‘06 ‘07 ‘08 The level of flood safety will decline because of a future increase in precipitation. For ・The annual frequency of precipitation events with different hourly precipitations example, in some regions such as Hokkaido and Tohoku, the target level of flood was calculated from AMeDAS data obtained from about 1,300 locations in Japan. 18 ・The 2008 data are data obtained on or before September 2, 2008. safety of 1/100 will decrease to about 1/30 so that the flood safety level will decrease Annual frequency of days with a daily precipitation of 200 mm or more to about 1/3 of the target level. 16

Flood safety level (return period) (return level safety Flood 100 14 Increase of about 50%

Number of daysyear per 3.5 days 5.1 days 年 12 D (1901-1930 average) (1978-2007 average) ecr 間 75 ease 合 10 計 8 日 50 数 6 １/３ 4 25 2 Plan Hokkaido Tohoku Kanto Hokuriku Kinki Kii Southern Sanin Setouchi Shikoku Southern Kyushu 0 計 北 東 関 北 Chubu 中 近 紀 山 瀬 四 九 0 画 海 北 東 陸 部 畿 伊 陰 戸 国 州 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 道 南 内 南 The annual frequency of days with a daily precipitation of 200 mm or more calculated from measurements obtained at 51 locations in Japan. Both values in each year (thin line) and 11-year moving averages (thick line) are shown. (JMA data) 部 部 13 Ministry of Land, Infrastructure, Consecutive occurrence of major flood and mass-movement disasters Transport and Tourism

Heavy rainfall events with a total rainfall exceeding 1,000 mm have occurred almost every year mainly in Kyushu, causing flood and mass-movement disasters. 2004 2005 ・Typhoon No. 14 (Sept. 4 to 6) caused heavy rains with a total rainfall of 1,000 mm or more in southern Kyushu. ・ A record number (10) of typhoons made landfall in Japan (three or more times as many typhoons as in the average year). ・ ・During Typhoon No. 10 (July to August), hourly rainfalls of more than 100 mm were observed in the Shikoku region. In A number of rivers including the Oyodo and Gokase rivers flood, causing serious damage in the Kyushu region. Tokushima Prefecture, a total rainfall of more than 1,000 mm was recorded. ・In the Chugoku region, the bankful stage was exceeded in the Ota and other rivers. ・The Fukui Heavy Rain (July) caused a levee breach along the Asuwa River. Typhoon No. 23 (October) caused levee ◆Typhoon No. 14: Kyushu region: 19 people killed, 3 people missing, 3,960 houses flooded above floor level, breaches and overtopping along the Yura and Maruyama rivers, inflicting tremendous damage in Kyoto, Hyogo and other 5,085 houses flooded below floor level parts of the Kinki region. Chugoku region: 4 people killed, 1,678 houses flooded above floor level, 2,969 houses ◆Fukui Heavy Rain: 4 people killed, 4,052 houses flooded above floor level, 9,674 houses flooded below floor level, etc. flooded below floor level ◆Typhoon No. 23: 43 people killed, 13,041 houses flooded above floor level Distribution of rainfall caused by Typhoon No. 14 Flooding of the Oyodo River Debris flow in the Kamishiiba Stranded bus in a flooded area Funato, Tsuno-cho, Takaoka- (Miyazaki City, Miyazaki) area (Shiiba-son, Miyazaki) gun, Kochi Pref. 870mm Distribution of rainfall caused by Typhoon No. 10

Typhoon台風6号 No. 6

Typhoon台風15号 No. 15 Typhoon台風4号 No. 4

Typhoon台風21号 No. 21 バス

Typhoon台風16号 No. 16

Typhoon台風18号 No. 18 Mikado, Misato-cho,

Typhoon台風23号 No. 23 Higashi-usuki-gun, Ebino, Ebino City, Miyazaki Pref. 1,322mm Fukuhara Asahi, Miyagawa, Typhoon台風22号 No. 22 Miyazaki Pref. 1,307mm

Kamikatsu-cho, Tokushima Miyagawa-mura, Typhoon No. 11 台風11号 50 100 200 400 600 800 1,000 Pref. 1,132mm Mie Pref. 1,200mm Typhoon台風10号 No. 10 Flooding of the Yura River 50 100 200 400 600 800 1,000 (Maizuru City, Kyoto) 2007 2006 ・Typhoon No. 4 (July 2 to 17) caused a total rainfall of more than 1,000 mm in the Kyushu region. Rainfalls more than two times as much as the monthly average were recorded in many areas. ・In parts of the Kyushu region, total rainfalls in seven days from July 18 to July 24 of more than ・The Midori and other rivers flooded to cause tremendous inundation damage in many areas. 1,200 mm were recorded. The Sendai and Komenotsu rivers flooded, causing serious damage in ◆Typhoon No. 4: 3 people killed, 169 houses flooded above floor level, 1,152 houses flooded below floor level southern Kyushu. ・A strong bai-u front in July remained stationary over a large area including the Kyushu and Hokuriku regions, and the heavy rains induced by this front caused floods in many areas. Rainfall distribution on July 2 to 17 ◆July Heavy Rains: 5 people killed, 899 houses flooded above floor level, 2,674 houses flooded Ebino, Ebino City, Mitate, Hinokage-cho, Kagoshima Pref. Miyazaki Pref. below floor level 1,105 mm (130%) 1,058 mm (230%) Distribution of rainfall caused by July Heavy Rains Tawarayama, Nishihara- Yanase, Umaji- Okuchi City, Flooding of the Midori River mura, Kumamoto Pref. mura, Kochi Pref. Kagoshima Pref. (Kosa-machi, Kumamoto) 1,080 mm (160%) 936 mm (160%) Okuchi: 1,122 mm

Tashiro, Kinko-cho, Ikegawa, Niyodogawa-cho, Ebino City, Miyazaki Pref. Debris flow in the Futagawa area Kagoshima Pref. Kochi Pref. Sendai River Debris flow in the Ebino: 1,281 mm 1,018 mm (270%) 929 mm (210%) (Satsuma-cho, Kagoshima) Shimodenakama area (Tarumizu City, Kagoshima) Flood flow in the Midori River 100 200 300 400 600 800 1,000 (Hishikari-cho, Kagoshima) (Kosa-machi, Kumamoto) 14 Ministry of Land, Infrastructure, Damage caused by localized heavy rains Transport and Tourism

Flood damage in 2008 The heavy rains on July 28, 2008, and at the end of August brought about localized heavy rains with an hourly rainfall of more than 100 mm and caused inundation damage in many parts of the country.

Damage caused by the flooding of the Asano River in July, 2008, Flood damage in Okazaki City, Aichi Prefecture, in Ishikawa Prefecture and Nanto City in Toyama Prefecture caused by the heavy rains at the end of August, 2008 Seki River ieRiver Hime uoeRiver Kurobe

Asano River Asano A record hourly rainfall of yb River Oyabe River Iga

h River Sho 146.5 mm (previous Shonai River

Hourly rainfalls of 132 mm and River Kakehashi 一宮 114 mm were recorded at the River Tedori record: 55 mm) was Koinzemi raingauge station observed at the Okazaki Suzuka River Yahagi River oaj River Joganji (Nanto City) and the River Kuzuryu raingauge station (Okazaki Okazaki Shibaharabashi raingauge station City, Aichi Pref.), and Kumozu River Toyo River another record rainfall of (Kanazawa City), respectively. Koinzemi River Jinzu Kushida River Shibaharabashi 120 mm (previous record: 76 mm) was observed at ●Raingauge station ●Raingauge station the Ichinomiya raingauge * Koinzemi raingauge station (MLIT) station (Ichinomiya City, * Shibaharabashi raingauge station (Ishikawa Pref.) Aichi Pref.).

Driftwood accumulated at the Asanogawa Bridge (Kanazawa City) Two houses partially destroyed by a landslide (Nanto City) Inundation in Iga- In Kanazawa City, the flooding of the Asano River left 507 houses flooded cho, Okazaki City above floor level and 1,476 houses flooded below floor level. A total of 55 landslides occurred in Ishikawa and Toyama prefectures, causing damage to In Okazaki City, 620 houses were flooded above floor level, and 705 houses were 20 houses. flooded below floor level. 159