French – Japanese – Dutch workshop on impacts of climate change on hydrology Adaptation Strategy for Climate Change in Japan July 15, 2008 Toshio Okazumi Director for International Water Management Coordination Ministry of Land, Infrastructure, Transport and Tourism Government of Japan 1. Present conditions Japan is vulnerable to climate change. in Japan Kinki Region Kanto Region A y S a h Ikebukuro s i e n Station R n Ueno a i k v a Station S e r Kanzaki River K u Kameido R an m i da v Amagasaki Ri i Station ved r e Station Shin-Osaka Station a r Tokyo Shinjuku R Kinsicyo Old Edo River Old Edo Station i Station v Station e r Ara River Shibuya Osaka Station Neya River Shibu Yodo River Station ya Ri M ver Osaka Castle e Hirano gu ro Tennouji Station River R Toneiv River er Elevation Elevation About 50% of population 3m – 4m and about 75% of 3m – 4m 1m – 3m 1m – 3m 0m – 1m property on about 10% of 0m – 1m -1m – 0m -1m – 0m -1m – -1m – Water Area land lower than water Water Area levels in rivers during flooding 1. Present conditions Japan, France and the Netherlands in Japan１．我が国の現状 関東地方 Japan France The Netherlands ・Area：378,000km2 ・Area：547,000km2 ・Area：42,000km2 ・Many short steep rivers. ・Almost nation land is Gently ・Rhine River, Maas River, Schelde Geographical characteristics ・Sediment problems because of rolling plain and hill River as mild slope international poor soil ・South Pyrenees and East Alps are river ・Flood plain area is located by precipitous mountains ・Delta and low area alluvial fan and riverside Name of River Tone River Seine River Rhine River Profile of Basin Area About 17,000km2 About 78,000km2 About 185,000km2 represent ative length of river 322km 776km 1,320km river Average bed slope About 1/175 About 1/1,650 About 1/2,600 largest flow discharge 17,000m3/s(1947) 2,400m3/s (1910) 13,000m3/s (1926) annual mean rainfall 1,718mm About 1,000mm About 800mm Climate 100 year daily precipitation characteristics 376mm（Tokyo） About 79.4mm (Montsouris) 80mm（de Valdo） 100 year hourly precipitation 94mm（Tokyo） About 47.4mm (Montsouris) 40mm（ de Valdo ） 2. Outline of the IPPC Mechanism of global warming and climate change (impacts on water-related disasters) AR4 Report Large volumes of greenhouse gas emissions cause CO2 concentration in the air to rise and increase heat absorption, resulting in temperature rise. Thus, global warming occurs. Melting of glaciers, ice caps and Thermal expansion Change in Change in snow ice sheets of sea water evapotranspiration accumulation condition Sea level rise (Maximum rise: 59 cm) More intense typhoons Increase of More frequent heavy Earlier snow melt precipitation by a rains and droughts and reduction of factor of 1.1 to 1.3* discharge Change in water use Increase of river flow rate pattern MoreMore frequentfrequent highhigh tidestides andand coastalcoastal MoreMore frequentfrequent MoreMore seriousserious debrisdebris flowflow HigherHigher riskrisk ofof droughtdrought erosionserosions floodsfloods 2. Outline of the IPPC Rises of temperature and sea level AR4 Report -Temperature is expected to rise by about 0.2℃ per decade in the next 20 years. -Global average surface temperature is expected to rise by 1.8 to 4.0℃ in 100 years' time from now. -Global average sea level is expected to rise by 18 to 59 cm in 100 years' time from now. -Global warming and sea level rise will continue over several centuries even if green-house gas emissions are controlled. ・Average temperature ・Average sea level 700 ) 600 ℃ 500 Case where CO2 concentration in 2000 水 will remain unchanged 位 400 Peak 20th century Rise of 4.0℃ 変 化 300 590mm ( 200 m m 100 Rise of 1.8℃ ) 0 -100 Change in sea level (mm) level in sea Change -200 1860 1880 1900 1920 1940 1960 1980 2000 2020 2040 2060 2080 2100 Source: Data prepared by the River Bureau based on the IPCC AR4 WG1 Report Rise of global average surface temperature ( surface temperature average Rise of global ・Rises of average temperature and sea level at the end of the 21st century Year A1: High growth oriented society Society achieving both Society achieving high A1Fl: Dependent on fossil energy sources global environmental economic growth A1T: Dependent on non-fossil energy sources protection and dependent on fossil A1B: Emphasis on the balance among various economic development energy sources energy sources A2: Multipolarized society About 1.8℃ About 4.0℃ B1: Sustainable growth oriented society Temperature rise (from 1.1℃ to 2.9℃) (from 2.4℃ to 6.4℃) B2: Emphasis on regional initiatives Source: Sea level rise Sea level rise ２６～５９ｃｍ IPCC AR4 WG1 (Working Group 1) Summary for Policymakers (Japan Meteorological Agency) -Solid lines indicate rises of global average surface temperature in each scenario identified using multiple models. -Shaded areas indicate the range of standard deviations of average annual temperature for each model. Source: IPCC AR4 WG1 Report 3. Impacts of Resolution of climate change prediction models heavy rains Resolution気候変動の予測を行うモデル of climate change prediction models has been improved year by year. の解像度は年々進歩 IPCCＩＰＣＣ１次報告書（１９９０） First Assessment Report (1990): Horizontal resolution of about 500水平解像度 km 約500km IPCCＩＰＣＣ２次報告書（１９９６） Second Assessment Report (1996): Horizontal resolution of about 250水平解像度 km 約250km IPCCＩＰＣＣ３次報告書（２００１） Third Assessment Report (2001): Horizontal resolution of about 180水平解像度 km 約180km IPCCＩＰＣＣ４次報告書（２００７） Fourth Assessment Report (2007): Horizontal resolution of about 110水平解像度 km 約110km GCM20GCM20 and RCM20:、RCM20 Horizontal ※メッシュの大きさを表現したもので、実際のメッシュ箇所とは関係ないMesh sizes are simply indicated regardless of actual mesh locations. resolution水平解像度 of about 20 約 km20km Prediction model in this河川局作成 study 3. Impacts of Estimation of increased rainfall in region heavy rains Future rainfall amounts were projected as a median value in each region of Average rainfall in 2080-2099 period Average rainfall in 1979-1998 period ② The above equation was obtained based on the maximum daily precipitation in the year ① at each survey point identified in GCM20 (A1B scenario). ① Hokkaido 1.24 ④ ② Tohoku 1.22 ③ ⑧ ③ Kanto 1.11 ⑤ ④ Hokuriku 1.14 ⑨ ⑥ ⑤ Chubu 1.06 ⑦ ⑥ Kinki 1.07 ⑩ Legend ⑦ Southern Kii 1.13 ⑪ 1.20～1.25 ⑧ San-in 1.11 1.15～1.20 ⑨ Setouchi 1.10 1.10～1.15 ⑩ Southern Shikoku 1.11 1.05～1.10 ⑪ Kyushu 1.07 1.00～1.05 3. Impacts of Declining return period by increasing rainfall heavy rains Return period of flood is declining by increasing rainfall in the future. Therefore declining future flood safety level is estimated. 【Image of declining return period at certain area】 Maximum daily rainfall × 1.2 return period future current 1/100 current data projected data 1/ 50 Rainfall probability sheets rainfall r 3. Impacts of Declining the degree of safety level heavy rains Impact for flood safety level by changing rainfall after 100 years Declining the degree of safety against flood 1/200 （CurrentTarget ） 1/150（CurrentTarget） 1/100（CurrentTarget ） （annual exceedance probability） （ by increasing future rainfall Region Future flood safety level exceedanceannual probability 200 Number of Number of Number of river system river system river system 175 Hokkaido － － 1/40 ～ 1/70 2 1/25 ～ 1/50 8 level safety Flood 150 Tohoku － － 1/22 ～ 1/55 5 1/27 ～ 1/40 5 Kanto 1/90 ～ 1/120 3 1/60 ～ 1/75 2 1/50 1 125 Hokuriku － － 1/50 ～ 1/90 5 1/40 ～ 1/46 4 100 Cyubu 1/90 ～ 1/145 2 1/80 ～ 1/99 4 1/60 ～ 1/70 3 75 Kinki 1/120 1 － － － － 50 Southern Kii － － 1/57 1 1/30 1 25 ） Saninn － － 1/83 1 1/39 ～ 1/63 5 0 Current Target Hokuriku Shikoku Southern Kyuusyuu Kanto Hokkaido Tohoku Setouchi Cyubu Saninn Kinki 計 北 東 関 北 中 近 Southern Kii 紀 山 瀬 四 九 Setouchi 1/100 1 1/82 ～ 1/86 3 1/44 ～ 1/65 3 画 海 北 東 陸 部 畿 伊 陰 戸 国 州 Southern Shikoku － － 1/56 1 1/41 ～ 1/51 3 道 ③ ② ① 南 内 南 ① ③ Kyusyu － － 1/90～1/100 4 1/60～1/90 14 ② 部 ① 部 All Japan 1/90 ～ 1/145 7 1/22 ～ 1/100 28 1/25 ～ 1/90 47 ① （ annual exceedanceannual probability （ 150 exceedanceannual probability 100 Flood safety level safety Flood 125 level safety Flood 75 100 75 50 50 25 25 ） Kyuusyuu Kanto Shikoku Southern Hokuriku Current Target Hokkaido Tohoku Setouchi Cyubu Kinki 0 計 北 東 関 北 中 近 紀 山 瀬 四 九 0 計 北 東 関 北 中 近 Southern Kii 紀 Saninn 山 瀬 四 九 Hokuriku Shikoku Southern Kyuusyuu Kanto Cyubu Hokkaido Tohoku Saninn Kinki Setouchi Current Target Southern Kii ） 画 海 北 東 陸 部 畿 伊 陰 戸 国 州 画 海 北 東 陸 部 畿 伊 陰 戸 国 州 道 ⑤ ② ⑤ ④ 南 ① 内 南 ④ 道 ⑤ ① ④ ③ 南 ⑤ 内 南 ⑭ ① ③ ② ② 部 ③ 部 ⑧ 部 ⑤ ③ 部 ④ ⑤ ① ③ ⑤ ③ ① ④ ① ③ ① ① ⑧ ③ ⑤ ⑭ ② ① ④ ① ※ Circled number is number of calculated river system 3. Impacts of Changes of peak runoff by future rainfall heavy rains Estimations of future rainfall are about ×1.0 ～×1.5 compare to current rainfall. Peak runoff will be estimated about ×1.0 ～×1.7 compare to current rainfall in 9 major rivers. 計画降雨量の増加と基本高水のピーク流量の変化 Design Rainfall ×1.0 ×1.1 ×1.2 ×1.3 ×1.5 Ishikari石狩川 Riv. Design Level Basin Area Peak Runoff of Design Flood (Hokkaido)(北海道） １／１５０ 12,697ｋｍ2 18,000 m3／s 20,500 23,000 25,600 30,700 北上川 Kitakami Riv. １／１５０ ｋｍ2 3／ (Tohoku)（東北） 7,070 13,600 m s 15,700 17,800 19,900 24,000 Tone利根川 Riv. About 21,000 m3／s １／２００ 5,114ｋｍ2 23,600 25,900 27,900 31,800 (Kanto)（関東） (Calculated by 1/200) 黒部川 Kurobe Riv.