Adaptation Strategy for Climate Change in Japan - Toward Water-disaster Adaptive society - September 22, 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 and issues 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 2008 Floods in Japan and issues 2008.7.28 Floods in Hyogo Pref. 2008.8.29 Floods in Aichi Pref. Rapid water level rise of Amount rainfall per hour 雨量 Amount rainfall per hour 134cm in 10 minutes 160 largest-ever 140 120 amount rainfall 100 per hour 80 60 40 (146mm/h) 20 0 15 16 17 18 19 20 21 22 23 24 1 2 3 4 5 6 7 8 9 10 Break Point 1. Present conditions Increase of torrential rain and issues Annual total of hourly rainfall instances 1. Number of instances of 50 mm or more rain in an hour (from approx. 1,300 AMeDAS locations across Japan) 500 (instances/year) 400 300 200 1996~2005 100 1976~1985 1986~1995 Average 288 instances Average 209209 instances Average 234234 instances 288 01976 ‘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 2. Number of instances of 100 mm or more rain in an hour 10 (instances/year) 1976~1985 1986~1995 1996~2005 Average 4.74.7 instances Average 22.22 instances Average 2.22.2 instances 5 0 1976 ‘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 Data from the materials prepared by the Meteorological Agency 2. Impacts of climate Mechanism of global warming and climate change change 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. Impacts of climate Estimation of increased rainfall in region change 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 2. Impacts of climate Impacts of precipitation 100 years from now on safety against flood change Precipitation 100 years from now is projected to be about 1.1 to 1.3 times the present level. The highest projection may be 1.5 times. Impacts of precipitation 100 years from now on safety against flood 1/1000 最大 Highest 最小 Lowest 1/200 1/150 1/100 1/100 1/100 1/100 1/80 1/60 1/60 1/55 1/35 1/70 1/35 1/35 1/45 1/23 1/40 1/15 1/23 治水安全度 1/22 1/12 Safety 1/10 1/12 1/10 1/6 1 現計画Present plan 1.1倍1.1 times 1.2倍1.2 times 1.3倍1.3 times 1.5倍1.5 times 現計画Present plan 1.1倍1.1 times 1.2倍1.2 times 1.3倍1.3 times 1.5倍1.5 times 現計画Present plan 1.1倍1.1 times 1.2倍1.2 times 1.3倍1.3 times 1.5倍1.5 times Safety in present plan: 1/100 Safety in present plan: 1/150 Safety in present plan: 1/200 The safety designated in the present plan would substantially deteriorate based on the assumption of projected precipitation 100 years from now. More frequent inundation and flooding 2. Impacts of climate Changes of peak runoff by future rainfall change Estimations of future rainfall are about ×1.1 ～×1.5 compare to current rainfall. Peak runoff will be estimated about ×1.1 ～×1.7 compare to current peak runoff 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. ｋｍ2 7,200 m3／s (Hokuriku)（北陸） １／１００ 667 8,100 8,900 9,700 11,300 Izumo雲出川 Riv. 2 3 (Cyubu)（中部） １／１００ 541ｋｍ 8,000 m ／s 9,000 9,900 10,900 12,800 紀の川 Kinokawa Riv. 2 3／ (Kinki)（近畿） １／１５０ 1,574ｋｍ 16,000 m s 17,600 19,700 21,600 25,400 Oota太田川 Riv. (Cyugoku)（中国） １／２００ 1,505ｋｍ2 12,000 m3／s 13,100 14,700 16,300 19,400 Naga那賀川 Riv. (Shikoku)（四国） １／１００ 765ｋｍ2 11,200 m3／s 12,800 14,500 16,100 19,300 Kase嘉瀬川 Riv. 2 3 (Kyusyu)（九州） １／１００ 225.5ｋｍ 3,400 m ／s 3,800 4,100 4,500 5,300 0% 20% 40% 60% 80% 100% 120% 140% 160% 180% 2. Impacts of climate Frequent and more serious droughts: Deterioration of safety against droughts change ■There has been a smaller rainfall amount in recent years and the range of variation has been lower than in the late 1940s through the late 1960s when dams and other facilities were constructed. ■As a result, stable water supply using dams has been decreasing. Example in the Kiso River system ◇In recent years (in 1979 through 1998): Reduction of water supply below the design level by about 40% ◇Worst drought in recent years (1994): Reduction of water supply below the design level by about 70% Annual 年降水量precipitation (㎜/年)(mm/year) Trend Average Dam and other facilities 3,000 2,500 Reduction by about 40% Reduction by about 70% 2,000 1,500 ▲Year of drought 1,000 Design water supply Possible stable supply Worst drought in recent years 1946S211951 S261956 S311961 S361966 S41 S461971 S511976 1981 S561986 S611991 H31996 H82001 H13 (February 20) (1994) 2. Impacts of climate More frequent and serious droughts change Comparison between present conditions(1979 to 1998) Comparison between and future rainfall(2080 to 2099) in Class A river present water volume and predicted water volume after 100 years shows decrease in most area in March - June Water volume means the sum of snowfall and rainfall Reduction of river flow in the reaching to the earth’s surface. periods requiring irrigation water, e.g. during the surface soil Legend puddling in paddy fields, may be Future water volume/present water deteriorated to water use for volume ≧ 1.4 1.2 ≦ Future water volume/present rice farming. water volume < 1.4 1.0 ≦ Future water volume/present water volume < 1.2 0.8 ≦ Future water volume/present water volume < 1.0 Future water volume/present water volume < 0.8 Spring (March through June) Source: Water Resources in Japan 2007, Land and Water Bureau, Ministry of Land, Infrastructure and Transport 2. Impacts of climate Frequent and more serious droughts change In the upper Tone River, snow cover With global warming, is likely to decrease considerably. (i) earlier snow melt and (ii) reduction of snowfall That will accompany the reduction of induce changes in river flow rate, and river flow rate in the snow melt (iii) earlier surface soil puddling in paddy fields is season or in early spring. expected to cause the annual water demand pattern to change and to have serious impacts on water use. ChangeChange inin snowsnow covercover inin 100100 years'years' timetime duedue toto furtherfurther globalglobal warmingwarming (Fujiwara)(Fujiwara) (ii) Reduction of river (i) Earlier discharge due to earlier flow rate due to snow melt 300 reduction of the amount Average平均 of snowfall 250 Future将来 200 Reduction of river flow during the 積 surface soil puddling in paddy fields 雪 150 深 cm） 100 /sec) 3 Snow cover (cm) cover Snow 50 Future将来 Present現況 0 10月1日October 1 November 11月 1日 1 December 12月1日 1 January 1月1日 1 February 2月1日 1 March 3月 1日1 April 4月1日 1 5月1日May 1 *Prepared by Water Resources Department, Water and Land Bureau, Ministry of River flow (m Land, Infrastructure and Transport based on Regional Climatic Model (RCM) 20, a global warming prediction model, developed by Japan Meteorological Agency.