COUNTERMEASURES AGAINST STORM SURGE May 24th, 2006 Susumu Murata Coastal Development Institute of Technology, Japan

Major Typhoon Disasters in Japan Kitty （ 1949 ） Ise-wan （ 1959 ） Ruth （ 1951 ） Jane （ 1950 ） 2 nd Muroto （ 1961 ） Muroto （ 1934 ） Kano-gawa （ 1958 ） No. 13 （ 1953 ） No. 26 （ 1966 ） No. 18 （ 1991 ） No. 18 （ 2004 ） No. 23 （ 2004 ） No. 16 （ 2004 ）

Damage by Typhoon Ise-wan (Sep. 26 th, 1959) 【 Damage 】 ●The Number of Victims Dead or Missing ５，０９ ８ ○The Number of Buildings Destroyed Completely or Half １５１, ９７ ３ Levee breaches and inundation disasters Timbers and logs washed away to apartment houses

Tokyo Bay （ Yokohama ～ Chiba ） Ise Bay （ Kawagoe ～ Tokai ） Osaka Bay （ Ashiya ～ Osaka ） Below High Water Level Tokyo Bay Ise Bay Osaka Bay Total Area （ km 2 ） Population (thousand) 1, ,3804,040 ■ ： Below T.P.±0m ■ ： Below High Water Level ■ ： Below High High Water Level Storm Surge High Risk Areas in 3 Major Bay Regions

Tokyo Bay （ Tokyo Port ） Ise Bay （ Nagoya Port ） Osaka Bay （ Osaka Port ） Force Ise-wan Typhoon （ Sep ） Projected Storm Surge Height Ｔ．Ｐ． ＋３．０～４．０ m Ｔ．Ｐ． ＋４．５ m Ｔ．Ｐ． ＋３．９ m Storm Surge Deviation ２．０～３．０ m ３．５ m ３．０ m HWL Ｔ．Ｐ． ＋１．０ m Ｔ．Ｐ． ＋０．９ m CourseWorst ScenarioIse-wan TyphoonMuroto Typhoon Conditions of Seawall Design High Water Level (HWL) Wave Wash Allowance Projected Seawall Height Projected Storm Surge Height Seabed Deviation from HWL by Storm Surge How to Determine Height of Seawall against Storm Surge Projected Seawall Height ＝ HWL ＋ Storm Surge Deviation ＋ Wave Wash ＋ Allowance Wave Storm Surge

【 Sufficiency of Seawall Height 】 ◎ Once seawalls are breached by a disaster beyond projection, serious damage will occur in these areas. ◎ Steady Development of Facility & Enhancement of Credibility of Facility ◎ Promotion of Damage Minimization Measures Preparing for Serious Flooding Situation ◎ Aging of facilities protecting areas lying at sea level is progressing. ◎ 65% of seawalls in Japan have sufficient height. ◎ 93% of seawalls in 3 major bay areas have sufficient height. 【 Many facilities were constructed more than 40 years ago in 3 major bay areas. 】 ～ ～ ～ ～ ～ Unknown Sufficient Temporarily Sufficient Insufficient Unknown 22 ％ 2959km 5 ％ 657km 9 ％ 1176km All Japan 93 ％ 285km 4 ％ 13km 3 ％ 8km 65 ％ 9000km 全 327km 327km Problem with Storm Surge in Areas Lying below Sea Level 3 Major Bay Areas

Recommendation by Panel on Storm Surge Control Measures in Areas below Sea Level (January 2006) Ⅰ Basic aspects of storm surge control measures in areas below sea level ・ Need of damage minimization against large-scale inundation ・ Future Storm Surge Control Measures in Areas below Sea Level Ⅱ Specific measures to be taken 1.Measures to fully prevent inundation through the existing storm surge defense plans ⅰ Steadily constructing storm surge defense facilities ⅱ Securing the reliability of disaster defense facilities ⅲ Enhancing normal management system 2.Damage minimization measures against large-scale inundation ⅰ Minimizing inundated areas ⅱ Shifting to a way of living free from inundation damage ⅲ Ensuring quick and safe evacuation and relief ⅳ Keeping facilities operational for rapid relief, restoration and rehabilitation Future Storm Surge Control Measures in Areas below Sea Level

3.Accumulation and dissemination of storm surge defense knowledge 4.Additional challenge to be undertaken to ensure the security against storm surge disasters ⅰ Investigations and studies concerning the evaluation of structural strength of storm surge protection facilities against external forces ⅱ Investigations and studies concerning the evaluation of probability of storm surge as a design external forces ⅲ Investigations and studies concerning the refinement of storm surge protection facilities inspection methods for their efficient maintenance, repair technology and deterioration control measures ⅳ Investigations and studies concerning the development of methods for quickly restoring levees breached by storm surge ⅴ Investigations and studies concerning protection measures against sea level rise due to global warming and land use in coastal areas ⅵ Investigations and studies concerning disaster protection systems (including tax and insurance systems) in coastal areas

Urgency of Large-Scale Earthquake c.f. 【 Encounter Risk in 30 years 】 Killed (Traffic Accident): ０．２％ Injured (Traffic Accident): ２０％ Killed or Injured (Fire): ０． ２％ Encountered (Fire): ２％ 【 Probability of great earthquakes occurring in 30 years 】 Nemuro （Ｍ 7.9 ） 40 ％ Tokachi （Ｍ 8.1 ） 0.5 ％ Sanriku North ( Ｍ 8.0) 7 ％ ( Ｍ 7.1 ～ 7.6) 90 ％ Miyagi （Ｍ 7.5 ） 99 ％ Minami Kanto （Ｍ 6.7 ～ 7.2 ） 70 ％ Taisho Kanto （Ｍ 7.9 ） 0.9 ％ Genroku Kanto （Ｍ 8.1 ） 0 ％ Tokai （Ｍ 8.0 ） 86 ％ Tonankai （Ｍ 8.1 ） 60 ％ Nankai （Ｍ 8.4 ） 50 ％ Sadogashima North （Ｍ 7.8 ） 6 ％ Akita （Ｍ 7.5 ） 3 ％ Hokkaido North West （Ｍ 7.8 ） 0.1 ％ Hyuganada （Ｍ 7.6 ） 10 ％ Sanriku ～ Boso ・ Tsunami （Ｍ 8.2) 20 ％ ・ Rift （Ｍ 8.2 ） 7 ％ Akinada ～ Bungosuido （Ｍ 6.7 ～ 7.4 ） 40 ％ Yonagunijima （Ｍ 7.8 ） 30 ％ Sanriku South( Ｍ 7.7) 70 ～ 80 ％

Enhancement of Reliability of Coastal Protection Facility Development of Coastal Protection Facility ◎ Promotion of Hazard Map Preparation ◎ Systemization of Storm Surge & Tsunami Information Collection & Dissemination ◎ Inspection of Seawall & Flood Gate Condition ◎ Management of Facility Condition including Maintenance & Repair based on Inspection Record ◎ Minimization of Damage to Property as well as Life Protect Life Protect Property Urgent Steady Approach to Storm Surge & Tsunami Disaster Facilitation of Evacuation Non-Facility ApproachFacility Development

① Automation and remote control of gates ② Disaster prevention center ③ Functional upgrade of Seawalls ① Automation and remote control of gates ⑥ Evacuation routes ② Disaster prevention center ⑤ Information transmission facilities ③ Functional upgrade of seawalls Tsunami ! Storm Surge! ④ Hazard map ⑤ Information transmission facilities ⑥ Evacuation routes ④ Hazard map Urgent plan for risk management on tsunami and storm surge disaster