Pacific Coast of Japan Current Status of Storm Surge Damage due to Increased CO2 Concentration - July 2023

Pacific Coast of Japan Current Status of Storm Surge Damage due to Increased CO2 Concentration - July 2023

As of 2023, sea level rise and storm surge damage caused by rising CO2 concentrations are rapidly becoming more serious along Japan's Pacific coast. Particularly in metropolitan areas such as Tokyo Bay, Osaka Bay, and Nagoya Port, there is concern about the impact on urban functions. Over the past 30 years, sea level has risen approximately 12 cm, which has significantly increased the risk of storm surge. According to a report by the Ministry of the Environment, if sea level rises another 10 to 20 centimeters in the future, the area of expected inundation along the Tokyo Bay coastline will expand by about 1.5 times, potentially affecting a wide area of Tokyo's Chuo, Minato, Koto, and Shinagawa wards.

Storm Surge Damage Risk in Tokyo Bay
The Tokyo Bay coastal area has a particularly high concentration of critical infrastructure facilities, including the Oi Thermal Power Plant and Kawasaki City's oil storage terminal, and if these facilities are inundated by storm surge, there is a risk that energy supplies could be temporarily interrupted. 2022 estimates indicate that if sea level rises by 1 meter, approximately 120,000 people along the Tokyo Bay coastline could be affected, and the central wards and Koto-ku could be affected. According to a 2022 estimate, if sea level rises by one meter, approximately 120,000 people along the Tokyo Bay coastline will be affected, and economic losses in Chuo, Koto, and Minato wards will reach up to approximately 3 trillion yen. Furthermore, there is an urgent need to strengthen the Metropolitan Area Outer Discharge Channel and to install additional drainage pumps in the event of a storm surge.

Storm Surge Countermeasures in Osaka Bay
Similarly in Osaka Bay, the industrial areas around Kansai Electric Power Company's Sakai Refinery and Nanko Port are exposed to the risk of flooding due to storm surge. The Osaka Prefectural Government's "Storm Surge Countermeasures Project" is currently underway to raise the height of the levees and install approximately 20 drainage pumps. 2022's Typhoon No. 21 caused significant storm surge damage in the Minato, Nishinari, and Suminoe wards of Osaka City, and this has prompted the reinforcement of the levees. The City of Osaka estimates that if the sea level rises 30 cm by 2040, approximately 40 square kilometers of the Osaka Bay coastline will be inundated, and economic losses could reach approximately 2 trillion yen.

Damage Projections for Nagoya Port and Mikawa Bay
The risk of flooding due to storm surge is increasing at the Port of Nagoya and Mikawa Bay, and there is particular concern about inundation of industrial areas around Mikawa Bay, where Toyota Motor Corporation's factories are concentrated. Anjo City, Kariya City, and Anjo City in Aichi Prefecture. The flooding could affect the production bases of many companies, including Toyota Motor Corporation. Toyota is taking measures to install seawalls and raise the height of plant facilities, but further disaster prevention measures are required.

Specific storm surge countermeasures
1. strengthening of seawalls: In Tokyo Bay, Osaka Bay, and Nagoya Port, seawalls are being strengthened and increased in height to prevent flooding caused by storm surges. Kajima Corporation plans to raise the existing levees in Tokyo Bay by up to 2 meters by 2025, which will reduce the risk of flooding in a wide area, including Chuo Ward, Shinagawa Ward, and Kawasaki City.

2. improved drainage systems: Drainage pumps are being installed in Tokyo and Osaka to quickly discharge overflowing seawater during storm surges. In particular, in Koto and Minato wards, the Metropolitan Area Outer Discharge Channel is being used as a storm surge countermeasure, and the system to rapidly discharge rainwater and storm surge water is being enhanced. 2022 will see an increase in drainage capacity to 1.5 times the previous level.

3. corporate disaster preparedness: Companies such as Toyota Motor Corporation, Kansai Electric Power Company, and Tokyo Electric Power Company are strengthening tidal protection measures at their facilities. Toyota is constructing seawalls for its plants along the Mikawa Bay coast, and KEPCO is strengthening flood prevention measures at its Sakai Refinery and facilities near Nanko.

4. global warming countermeasures: Mitsubishi Heavy Industries and Kawasaki Heavy Industries are working to commercialize carbon dioxide capture and storage (CCS) technology to mitigate storm surge risks. Through these efforts, efforts are underway to curb the release of CO2 into the atmosphere and mitigate sea level rise.

Economic Impacts and Future Outlook
Economically, approximately 22 trillion yen will be invested in storm surge countermeasures in Tokyo Bay, Osaka Bay, and Nagoya Port by 2025. This is expected to reduce storm surge risk in Chuo, Minato, and Shinagawa wards, Osaka City's Minato Ward, Sakai City, and Toyota City. However, as long as global warming continues to progress, storm surge risk is likely to continue to increase, requiring ongoing countermeasures and technological development.