Aerial view of Kansai International Airport on 4 September 2018, after Typhoon Jebi's storm surge inundated one runway and flooded Terminal 1. Photo: Kentaro Ikushima / Mainichi Newspaper / AP

Dr. Jeff Masters
21 September 2018

(Weather Underground) –  In a stunning demonstration of the destructive potential of typhoon storm surge—and the human propensity to under-engineer infrastructure designed to withstand the worst nature has to offer—Japan’s third busiest airport, Kansai International Airport in Osaka Bay, was inundated by Category 2 Typhoon Jebi’s storm surge on 4 September 2018. The surge flooded one runway, closing it for ten days, and damaged electrical facilities in one of the airport’s two terminals, forcing its closure for seventeen days. The airport was fully open today for the first time since the disaster. The last time a typhoon of similar size and strength hit Osaka Bay was in 1961: Typhoon Nancy, which made landfall as a Category 2 storm with 100 mph winds.

According to storm surge expert Dr. Nobuhito Mori of Kyoto University, Jebi brought the highest storm surge on record to Osaka Bay: 2.8 meters (9.2 feet). The peak surge occurred near the time of high tide, bringing a total storm tide of 3.29 meters (10.8 feet), breaking the previous record of 2.93 meters (9.6 feet). A damage survey released on September 21 found that even higher water levels of over 5 meters (16.4 feet) occurred in some portions of Osaka Harbor, when the influence of the waves on top of the surge was included (see Google Earth .kml file here).

Typhoon Jebi—a former Category 5 super typhoon—struck Japan’s main island of Honshu near Osaka near noon local time on September 4. The Joint Typhoon Warning center rated Jebi as a Category 1 storm with sustained 1-minute winds of 85 mph just before landfall, but the Japan Meteorological Agency (JMA) rated Jebi as being much stronger: 100 mph sustained 10-minute winds, equivalent to a high-end Category 2 storm. Winds measured at land stations supported at least a Category 2 storm, and a JMA spokesperson said Jebi was the strongest typhoon to strike Honshu in 25 years.

Jebi took a worst-case track for generating a record storm surge in Osaka Bay: the eye passed along the west side of the bay, and the powerful right-front eyewall winds pushed a large storm surge into the bay’s shallow waters. Kansai International Airport, located on the east side of the bay, likely received a storm surge of about 1.5 meters (4.9 feet), with the high tide bringing an additional 0.5 meters of water, for a total storm tide of about 2 meters (6.6 feet), according to a storm surge simulation run by Dr. Mori. It’s possible the surge was higher than that, as the post-storm damage survey found water levels up to 3.03 meters (10 feet) above normal on the mainland where the connecting bridge to the airport ends. Breaking waves on top of the surge (not included in Dr. Mori's model) probably contributed another 0.5 meters of surge. The airport, which lies on an artificial island constructed at a cost of $20 billion, two miles from shore, was designed to handle a storm surge of up to 3.7 meters (12 feet). [more]

Japan’s Typhoon Jebi Demonstrates the Vulnerability of Airports to Storm Surge



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