1

TopicA survey of container drift damage
in Mikawa Port caused by the storm
surge of Typhoon No. 18Photo

KUMAGAI Kentaro, Senior Researcher, Coastal Disaster Prevention Division, Coastal and Marine Department(Keywords) Typhoon No. 18, storm surge, container, drift, damage survey
1. Overview of the damage survey
On October 8, 2009, Typhoon No. 18 came ashore near
the Chita Peninsula. The surge associated with thetyphoon caused flooding and scattered a large number ofcontainers on the wharves of Mikawa Port (Photo 1).
In cooperation with the Chubu Regional Bureau’s Portand Airport Department and the Port and Airport
Research Institute, the author surveyed damage to theJinno-Nishi Wharf in Mikawa Port and its vicinity on
October 9, the day following the typhoon’s landfall.
The main components of the survey were 1) a survey ofthe conditions of flooding
caused by the storm surge,2) interviews on theactual circumstances ofcontainer drift, and 3) asurvey of damage to theport facilities.
2. Survey results

Photo 1: Scattered containers(provided by Japan Coast Guard)(1) Damage caused by the storm surge: Tide observation
records of the Chubu Regional Bureau showed a highest
tide level of D.L.+4.40 meters at 6:20. It should be
noted that the tide observation station is locatedapproximately one kilometer from the pier. The groundheight of the wharf’s No. 8 pier is D.L.+4.11 to 4.16
meters, and there is a gentle upward slope inland fromthere that reaches D.L.+4.34 meters at its highest point.
Behind this is a gentle downward slope to around D.L.+4
meters and then a relatively flat area. Accordingly, it isthought that the flood depth of the wharf, minus theeffects of the waves and wind, was between 0.1 and 0.4
meters. In some locations, this is equivalent to a flood
depth at which even double-stacked containers wouldfloat (see reference*). Grass that had drifted due to the
influence of the waves and wind was entangled in thefence surrounding the wharf (ground height of D.L.+4meters) to a height of 0.7 to 0.9 meters.
(2) Actual conditions of container drift: According to theAichi Prefecture’s Mikawa Port Office, which has
jurisdiction over the port, 136 containers out of 887 stored
on the wharf moved significantly. The maximum
straight-line distance of movement was approximately
250 meters. Most of the containers were stopped by asteel fence or nets that surround the wharf. The resultsof an interview with a witness are shown in Table 1.
Marks indicating places where containers had been

dragged were found in several areas on the pavement near
the highest point in the No. 8 pier yard (Photo 2). Thus,
it was found that some of the containers did notcompletely float but were rather dragged.
Table 1: Interview results
Time
5:45
6:20
7:00
7:30

Witnessed conditions
Seawater was confirmed overflowing from the No. 8 pier.
Container drift was confirmed. Containers did not startmoving all at once, but little-by-little. They bobbed likeboats made of bamboo leaves as they floated. Some
containers were carried away while still stacked.
The containers stopped moving.
The water was withdrawn completely from the top of thewharf at this time.

(3) Damage to wharf facilities: The posts of the steel
fence surrounding the wharf were deformed due to theimpacts of the containers. In one example, a post
measuring 6 cm in diameter was deformed in two
locations at heights of 0.5 and 0.9 meters above theground (Photo 3). There were no instances where theentire fence was knocked down.

Photo 2; Drag marks

Photo 3: Fence post

3. Conclusion
While referring to the results of the survey, the author
intends to conduct a numerical analysis of cargo thatdrifted from the wharf and study appropriate cargo
management measures needed for countermeasuresagainst drift damage. The author wishes to express hisgratitude to Mr. Yoji Hirai, head of the Chubu Regional
Bureau’s Mikawa Port Office, and others for theircooperation in this survey.
*Generally, there is a raised height of approximately 0.15 metersthat serves as a tunnel recess (depression for trailer loading), etc.
Considering this, it is thought that empty 40-foot containers
would float in floodwater having a depth of 0.28 meters whensingle stacked and 0.39 meters when double stacked.