ISSMGE Bulletin: Volume 4, Issue 1

Case History

Geotechnical structure damages during the 2009 Typhoon Morakot

Dr. Wei F. Lee (National Taiwan University of Science and Technology)
Prof. Ikuo Towhata (University of Tokyo)

1. INTRODUCTION

This news reports the geotechnical disasters in Taiwan in August, 2009, that were caused by the extremely heavy rainfalls associated with Typhoon Morakot. Figure 1 shows the path and date of the travel of the typhoon. It is seen herein that the typhoon remained in the Taiwan’s neighborhood from August 7th to 10th. This situation resulted in an extremely heavy accumulation of rainfall. As observed by radar in Fig. 2, the wind brought a lot of cloud and water from the Taiwan Strait towards mountains in the southern part of Taiwan Island. Fig. 3 presents rainfall data during the typhoon period. From August 7th to 10th, the total rainfall in the southern part of Taiwan exceeded 1,500 mm. Furthermore, the 24-hour rainfall on August 8th was more than 700 mm in the same area. A typical rainfall data in the mountain region is the one in Fig. 4, in which the accumulated rainfall reached as much as 2,700 mm in four days.

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Figure 1. Path of Typhoon Morakot

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Figure 2. Vortex of typhoon cloud (radar observation)

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Figure 3. Data of precipitation during typhoon time(Tien-Chien Chen)

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