Heavy rain hits western Japan, flooding downtown Osaka
Unstable atmospheric pressure caused by warm and humid winds flowing toward a rain front brought heavy rain to western Japan on Aug. 25, flooding extensive areas including the Umeda district of downtown Osaka, weather officials and police said.
The western Shimane Prefecture city of Masuda had record rainfall of 87 millimeters over an hour on Aug. 25, while Osaka's Chuo Ward saw a record 27.5 millimeters of rain over a 10-minute period on the morning of the same day.
The Hyogo Prefecture city of Nishinomiya, the Kumamoto Prefecture city of Aso and the Yamaguchi Prefecture city of Hagi saw 78, 77 and 76.5 millimeters of rain, respectively, for an hour. Osaka Airport in the Toyonaka area of Osaka Prefecture had 66 millimeters of rain per hour.
Data from a weather radar indicated that about 100 millimeters of rain fell near Tsuwano, Shimane Prefecture, over an hour period, prompting the local meteorological observatory to issue a warning for record-breaking heavy rain over a short-period in the region.
Services on the JR Sanko Line that connects Gotsu, Shimane Prefecture, and Miyoshi, Hiroshima Prefecture, have been suspended since a bridge was washed away near Inbara Station in Shimane Prefecture. There is no prospect that services on the line will be resumed in the foreseeable future.
In big cities in Osaka and Hyogo prefectures, houses, entertainment districts and underground passages around railway stations were flooded. The underground passageway of JR Settsu-Motoyama Station in Higashinada Ward, eastern Kobe, had floods 60 to 70 centimeters deep, and station workers carried some passengers on their shoulders.
Wide areas around Hankyu Railway Umeda Station in Kita Ward, Osaka, including shopping malls, were flooded, forcing many stores to temporarily close down.
The 58-year-old manager of a drugstore in the area, which was flooded above floor level, said, "I had never experienced such a massive flood before."
In Osaka Prefecture, 26 houses in Toyonaka, Suita, Osaka and other cities were flooded above floor level while 202 other structures were submerged below floor level, while more than 70 houses were flooded in the Hyogo Prefecture cities of Nishinomiya, Ashiya, Amagasaki and other areas, local government officials said.
A disaster-prevention expert pointed out that the capacity of drainage facilities at entertainment districts in urban areas, which can typically respond to heavy rain amounting to 50 to 60 millimeters per hour, is insufficient in countering torrential rains.
"The number of cases of localized torrential rain over a short period has been increasing. Even if shopping districts are equipped with draining systems, they cannot sufficiently drain water from torrential rain during a short period if the places are situated in lowland areas, occasionally causing a flood," said professor Keiichi Toda of Kyoto University.
August 26, 2013(Mainichi Japan)