Special Issue on Meteorological Disasters and Water Disasters in Urban Areas
Nobuo Shuto*, Syunsuke Ikeda**, Shinji Egashira
*ARISH, Nihon University, 6F Ichigaya Tokyu Building, 2-1 Kudan-kita 4-chome, Chiyoda-ku, Tokyo 102-0073, Japan
**Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8552, Japan
Immediately after World War II, economic and human losses due to water disasters were enormous in Japan. In the years of 1947 and 1953, for example, economic loss reach 10% of personal income, and the number of lives lost in the 1959 Isewan Typhoon exceeded 5,000. The Japanese government then implemented successive 5-year flood control plans that dramatically reduced such disasters. Economic loss by flooding now is on the order of 0.2% of personal income, and fewer than 100 lives are lost per year. The situation has begun changing in the last decade, however, ostensibly due to global warming and local climatic change such as the heat island phenomenon. The most typical change is the increase in heavy precipitation. Meteorologists sometimes call 1997 the turning point in climate change. The year 1998 was one of extreme heavy rain in Japan, with downpours exceeding 100 mm/h occurring 10 times and those of 50 mm/h almost 440 times. The record for 50 mm/h was broken in 2004, when some 470 such downpours occurred. Another marked change has been the increase in the fluctuation of precipitation, suggesting that drought may follow floods as a typical pattern portending major water disasters in the future. Lifestyle changes are another factor inducing water disaster. Increased urban populations inherently induce concentrated land use, paving of land surfaces, hazardous living conditions, etc. Frequent urban flooding and high underground use in Japan increases the danger for inundations. Wind disasters are also increasing. In September 2006, a tornado in Nobeoka, Kyushu, killed 3 people. In November 2006, another tornado struck Saroma, Hokkaido, killing 9 workers when a construction company’s meeting room was destroyed. Polluted material transported long distances by wind is a big problem in Asia. Smoke from forest fires and chemical pollutants increasingly endanger people outside of the countries of origin, spreading throughout the continent and to islands beyond. This issue reviews recent meteorological and hydrographic disasters in urban areas that threaten to become major problems in the 21st Century.