Sediment Disasters and Sabo Works in Japan

Hiroshi Ikeya
Sabo Technology Research Institute, Sabo Technical Center, Tokyo
ikeya@stc.or.jp

In Japan, 70% of this small national land is covered with mountains and the area where human can live is limited, also 125 million people lives in the Japanese islands, more and more places have been put at risk of the sediment-related disaster (so called sediment disaster) through the development of piedmonts and hill zones for residence. Therefore the Japanese people cannot help living such places where sediment movement, attend topographical variation, occurs easily because of topographical, geological, meteorological conditions. So sediment disasters occur frequently. Then I will introduce examples of these sediment disasters and prevention and mitigation measures, that is called Sabo Works, against them, based on the volcanic eruption of Mt. Unzen since 1991 and its countermeasures.