Debris flow occurrences are recorded all over the world. Among the countries most affected by debris flows, there are few that stand out, namely Venezuela, Japan, China, Thailand, Nepal, Indonesia, Philippines, Italy, Switzerland, France, Germany, Portugal, Slovenia, Colombia, the United States of America, Peru and Australia.
In last 30 years, the most relevant debris flows events were:
- Colombia, Armero city on 13th November 1985
- Italy, Sarno on 5th and 6th May 1998
- Venezuela, state of Vargas on 15th and 16th December 1999
- Slovenia, Log pod Mangartom on 17th November 2000
- Thailand, Nam Ko village, on 11th August 2001
- Japan, Minamata city on 20th July 2003
- Philippines, Guinsaugon village on 17th February 2006
- Brazil, Rio de Janeiro state, 11th and 12th January 2011
According to Takahashi (2007), Japan is one of the most overwhelmed countries in the world by debris flow events. This phenomenon directly resulted in more than 1 400 human life losses, between 1967 and 1997. Takahashi refers that debris flow occurrences in Japan might be considered as inevitable under country natural and social conditions. Thus, Japanese scientific community had been extremely active and performed several studies and reports in order to increase debris flow phenomenon knowledge as well as to evaluate the most effective mitigation measures.
Between 1996 and 2006, the relevant debris flow occurrences in Japan were:
- Gamaharazawa in 1996 – 14 casualties
- Harihara River in 1997 – 24 casualties
- Hiroshima in 1999 - 24 casualties
- Minamata in 2003 – 19 casualties
In the European Alps are also frequently registered the occurrence of several mass movements, namely debris flows. According to Wendeler, et al. (2007), 4 to 6 annual events are expected in the Swiss Alps. However, alpine debris flows usually occur in regions without any significant social and economical impacts. Nevertheless, there are several Alpine villages, settled nearby risk areas where debris flows often occur.
References:
Takahashi, T., 2007. Debris Flow: Mechanics, Prediction and Countermeasures.Taylor & Francis.
Wendeler, C. et al., 2007. Field measurements and numerical modelling of flexible debris flow barriers.