Tham khảo tài liệu 'earth sciences part 3', khoa học tự nhiên, công nghệ sinh học phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 70 Earth Sciences Wandersee . Mintzes . Novak . 1994. Research on alternative conceptions in science. In D. Gabel Ed. Handbook of research on science teaching and learning Chapter 5 pp. 177-210 . New York Macmillan. 4 Debris Flow Phenomena A Short Overview Chiara Calligaris and Luca Zini University of Trieste Geosciences Department Italy 1. Introduction Debris flows are one of the most dangerous and destructive processes affecting the second order streams in the mountain areas Cavalli et al. 2005 Boniello et al. 2010 Santi . 2008 . This very common phenomenon in the Alpine environment is a type of landslide defined by several authors Varnes 1978 Hutchinson 1988 Pierson 2005 Pierson and Costa 1987 Coussot and Meunier 1996 Hungr et al. 2001 trough focusing on the involved material on the water saturation and on the mass velocity. Debris flows usually consist of a complex mixture of fine clay silt and sand and coarse gravel cobbles and boulders materials with a variable water quantity Nettleton et al. 2005 . The outcoming mixture has a behaviour similar to a viscous slurry with a high density 60 to 80 by weight solids Varnes 1978 Hutchinson 1988 Pierson 2005 . The same Hutchinson 1988 is describing them as wet concrete . These phenomena are rapid mass movements gravity induced able to transport large quantities of sediments and wood downslope producing complex distribution of deposits and eroding surfaces along their flowpath Remaitre et al. 2003 . Several other classifications try to define these processes. For example Aulitzky in 1982 provided a classification focused on the typologies of the materials involved making a macroscopic distinction between the rocks and the engineering soils. Pierson and Costa in 1987 proposed their classification basing it on the sediment concentration and on the average flow velocity. Paoluzzi Coussot and Meunier in 1996 described debris flow as a function of sediment concentration and material typology between .
