Studies On The Causes Of Formation And Evolvement Trend Prediction Of Debris Flow Of The Gangou Qiao Village, An'Xian County

5.12 Wenchuan Earthquake of 2008 not only causes a large number of casualties and property losses, but also triggers various kinds of secondary geological disasters, including landslides, unstable slopes, collapses, perilous rocks, debris flows, etc. There had been outbreak records of Gangou Qiao debris flow before the 5.12 Earthquake, which makes it step into a period with high frequency of outbreaks.Through analysis of the circumstances of Gangou Qiao debris flow happened in An'Xian County, this paper studies its causes of formation and laws of development and evolvement, detailed calculations of the debris flow's characteristic parameters and a systematic prediction over this disaster is also made, and finally the author proposes effective preventing and curing schemes on the basis of these fore-going results.This paper starts from these following factors of the particular area: hydrology, meteorology, topography, geomorphology and geological structures, making a macro-analysis of the geological circumstance of Gangou Qiao debris flow district, and even a detailed analysis of the following aspects of the debris flow gully: water area, source area, circulation area and accumulation area, through studying its causes of formation and evolvement process according to watershed characteristics, this paper evaluates its evolvement trend as well as the risk. Secondly, according to the three basic formation conditions: terrain, loose material resource, and the hydrodynamic condition, the author does the systematic prediction through mathematical model: including the occurrence time, scale, harm scope and degree of debris flow might break out in future. The part of analysis on topographical condition adopts forming index N of valley longitudinal profile to predict; adopts the approach of provenance analysis to study the factor of solid materials; Maximum entropy spectrum analysis method is used in cycle analysis of hydrodynamic conditions, and then the author makes prediction with gray model. Finally, combining with fore-going research results and the actual situation in the study area, this paper presents possible treatment measures.