A Research On Debris Flow Disaster Risk Assessment In Mianzhu City Of Sichuan Province

The Mianzhu city belongs to Deyang City in Sichuan Province, it attached at jointof the Western Sichuan Plain and Qinghai-Tibet Plateau, which is in the South ofShifang, West of Wenchuan, North of Mao county, East of An county. Mianzhu citycovers an area of1246.23km~2, the total population of51.24million. The landscape ofMianzhu City shows a terrain west north to east south which is Consist of a plain, lowmountains, middle mountains, alpine landforms, Mianzhu is located in the LongmenMountain tectonic zone, stratigraphic occurrence changed greatly; Its region riches ingroundwater and surface water, groundwater is mainly bedrock fissure water and porewater loose; human engineering activities more strongly, mainly roads and bridges,water utilities, urban construction. In general, the geological environment in Mianzhucity is complex which is designated as geological hazard prone areas in SichuanProvince. The debris flow is one of main geologic disasters, after the5.12Wenchuanearthquake,59debris flow were found in Mianzhu City by remote sensinginterpretation and field investigation. In order to identify environment background, inwhich the debris flow disasters of Mianzhu city, to find out the distribution and theconditions for the formation of debris flow disasters, determine for the Mianzhu city disaster prevention and mitigation services and reduce the economic loss caused bydebris flow, there is an urgent need for a complete set of debris flow risk assessmentmodel and method. In this paper, reasonable discussions have been done into thisresearch area, and major outcome has been obtained as follows:(1) This paper has proposed the clear debris flow risk assessment methodmentalily of Mianzhu city, also survey of field-collection of information–dateanalysis–factor quantification–model evaluation–obtains the result–result analysis,establish the Mianzhu debris flow disaster risk assessment system.(2) This paper analysis the temporal and spatial distribution of debris flow disaster,studied the development of debris flow characteristics and formation conditions, andbased which, select fault, stratum lithology, elevation, slope, slope direction, river andthe average annual rainfall of Mianzhu city as the debris flow risk assessment of themain evaluation index, and through the AHP mathematical model to calculate theweight of each factor.(3) This paper summed up the debris flow disaster of Mianzhu city risk appraisal’sway, namely the appraisal’s way was this kind of flow of analysis of characteristic ofgeological hazards–formation mechanism–sensitive factorial analysis and thequalitative analysis inference–mathematical model super imposition analysis–qualitysynthetic evaluation, and has annotated this flow well with Arcgis, has obtained theachievement chart finally.(4) The figure shows the results from the assessment district that, research area ofdebris flow risk can be divided into four levels: high risk zone (8.54%), in the dangerzone (20.25%), low risk areas (34.54%), no danger zone (36.66%).On the basis ofdetermining the risk prevention of debris flow, the related proposal were put forward.