Study Of The Risk Evaluation For Dadonggou Debris Flow Basin

Debris flow is a special flood existing at mountains or valleys which contains alot of loose rock and sediment, considers significant amounts of water such as theaccumulation of heavy rain or snow as the main motivation, and is a kind ofgeological disaster the same as landslide, collapse and earthquake. Meanwhile thefluid which integrating together by solid and liquid has the characteristics ofexploding suddenly, flowing faster, shorter time of the outbreak and large destruction,and the majority of this geological disaster occurred in mountainous slopes, valleysand other areas.Our country is a mountainous country, and70%of the land areas are mountains,especially in Inner Mongolia, Sichuan, Yunnan and other places where have a largearea of the mountain covering and steep terrain, which creating a good terraincondition for the occurring of debris flow. China is located between the Eurasian plateand the Pacific plate, the intense seismic activity also played a catalytic role for debrisflow occurring. Once the debris flow occur, it will inevitably cause significantdamage on hydropower engineering, traffic facilities, ecological environment and thelocal people’s life and property security. Therefore, the risk assessment of debris flowhas important scientific significance and value.This article takes the Dadonggou debris flow which on the right bank of BaichaRiver in a water reservoir zone which under a pumped storage power plant in InnerMongolia Chifeng Province. In this paper, we investigate in detail at the topography,lithological characteristics, formation area, circulation area and stacked area of thedebris flow by collecting local data, hydrologic analysis, field geological survey andother methods, and analyze the causes of debris flow in the view of the test result ofthe debris flow deposits field sieve analysis.First, by researching the hydrological data of Keshikten Banner, combined withthe empirical formula of "Sichuan Province Hydrology Manual" and "Liaoning Provincial Hydrology Manual", we studied the dynamics and motion characteristics ofDadonggou debris flow. The results contain the flow rate, flux, once out of the amountand impact force of debris flow, at the same time, there are detailed in this paper aboutthe scope of the debris flow hazards.Second, selecting nine evaluation indexes including the size of the landslides, thefrequency of occurrence and the basin area, calculating the weight of each index bythe least square method of the weight subjectively and the factor analysis methodobjectively, we can bestow weighing to the nine evaluation indexes based oncombination weighing method of distance function. Quantitative evaluate thedangerousness of Dadonggou debris flow by fuzzy comprehensive evaluation methodand Liu Xilin evaluation methodology. Qualitative assess the hazard of Dadonggoudebris flow by applying the Arcgis software, considering the division of debris flowdangerousness degree by two factors that the slope of accumulation area and thehorizontal distance to alluvial fan channel.Subsequently, quantitatively evaluate the vulnerability of debris flow by LiuXilin evaluation model, and grid compute the assessment factors applying the Arcgissoftware based on physical, economic vulnerability fitting formula in order to zonethe vulnerability of debris flow.Finally, obtaining risk degree according to Liu Xilin risk assessment model"degree of risk=hazard×vulnerability degree", grid computing the results ofdangerousness and vulnerability division, we can get the map of Dadonggou debrisflow risk zones.