The Risk Evaluation Of Debris Flow In Southem Liaoning

Debris flow is one kind of burst characteristics geology disaster that is often happened inmountain areas. It belongs to a special torrent that has huge destructive force. Our country isvery mountainous and the mountainous area is2/3of the total land area. The terrain is steepand the mountains are arranged in a crisscross pattern. The types of Quaternaryunconsolidated solid materials are abundant and our country mostly belongs to monsoonclimate zone. Therefore the debris flow has a wide distribution and the activities are frequent,which makes our county become the debris flow prone area in the world. With thedevelopment of the society and the increasing extent of damage that human beings make tothe ground vegetations, the degree of harm that debris flow has become more and moreobvious. The risk evaluation of southern Liaoning could reflect the current status anddevelopment trend of debris flow. It is the key to urban earthquake prevention and disasterreduction and also to the assurance of people’s life and property.The paper uses southern Liaoning debris flow as research materials and firstlysummarizes the researches on the risk evaluation of debris flow at home and abroad, andintroduces the purpose, significance, content and technical route of the paper research. Usingthe major four water systems as specific object of research, the paper analyzes the topography,geological structure, precipitation, human activities and earthquake of the area and exploresthe influence these factors have on the outbreak of debris flow. Considering the moreaccuracy of the data, the paper applies the fuzzy comprehensive evaluation of analyticalhierarchy process and the comparison of entropy method to analyze the degree of debris flowhazard in the area. The paper uses the debris flow that happens in southern Liaoning in2001as evaluation background. The rainfall amount utilizes the intraday data from each monitoringstation. Choosing rainstorm, basin relative height difference, drainage area, the main ditchlongitudinal slope angle, the length of the main ditch, bulk density, thickness of deposits, dragcoefficient as eight indicators building evaluation system, the paper studies on33debris flowsingle ditches, establishes the framework of index weight, identifies indicators weight, andevaluates the risk of debris flow in Southern Liaoning. Four water system single ditch debrisflow risk degree levels are divided from low to high: medium, high, very high, and verydangerous. Evaluation results indicate that the risk degree of southern Liaoning debris isoverall high. Based on the fuzzy comprehensive evaluation of analytical hierarchy processand the entropy method, the evaluation on the risk degree of regional debris flow ditch hasbetter consistency. The risk level of Tangjiagou, Chechanggou, Paoshougou, and Zhaotun-Laomiaoling include very dangerous and very high and the possibilities of theoutbreak of debris flow are the biggest. The fuzzy comprehensive evaluation of analyticalhierarchy process could intuitively feedback problems, but because of errors and the lack ofexperience of the experts, the results of the analysis may have deviation; the use of entropymethod just is able to make up for the deficiency that analytical hierarchy process method hasin the analysis of the impact factors of debris flow. The results could have good continuity atthe regional level.The fact that risk degree level of southern Liaoning debris flow is high is mainly causedby the dramatic increase in the human activities interference strength of southern Liaoning inrecent years. Therefore we should deeply understand that the debris flow risk evaluation hasbecome an important task to develop mountain economies and to protect people’s life andproperty safety in the mountains. Creating possibilities to better forecast of debris flow in thefuture and making scientific and effective measures and recommendations all have greatsignificance to post-disaster reconstruction and the long-term socio-economic development.