Study On The Advanced Technology Of Forecast And Early Warning For Debris Flow And Its Application In Demonstration Area

In the mountainous areas in Southwest China, complex terrain conditions, abundant material sources, abundant rainfall, coupled with the recent frequent earthquake, these factors have provided favorable conditions for the debris flow outbreak. In order to improve the ability of prevention and mitigation disaster in mountain areas, in addition to strengthening project management, other nonengineering measures also have increasingly attracted people’s attention. Research results show that monitoring and early warning for the susceptibility area of debris flow disaster, forecasting time and scale of debris flow outbreak, and promptly inform the best escaping lines, disaster losses can be reduced in the maximum extent. Based on the survey of debris flow disaster, the study of critical threshold of rainfall, risk assessment and forecasting system are carried out in demonstration area. The main research work includes:1) The critical threshold of rainfall in the early warning of rainstorm debris flow is put forward. Because of the lack of historical rainfall data in the debris flow area, based on the analysis of rainfall pattern of the rainstorm debris flow and the method of critical rainfall threshold, the theory and method of determining the critical rainfall using debris flow formation mechanism are put forward, when the formation mechanism of debris flow is obvious.2) A method of extension-algorithm of optimal combination determining weights for evaluating the risk of debris flow is put forward. First, risk evaluation index is optimized by path analysis method. Then, an improved analytic hierarchy process is used to calculate the objective weights, and disaster entropy is used to calculate the subjective weights. On the basis of this, the optimal model is constructed by using the optimization theory. Matlab programming is used to solve the optimal weight and to standardize the processing, and ultimately to form the optimal combination weighting model. In the end, the risk assessment is put forward by using the extension-algorithm of optimal combination determining weight The basic ideas are: selecting the risk assessment index of debris flow, establishing the classical domain and the section area, establishing the evaluation object, establishing the correlation function, calculating the weight of each evaluation index based on the optimal combination weighting method, calculating the correlation value, and determining the risk grade of debris flow.3) A geological disaster forecast and warning system based on WEBGIS is constructed. Debris flow monitoring and warning is an important non-engineering measure for debris flow disaster prevention. Based on the analysis of the practical needs of debris flow warning system, the design structure and function of system, selection of development platforms and tools are discussed. According to the characteristics of GIS data, system database technology is proposed. The debris flow monitoring and warning information system is based on advanced WEBGIS technology, network technology and information transmission technology, which can provide technical support for the decision-making of the debris flow disaster prevention.4) Based on the advanced and mature Windows acquisition platform, telemetry data management system is developed with graphical user interface. The system database is stable and reliable using Access2003. And it has a function of remote telemetry data reception, distribution, processing(including data query, graphics, etc.) and storage. It can also send various instructions to the sensor of monitoring station. Also, it can remotely modify parameter of device and manage user privileges.5) The website of mitigation service is established. The relevant geological hazard information is published by Internet, which can provide scientific basis for further taking necessary measures, so as to reduce various losses of geological disasters.