Debris Flow Monitoring And Early Warning Method In WenChuan Earthquake Area

An important way to reduce debris flow hazard is debris flow monitoring and earlywarning. In the flood season after the5.12WenChuan earthquake, in WenChuan earthquakearea, especially in mid-August2010in three area debris flow, Sichuan,outbreaks of debrisflow Characterized by group properties, sudden occurring features, destructiveness andhazard chain effect. Comparison can be determined by debris flow in history after strongearthquake, in Wenchuan earthquake zone debris flows will continue for many years. whilethe impact of the earthquake has not been eliminated, April20,2013in Ya’an, SichuanProvince, A magnitude7earthquake occurred, the visible the earthquake debris flow disasterproblem will exist for a long time. Monitoring is to obtain the ideal way to study debris flowdata, Conducive to accurate understanding of the start-up and development process of thedebris flow, Early warning can reduce the harm to the maximum extent of the debris flowwhen it happen Therefore, the combination of the earthquake debris flow characteristics theearthquake debris flow monitoring and early warning research has important theoreticalsignificance and practical value.In this paper, investigating seven debris flow gully in typical of the three area inWenchuan earthquake zone, classification, research and monitoring system established onits basis, investigating a single instrument and means of monitoring warning together. Madethe following main results and conclusions:(1) After the earthquake to "8.13" before the debris flow event, combined with surveydata statistics draw toon ditch, burn Zhifanggou, more than50%of the rodeo groove and thetrench Zoumaling Slumping TYPE provenance of the total provenance amountsix mudslidestrench debris flow after the events of the "8.13" as the main research Slumping matter provenance is still the major source of more than40%of the total amount ofprovenance.Other types of debris flow material source are potential landslides, channeldeposits type source and slope shallow accumulation of deposits. Each of these sources arelikely transform into debris flow. The debris flow start-up mode include channel start-upform, blocking the collapse of the start-up form and slope erosion start-up form.(2) Debris flow monitoring system mainly consists of three parts, the front fieldmonitoring system, the intermediate data reception centers and back-end monitoring andearly warning system. This paper studies the front end of the field monitoring system, thefield monitoring demonstration zones has been built in the three area at last year, monitoringthe demonstration area using a variety of monitoring tools and methods, including: tippingbucket rain gauge, debris flow sonic mud level meter, video monitoring equipment, debrisflow contact disconnection instrument.(3) Explore the use of3D laser scanning precise topographic survey and calculation inthe course of the investigation of the debris flow,methods to calculate the volume of debrisflow deposits. First of all, before the flood season, the debris flow channel and governanceprojects (such as blocking dam reservoir)3D laser scanning through data de-noising, datainterpolation, data extraction step for3D point cloud data, and then create athree-dimensional grid, and finallymake a three-dimensional topographic map. Once anoutbreak landslides, debris flow and then the debris flow channel topography and treatmentproject to conduct a three-dimensional laser scanning again to obtain three-dimensionaltopographic map, the two terrain modeling, and Boolean operators can get the debris flowgully scouring and erosion of the scope and depth.(4)Combined with the characteristics of the area three monitoring system initiallyexplored a single monitoring instrument warning. Including:①rainfall indicator warning.②Debris flow depth level warning.③Rational use of the the debris flow contactdisconnection instrument and video monitoring debris flow warning.(5) In the single monitoring instrument warning method based on multi-monitoringtools, and explore monocolpate collaborative early warning method. To establish the use ofthe the rainfall warning indicators mudslides occur warning; judge whether the debris flowoccurred on the basis of existing governance projects for the debris flow trench debris flowfurther use of the mud bit of debris flow monitoring and early warning method of debris flowhazard warning; while the use of disconnection and video monitoring play a supporting role.Single debris flow for each monitoring instruments will be able to collaborative earlywarning and early warning. (6) Debris flow corresponds to four early warning level, the degree of urgency,appropriate information released, released There are four different levels of release objectsearly warning monitoring in the area three demonstration sites, namely: Management,monitoring responsibilities,threat objects and flood duty personnel, the duties of these fourtypes of objects, the object of attention different response to these circumstances, the initialdevelopment of the content and process of early warning information release.(7) Analysis of the2012typical debris flow instance monitored. The statistical rainfallmonitoring data, rainfall hour rain and precipitation index of pre-effective cumulativerainfall, the rainfall index statistics results are plotted in the graph of rainfall warning, checkto develop a single debris flow rainfall threshold indicators, analyze the soil level metermonitoring information and disconnection monitoring the results of the application ofthree-dimensional laser scanning method measuring the accumulation of debris flow volume,restore the whole process of the debris flow event.