Study On Geological Environments Of Debris Flow Using Remote Sensing Image Based On DEM In Dongchuan

Debris flow is a kind of paroxysmal geologic hazard which is familiar in the west mountainous areas of our country. It directly threatens the safety of people's life and property and hampers local economic development. As the main factor to development of debris flow, the geological environment related to debris flow is gradually in-depth researched. The geological environment which impacts the development of debris flow includes topography and geological conditions: topography provides potential energy conditions and endows debris flow with enery for corroding, transiting muds and rocks; the geological condition provides the rich solid matter origin for the debris flow Researching and surveying the geological environment background elements related to the formation and development of debris flows have the vital practical significance and value to people for mastering natural hazards' rule and alleviating and defending hazards measures.The development of Remote Sensing and Photogrammetric technologies offers rich data sources and advanced methods to model the earth's surface for researching geographic phenomena such as debris flow. As a kind of mathematic expression for terrain, Digital Elevation Model (DEM) can provide basic three-dimension (3-D) analyzing data. 3-D images of remote sensing which is generated from remote sensing images based on DEM can reflect detail characteristics of debris flow more direct, accurate and realistic and can realize quantitative expression of debris flow's correlation essential factors.This article took Dongchuan District of Kunming as the study area. On basis of fully collecting and researching predecessors' research results, this paper took 1:50000 topographical data as the basis topographical sorce to discusse methods of high-precision DEM modal's approach and took Landset-7 ETM+ data as the main source of remote sensing data, combining theoretical knowledge of remote sensing, to discusse the key remote sensing technology on the study of debris flow, and in this way realized interpretation of the geological environment; Based on DEM produced 3-D remote sensing image and realized characteristics Elements of the quantitative identification; Finally realized evaluationof debris flow risk. Based on the above ideas, this paper finally achieved the following results: Based on DEM, factors (such as altitude, hypsography, slope, etc) and characteristic lines (such as ridge lines and valley lines) which correlate with physiognomy morphological character of study area were extracted and character statistics were analyzed; Based on ETM+ remote sensing image, lithology, vegetation and other information related to geological environment of study area were automatically extracted and linear structures automatic extraction method was developed; Based on 3-D remote sensing image of study area, the quantitative identification of debris flow was realized. In this paper, 117 debris flows were successfully interpreted and their morphological characters (such as drainage area, relative altitude, valley bed longitudinal slope, average inclination, etc) were expressed quantificationally; In this paper, many controlling assessment factors that were used to assess region risk of debris flow were chosen. Based on multi-factors correlation analysis in Grey System Theory, those factors were carried on sorting and each factor was given a logical weight. Accordingly, this paper evaluated the risk of debris flow of study area and assessed the result. Contrasting the district result and distribution status of debris flow point on study area may know that the result tallies well with the status quo of debris flow point.This applying research not only provides the basic data and scientific basis for drawing measures and establishes a good foundation for further understanding the law of debris flow on study area, but also provides a new reference for natural hazards survey methodology. The practice has proved that 3-D visualization of remote sensing images which are structured based on DEM is feasible applied to single debris flow identification, pregnant hazard background checks, risk evaluation study and so on.