Debris Flow Hazard Assessment Based On UAV Remote Sensing And GIS

China is a mountainous country, Mountain area of total area of more than two-thirds, the complex geological conditions make china become one of the most serious mud-rock flow disaster countries in the world. At the same time, the mud-rock flow disaster has become one of the most important geological disaster in Southwest Mountainous Towns in China. One of the effective means of prevention and control of debris flow disaster is construction management engineering, unpredictability, but since the outbreak of debris flow hazards in overclocking debris flow disasters, also can cause serious disasters and accidents. The formation of debris flow needs abundant solid material source, appropriate terrain, and plenty of rainfall. Due to earthquake damage to the structure of the mountain, geological disasters such as collapse and landslide is prone to occur in the trench and ditch sides. This provides a large number of source conditions for the mud-rock flow. The increase of the solid material source will change the scope of debris flow risk, even beyond the control ability of engineering design. Therefore, it is necessary to monitor the debris flow disaster, estimate disaster risk range, and evaluate the prevention and control of domain engineering capacity, and then decision support can be provided for geological disaster monitoring departments for reducing the loss of life and property.With the characteristics as high efficiency, high accuracy and convenient operation, the solid material source changing date can be acquired, rapidly and accurately, by the UAV(Unmanned Aerial Vehicle) remote sensing. In this paper, the solid material source variation in the study area has been estimated by GIS spatial analysis tool. Then, with the aid of FLO-2D debris flow simulation model, the accumulation scope of debris flow before and after solid material source changing has been simulated, and in view of the current source in the study area, the prevention and control ability of existing management engineering has be evaluated. Results show that under the condition of the current source, the scale of overclocking debris flow with recurrence period of 50 years will beyond the designed standards. By this conclusion, it provides data reference and decision support for geological disaster prevention and control work in environmental monitoring department. Specific work is as follows:(1)UAV remote sensing data acquisition. Take debris flow disaster monitoring project as an example, the application of UAV remote sensing in geological disaster monitoring system process has been introduced, including the preparing work, aerial work and data sorting;(2) Rapid processing of UAV data. Take the inner orientation elements correcting and exterior orientation elements correcting as the key technology of UAV data processing. Based on the camera POS data, the Pix4 Dmapper software is adopted to the aerial photo batch processing, eventually get DOM and DSM with higher quality of the study area.(3) Monitoring data in study area analysis. In this paper, firstly, the author visual interpreted the UAV remote sensing DOM in the study area, and compared the solid material source distribution before monitoring, then found out the new material source location and scope; secondly, the volume of new source has been calculated based on DEM/DSM; rainfall data in the study area were used to get the flood flow process line,finally, total flood volume and concentration volume of debris were acquired.(4) Debris flow numerical simulation. Under the precondition of existing projects, the author selected material source, topography and rainfall frequency as simulation parameters, and simulated the debris flow movement when rainfall frequency is 5% and 2% respectively by using FLO-2D debris flow simulation model, and the debris flow accumulation thickness and velocity diagram and then risk zoning map was got.(5) Disaster risk range estimating. In view of the risk zoning maps from numerical simulation results, debris flow range under rainfall frequency and material source was predicted, and disaster risk scope was estimated, then the basis for geological hazard prevention and control work can be provided.