Application Of RS And GIS In Geological Disaster Risk Assessment

Crustal fracture activities is distributed universally because of china's complex geological and geographical environment and quite different space-time of climatic conditions, thus china is a country where collapse, landslide, debris flow and other geological disasters occur frequently. Meanwhile intensity and frequency of China's activity is higher than other countries.The world's major earthquake in the mainland,about a quarter to one third,occurred in China.As undulating terrain in the areas affected by earthquake, complex geological structure, coupled with frequent aftershocks, the local geological environment is influenced and a large number of secondary geological disasters are induced. Especially the earthquake occurred in the mountainous areas often causes severe deformation of the surface and a lot of landslides and results in transportation and communication interrupted. Ground survey can not meet requirement of the timeliness, saving it is difficult to quickly reach the affected area. Coupled with frequent climate abnormal in the earthquake areas and rainfall frequency, so optical imaging alone is difficult to meet the requirements, and application of the multi-source remote sensing technology and GIS technology to carry out investigation and assessment of geological hazards is the inevitable trend of modern high-tech development. Although remote sensing technology in regional geological hazard investigation and evaluation has made many successful experiences, most stay the disaster point's extraction and macro-regional evaluation in the use of optical images. The fine interpretation of geological disasters by comprehensive utilization of high-resolution airborne and satellite-borne remote sensing images and GIS technology, pregnant disaster background analysis and risk assessment research are relatively small. This paper, taking Qing Chuan and Ping Wu County as the example, has made understanding and research results in the systematic study, as follows:(1) More systematic methods and system which utilizes satellite-borne airborne optical and microwave remote sensing to research geological disaster is initially established; combined with the causes and development characteristics of geological disasters, method of interpretation of geological hazards is improved on the basis of previous research; combination of the study area, the roles of geological disaster survey and risk assessment through remote sensing technology are clarified.(2) Key technologies of remote sensing in the study of geological disaster, including data source selection, radiometric correction, geometric correction, ortho correction, geometric characteristic radar image and interference-in radar technology.(3) Taking a comprehensive remote sensing experiment before crossing the satellite, the satellite after the transit, and simultaneously and simultaneous multi-source data acquisition, geological hazards associated factors required are extracted based on collaborative processing of multi-source data; the ground survey work and radar calibration work are performed targetedly and purposefully to the important study areas.(4) By comparing the disaster-before multi-channel spectral image channel with disaster–after X-band airborne radar image channel extraction results, the changes in river channels can be quickly detected, which is better for the extraction effect of a large landslide leading to channel blocking. Using 0.5 meter X-band airborne radar images can more clearly identify landslide, which is more fast, relative to the ground investigation,and the geological hazards monitoring is more reliable and applicable when it clouds and rains.(5) The comparative analysis on landslide is performed to the major geologic hazards using multi-temporal SPOT, TM, aerial optical, radar images and other. It is proved that high-resolution and multi-polarization SAR image is very effective to interpretation of the landslide, barrier lakes, bridges, housing and so on. Especially in the clouds, rain, night and other bad weather conditions and failing to access to high-resolution optical images, SAR,as a supplementary of optical remote sensing,can provide timely and accurate information to make emergency command and aid decision.(6) Combined with field investigation and using of multi-source remote sensing data, geological disasters pregnancy background, the growth conditions and the extraction of host body are fulfilled. In the study of geology background and disaster distribution the hazard assessment index system is identified with mathematical evaluation models that appraise the geological hazards of the regional risk. By comparative analysis, selecting high precision model makes risk assessment and risk evaluation to study area.Risk assessment, analysis results and status of geological hazards are in good agreement, which have some reference value for disaster reduction and relief.