Ice Avalanche Deformation Monitoring Based On Optical Remote Sensing Image Correlation Technology

In recent years,with the development of production and construction activities in China,the problems caused by geological disasters such as ice avalanche and rock avalanche are becoming more and more serious.With the development of remote sensing technology,it is possible to monitor disasters in a large scale.Compared with In SAR technology,which is susceptible to vegetation and incoherence,and high cost of Li DAR technology,optical remote sensing has the advantages of high spatial resolution,short revisit period and large database stock,so it has the potential of wide application.However,in traditional research,optical data is mostly used for qualitative interpretation of geological disasters,and quantitative deformation information cannot be obtained.In view of the above problems,this paper studies the ice avalanche deformation monitoring based on optical remote sensing image correlation technology,and elaborates the relevant technical theories.Taking Tonghua landslide as an example,the accuracy analysis and band fusion of Sentinel-2 data are carried out.The remote sensing data of the Chalonglongbaqu of Parlung Tsangpo are processed,and the movement and stability of glaciers in the basin are analyzed.Finally,based on the above technical scheme,the time series deformation field of one year before the glacial avalanche disaster in Chamoli region of India,2021 is obtained,and the deformation characteristics and disaster-causing mechanism are analyzed in detail.The paper first describes the principle of image correlation,and the data pre-processing,correlation processing and error modeling post-processing are mainly introduced.The preprocessing mainly completes the ortho-rectification and resampling of remote sensing image,providing input data for image correlation;the correlation process is based on two algorithms,spatial domain correlation and frequency domain correlation,respectively;the purpose of error modeling post-processing is to remove all kinds of system errors in correlation results,so as to obtain the real and effective two-dimensional deformation field.Based on the data processing,taking Tonghua landslide as an example,the multi band monitoring results of Sentinel-2 data are evaluated by experiments,and further fusion is carried out,thus improving the monitoring accuracy.Finally,the theoretical accuracy and reliability of the technology are verified by simulation experiments.Based on the above theory,the paper takes the Chalonglongbaqu basin of Parlung Tsangpo as the research object,and interprets the geological disasters in the research area.On this basis,the deformation results are obtained by using the images of GF-2 and Sentinel-2.Finally,based on the results of remote sensing interpretation and quantitative monitoring,the movement and stability of glacier-1,the largest potential threat in the basin,are analyzed.The profile velocity curve of glacier main axis is drawn based on spatial domain correlation and frequency domain correlation,respectively.The results of two algorithms are consistent.On the one hand,the reliability of the results is verified.On the other hand,it is revealed that the technology is suitable for the research objects such as landslides and glaciers with medium motion and obvious surface texture.The successful extraction of deformation field in Chalonglongbaqu basin proves the feasibility of ground deformation monitoring based on optical remote sensing image correlation technology,but it is also necessary to confirm that the technology can obtain pre disaster deformation signals,so as to make effective early warning.Based on this,the paper further selects the glacial avalanche event in Chamoli area of India,2021 as the research object,and matches the 28 scenes of Sentinel-2 data in the previous year of the disaster,and analyzes the time series deformation characteristics of four points around the disaster.Finally,combined with historical remote sensing images and meteorological data,the causes of the disaster are analyzed and discussed.It is suggested that the glacier fault area was first affected by the landslide that occurred in October 2016,which resulted in fracture on the trailing edge.In the following time,the fracture gradually expanded,causing the ice-rock mass to gradually separate from the parent rock.The long-term small amount of precipitation in the second half of 2020 broke the dynamic balance of glacial supplement and melting,resulting in accelerated deformation in the region,and the sudden increase of snowfall in early February 2021 eventually led to the collapse of the glacier.In conclusion,the paper makes a deep study and discussion on the optical remote sensing image correlation technology from the theoretical and practical levels,and summarizes the advantages and disadvantages of the technology.With the further research and the launch of more optical satellites,image correlation technology will play an increasingly important role in the field of geological disaster monitoring.The results of this paper can provide reference for the application of optical remote sensing image in disaster prevention and mitigation.