Investigation Of Typical Natural Hazards In Thailand And China With Time Series SAR Data Analysis

SAR data and its applications are well-known and widely used to encourage various utilizations in many areas.The advantages of SAR images are independent from daylight,cloud coverage and weather conditions which acquired the potential of monitor dynamic processes on the earth surface in a reliable,continuous and global way as well.Especially,In the case of disaster management which requested the observation intervals for the systematic monitoring of the phenomena.Moreover,the current SAR systems and the availability of historical SAR data,they have achieved many important advantages to exploit SAR dataset in various operational applications.It is not only utilizations from both amplitude and phase information,but polarimetric SAR is widely used.The estimation of flood extent in southern Thailand during December 2016,SAR change detection technique is used to analyze Sentinel-1 images from both VV and VH polarizations.The potential of dual polarizations combination for flood change detection is explored and can efficiently evaluate the decreasing percentage of affected flood areas in southern Thailand.Time-series InSAR techniques are involved in this work in order to estimate the temporal characteristics of surface deformation by combining information from multiple SAR datasets acquired over time.The SAR datasets of Sentinel-1,ENVISAT ASAR,ALOS PALSAR achieved disaster monitoring i.e.,land subsidence in Bangkok and landslide in Three Georges region.The analysis of land subsidence in the metropolitan area of Bangkok using SAR Interferometry has already identified the displacement areas and rates.The interferometric processing of Sentinel-1A interferometric datasets during 2015 to 2017 has been achieved subsidence detection with mean subsidence rates between-22.3 to 13.5 mm/year.(refer to the SAR Line-of-Sight(LOS)).In the case of landslide monitoring in Three Georges region found some significant deformations in Badong using D-InSAR technique and large displacement in Badong is detected with monitoring by the three SAR datasets for landslide assessment.The mean deformation velocities in the areas are approximately-14 to 50 mm/year.estimated using PS-InSAR technique.Finally,the potential of multiple SAR datasets achieved to apply for disaster monitoring in different purpose.Although SAR images are seldom affected by atmospheric conditions,but only suitable SAR satellites,techniques and methods which are effective to avoid the limitations of environmental areas will provide reliable information.