Kourosh Shirani; Abdollah Seif; Mohamad Sharifikia
Abstract
Launching satellites with Synthetic Aperture Radar (SAR) sensors onboard, purposely built for differential interferometry (D-InSAR) applications opened new opportunities for mapping and monitoring slow ground deformations and even high speed landslides, for the updating of regional landslide inventories ...
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Launching satellites with Synthetic Aperture Radar (SAR) sensors onboard, purposely built for differential interferometry (D-InSAR) applications opened new opportunities for mapping and monitoring slow ground deformations and even high speed landslides, for the updating of regional landslide inventories as well as retrieving time series of landslide movements. The present work has been done by using DInSAR method, with objection of performance assessment of two radar sensors in order to detecting, monitoring and landslide inventory mapping in Dena Mountain of Zagros located in south of Isfahan province. For this purpose two sets of images including 17 and 21 RADAR images of PALSAR and ASAR sensors from ALOS and ENVISAT satellites were chosen and processed by D-InSAR method. The preliminary processing result showed that 16 interferometer images were suitable for the next processing stages from all applied data sets. The outcome of interfrogram analysis along with field checking showed that 914 segments are marked as landslides anomaly over the area of 13578 ha. The maximum land sliding activities was identified as 1.58 meter vertical displacement during May 2010 to September 2011. Furthermore, results showed differential interferometry method applied for above mentioned frequencies has sufficient accuracy and conform efficiency for landslide detection, monitoring and distribution mapping compared to other methods (field survey in extend area, aerial photo and optical satellite images). Out of this two frequency, low frequency of PALSAR images has better ability in landslide zonation due to its capabilities such as longer wavelength and reduced incoherency. Where the high frequency of ASAR images can offer more details of the landslides due to its shorter wavelength.
Shahram Roustaei; Mahasa Roustaei; Mohamad Sharifikia; Jamshid Yarahmadi
Abstract
Differential synthetic aperture radar interferometry (D-InSAR) has become a useful technique for monitoring ground movement. The technique enables the analysis of very small ground movements in continuous and large areas and has the advantages of high accuracy, high resolution, all-weather adaptability, ...
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Differential synthetic aperture radar interferometry (D-InSAR) has become a useful technique for monitoring ground movement. The technique enables the analysis of very small ground movements in continuous and large areas and has the advantages of high accuracy, high resolution, all-weather adaptability, low cost and inaccessible area coverage. Thus, D-InSAR has been widely used for investigation of geologic hazards, such as subsidence, landslide, earthquake, and volcanic activity. In this research, D-InSAR technique was applied for detection of unstable slopes and determining moving displacement rate. For this purpose, eight SAR images of PALSAR sensor of ALOS satellite were selected for processing based on D-InSAR approach. Obtained results were validated by field observations prates. This paper is only represented results related to image pair processing of 5th July to 5th October 2007 with 92 days interval. Garm Chay watershed with 940 km2 area is located in North Eastern and 40 km far from Miyaneh in Eastern Azerbyjan, Iran. This region with 380 landslides is considered as one of the unstable landslide proven area in Eastern Azerbyjan. Occurrence of these slides caused heavy damages to rural properties and arable lands. As a result, Sovin village in north western part of this watershed was moved to other safesite. The results clearly showed that some old stabilized landslides were still active. Because of their proximity to local stream networks (check the possibility for stream displacement), they can be considered as important sources of sediment yield. Before mentioned period, the maximum displacement was calculated 5.8 cm in landslide surface near to Avin, Atajan and Benavaran villages. The results from this method should be validated by geodetic methods and field obsevations.
