Risk assessment of gas and oil pipelines due to land sliding hazard based on D-InSAR technique

Risk assessment of Maroun gas and oil pipelines due to land sliding hazard based on D-InSAR technique Mohammad Sharifikia, @ Associate professor, Tarbiat Modares University, Department of Remote Sensing- Iran Meral Poorhamzah, postgraduate in Remote Sensing, Tarbiat Modares University Abstract It is importance to note that Iranian oil company have to transfer this valuable enrage from one side to other side of country passing form several ridge and valley prone with several natural hazard. This is because the natural sources of oil and gas generally lied in south west part of Iran locally calling Manathegh Nafte Khize Jonoub (south oil field area). This area is closed to one of most active geological zone of Iran (Zakrose) covering thousands of kilometer from south east to north west. Supplying natural enrages to central port of country need to crossing from this zone which is suffering with several difficulties as well as neutral hazard. Out of neutral hazards can found to excite in this area, the landslide hazard is a main restriction for pipeline crossing over. The present research is dale with radar interferometry techniques applying for risk assessment and mapping over the oil and gas pipelines suffering to landslides hazard in the part of Central Zagros (Maroun-Esfahan). For this purpose, two individual radar dataset in C (ASAR) and L (PALSAR) band with deferent time were collected. Furthermore, the D-InSAR technique was applied for land surface movement and land displacement detection. The outcome map was showed the maximum rate of land displacement in this region is about ۷.۴ cm uplifted and ۳.۹ cm subsidence with duration of almost one year. this is due to shape of landslide over the area’s slop. Overlying the landslide map with the pipeline crossing route shown at lies three active landslides over the Maroun-Esfahan gas and oil pipelines. For investigation about this three landslide and damage estimation over the pipeline the field study has been done for accuracy assessment and land movement rat measuring and evaluation. Which, successfully identified and mapped ۳ landslides were located across the pipeline and damage it. Furthermore, map surveying by DGPS in RTK method over the one of landslide shown that sliding transfer ۲۰ m with falling ۱۰ m over the length of ۴۵ m of gas pipeline. moreover, the press of landslide made curvatures on straight pip hogging pipe ۴۳ cm. continued this landslide activation and more pressing in close further can make a fracture and pessimistic pipe expulsion. With can a kind of disaster if the event be close to settlements are. The outcome landslide map shown the active landslide points (small area) very well, but the main think need to suffusion information about interred area. For this exigency have to convert points data map to area as prediction hazard. For this proses and to understanding the amplitude of landslide hazard in area the information value model was applied for hazard zonation and mapping. The landslide hazard map resulting from D-InSAR technique as inventory map along with ۸ data set maps namely, lito-logy, soil, land cover, lineaments, faults, roads, derange pattern and slop, has been interred to model for zonation and hazard estimation over the area. Furthermore, this map was reclass in ۵ individual hazard and risk class from low to high risk. The hazard map analyses and calculation was show about ۲۰ percent of area study was marked as high and very high risk zone. This is mainly because of morphological and lito-logical exclusivity of area resulting by active tectonics. Crooning and overlaying the landslide hazard map with pipeline track has been shown ۲۸.۵ percent of line length crossing over the high and very high risk zone, where the ۵۲ percent was prone with low and very low risk zone. This mine that near ۱/۳ of mention pipeline length suffering from hazardous area which can classified as high risk part of pipeline. Interpreting the hazardous classes on the prediction map is an important concern in landslide prediction models. For this purpose, the prediction-rate curve was generated using validation group of landslide locations to validate the prediction map obtained. This rate curve explains how well the model and factors predict the landslide. Results from the success-rate curve are very promising, since the ۳% area predicted as the most hazardous, includes ۴۲.۳۵% of the total area affected by landslides, and this value grows to ۹۰%, when about ۲۵% area of highest susceptibility is considered. The prediction accuracy can be assessed qualitatively by calculation the area under cover. The total area equal to one means perfect prediction accuracy. In this model ratio area was ۰.۶۳۳ that means the prediction accuracy was ۶۳.۳%. Keywords: Differential SAR Interferometry, PALSAR, ASAR, Landslide, Oil and Gas Pipeline risk