تداخل‌سنجی تفاضلی تصاویر راداری به منظور تبیین خطرپذیری شبکه انتقال نفت و گاز مارون از مخاطره زمین لغزش

تداخل سنجی راداری تکنیکی کارآمد برای رصد پویایی سطوح است که به کمک آن میتوان ناپایداری سطوح به خصوص سطوح دامنه ای که مخاطرات لغزشی را پیامد دارند، تشخیص داده و مورد پایش قرار داد. تشخیص این مخاطره علاوه بر خطرات شناخته شده و متداول آن در پاره ای مواقع می تواند تاسیسات و زیرساخت های مدفون را آسیب رسانیده و خسارات و خطرات فراوانی به همراه داشته باشد. شبکه انتقال نفت از جمله این زیرساخت هاست که با عبور از نواحی کوهستانی و مستعد لغزش عموماً در خطر شکستگی و نشت قرار دارند. طبق مطالعات صورت گرفته، پژوهشی به منظور تعیین خطرپذیری خطوط لوله با تکنیک تداخل سنجی راداری در منطقه مورد مطالعه یافت نشد. تحقیق حاضر خطرپذیری شبکه نفت و گاز مارون (مارون- اصفهان) در زاگرس مرکزی از مخاطره زمین لغزش به کمک تکنیک تداخل سنجی رادری را هدف داشته است. بدین منظور داده های دو سنجنده راداری در باند c و l در مقاطع متفاوت زمانی دریافت و مبتنی بر روش تداخل سنجی تفاضلی میزان تغییرات سطح و جابجایی های آن محاسبه شد. بر این اساس نرخ حداکثر جابجایی در منطقه حدود 7/4 سانتی متر بالاآمدگی و 3/9 سانتی متر فروافتادگی حاصل شد. پس از آن صحت نتایج بدست آمده از مرحله آزمایشگاهی، در پیمایش میدانی با بازدید از 3 زمین لغزش واقع در مجاورت خط لوله و تطبیق مکانی آن ها با یافته های آزمایشگاهی سنجیده شد. سپس پهنه بندی خطر آتی زمین لغزش در 5 کلاس خطر با مدل تجربی ارزش اطلاعاتی تهیه و صحت سنجی شد. مستند به این نقشه، حدود 20 درصد سطح منطقه در کلاس خطر زیاد و بسیار زیاد طبقه بندی شده است. منطبق سازی نقشه کلاس بندی خطر زمین لغزش با مسیر خط لوله نشان داد که 28/5 درصد از طول خط لوله مورد مطالعه در کلاس خطر زیاد و خیلی زیاد، و حدود 52 درصد از آن در کلاس خطر کم و بسیار کم قرار گرفته اند. 

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 hazardbased on d insar techniquemohammad sharifikia, @ associate professor, tarbiat modares university, department of remote sensing iranmeral poorhamzah, postgraduate in remote sensing, tarbiat modares universityabstractit is importance to note that iranian oil company have to transfer this valuable enrage from one side to other side ofcountry passing form several ridge and valley prone with several natural hazard. this is because the natural sourcesof oil and gas generally lied in south west part of iran locally calling manathegh nafte khize jonoub (south oil fieldarea). this area is closed to one of most active geological zone of iran (zakrose) covering thousands of kilometerfrom south east to north west. supplying natural enrages to central port of country need to crossing from this zonewhich is suffering with several difficulties as well as neutral hazard. out of neutral hazards can found to excite inthis 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 theoil 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 mapwas showed the maximum rate of land displacement in this region is about 7.4 cm uplifted and 3.9 cm subsidencewith duration of almost one year. this is due to shape of landslide over the area’s slop. overlying the landslide mapwith 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 donefor accuracy assessment and land movement rat measuring and evaluation. which, successfully identified andmapped 3 landslides were located across the pipeline and damage it. furthermore, map surveying by dgps in rtkmethod over the one of landslide shown that sliding transfer 20 m with falling 10 m over the length of 45 m of gaspipeline. moreover, the press of landslide made curvatures on straight pip hogging pipe 43 cm. continued thislandslide activation and more pressing in close further can make a fracture and pessimistic pipe expulsion. with cana 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 tosuffusion information about interred area. for this exigency have to convert points data map to area as predictionhazard. for this proses and to understanding the amplitude of landslide hazard in area the information value modelwas applied for hazard zonation and mapping. the landslide hazard map resulting from d insar technique asinventory map along with 8 data set maps namely, lito logy, soil, land cover, lineaments, faults, roads, derangepattern and slop, has been interred to model for zonation and hazard estimation over the area. furthermore, this mapwas reclass in 5 individual hazard and risk class from low to high risk. the hazard map analyses and calculation wasshow about 20 percent of area study was marked as high and very high risk zone. this is mainly because ofmorphological and lito logical exclusivity of area resulting by active tectonics. crooning and overlaying thelandslide hazard map with pipeline track has been shown 28.5 percent of line length crossing over the high and veryhigh risk zone, where the 52 percent was prone with low and very low risk zone. this mine that near 1/3 of mentionpipeline 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. forthis purpose, the prediction rate curve was generated using validation group of landslide locations to validate theprediction map obtained. this rate curve explains how well the model and factors predict the landslide. results fromthe success rate curve are very promising, since the 3% area predicted as the most hazardous, includes 42.35% ofthe total area affected by landslides, and this value grows to 90%, when about 25% area of highest susceptibility isconsidered. the prediction accuracy can be assessed qualitatively by calculation the area under cover. the total areaequal to one means perfect prediction accuracy. in this model ratio area was 0.633 that means the predictionaccuracy was 63.3%.keywords: differential sar interferometry, palsar, asar, landslide, oil and gas pipeline risk