جستجوی مقالات مرتبط با کلیدواژه "geomorphic hazards" در نشریات گروه "علوم انسانی"
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مخاطرات ژئومورفیک، به طور مستمر و در طول تاریخ در نواحی مختلف کره زمین اتفاق افتاده و همچنان ادامه دارد. ولی این وقایع را زمانی به عنوان یک مخاطره می شناسیم که سکونتگاه های انسانی تهدید کند و باعث خسارت به بناها، تاسیسات و تجهیزات ساخته دست بشر شود. همچنین دیگر از آنجا که بشر تا به امروز قادر به جلوگیری از وقوع بسیاری از این مخاطرات نبوده، لذا بهترین راهکار، دوری از این مخاطرات است. ولی با این حال بسیاری از سکونتگاه های انسانی در موقعیت های خطرپذیر به لحاظ مخاطرات ژئومورفیک قرار گرفته اند که تهدیدی بالقوه برای آنان محسوب می شود. بنابراین می توان با شناسایی نواحی پرخطر و امن سکونتی، هم برای مقابله با مخاطرات آماده شد و هم اینکه در توسعه ها و ساخت و سازهای آتی، نواحی امن سکونتی را در برنامه ریزی های شهری به کار گرفت. بر این اساس، تحقیق حاضر با این دغدغه انجام گرفت تا پهنه های امن سکونتی در استان گیلان، که یک استان پرمخاطره به لحاظ مخاطرات ژئومورفیک محسوب می شود، از طریق تحلیل فضایی، شناسایی شود. روش تحقیق از نوع آمیخته یا ترکیبی (کمی و کیفی) بوده و برای جمع آوری داده و اطلاعات، ترکیبی از دو روش کتابخانه ای و میدانی به کار برده شده است. نتایج این تحقیق نشان داد بر مبنای نظرات متخصصان و کارشناسان، مهمترین مخاطرات ژئومورفیک که به عنوان تهدیدی برای مناطق شهری استان گیلان تلقی می شود به ترتیب شامل زلزله، سیل، زمین لغزش، فرسایش، فرونشست و روانگرایی می شود. به لحاظ پراکنش فضایی نقاط امن سکونتی نیز بر مبنای آنچه از خروجی مدل فازی در نرم افزار GIS به دست آمد، 51.5 درصد از مساحت استان گیلان را سطوح ناامن و نسبتا ناامن به لحاظ مخاطرات ژئومورفیک دربرگرفته است. از سوی دیگر پهنه های امن و نسبتا امن، 23.4 درصد از سطح استان گیلان را شامل می شود و 25.1 درصد از مساحت استان را نیز پهنه با امنیت متوسط دربرمی گیرد.
کلید واژگان: تحلیل فضایی, استان گیلان, مخاطرات ژئومورفیک, پهنه های امن سکونتیGeomorphic hazards have occurred continuously and throughout history in different areas of the globe and continue to do so. But we recognize these events as a danger when they threaten human settlements and cause damage to man-made buildings, facilities, and equipment. Also, since humanity has not been able to prevent the occurrence of many of these dangers, the best solution is to stay away from these dangers. However, many human settlements are placed in risky situations in terms of geomorphic hazards, which is a potential threat to them. Therefore, by identifying high-risk and safe residential areas, it is possible to prepare to deal with risks and to use safe residential areas in urban planning in future developments and constructions. Based on this, the present research was conducted with this concern to identify safe residential zones in Guilan province, which is considered a high-risk province in terms of geomorphic hazards, through spatial analysis. The research method is mixed or combined (quantitative and qualitative) and a combination of library and field methods was used to collect data and information. The results of this research showed that based on the opinions of specialists and experts, the most important geomorphic hazards that are considered as a threat to the urban areas of Guilan province include earthquakes, floods, landslides, erosion, subsidence, and liquefaction, respectively. In terms of the spatial distribution of safe residential areas, based on what was obtained from the output of the fuzzy model in the GIS software, 51.5% of the Guilan province is covered by unsafe and relatively unsafe levels in terms of geomorphic hazards. On the other hand, safe and relatively safe zones cover 23.4% of the area of Guilan province, and 25.1% of the area of the province is covered by the medium security zone.
Keywords: Guilan Province, Spatial Analysis, Geomorphic Hazards, Residential Safe Zones -
رشد شتابان جمعیت شهری پاوه و توسعه شهری آن در سال های اخیر از موضوعات مورد توجه برنامه ریزان شهری منطقه بوده است. هدف از این پژوهش بررسی تاثیرات فرم و فرایندهای ژیومورفولوژیکی در توسعه شهری و تحلیل مخاطرات محیطی پاوه است. در این راستا با مطالعات میدانی فرم ها و فرایندهای ژیومورفولوژیک منطقه شناسایی و نقشه ژیومورفولوژی منطقه در مقیاس 25000/1 تهیه گردید. مهم ترین محدودیت های ژیومورفیک توسعه فیزیکی شناسایی شد و وضعیت بخش های مختلف شهر پاوه در ارتباط با این محدودیت ها مورد تحلیل قرار گرفت. مخاطره زمین لغزش به عنوان عامل محدودکننده مهم با استفاده از مدل ویکور بررسی شد. نتایج حاکی از آن است که محدودیت های توپوگرافی و در راس آن ها شیب زیاد، دره های یالی، آبراهه ها و مخاطره زمین لغزش مهم ترین موانع در راه توسعه فیزیکی پایدار شهر پاوه هست. پهنه بندی مخاطره زمین لغزش نشان داد که بیش از 43 کیلومتر مربع از منطقه مورد مطالعه در محدوده خطر زیاد واقع شده است و این در حالی است که 41 درصد از سطح کنونی شهر پاوه بر روی مناطق ناپایدار واقع شده است. شیب زیاد، وجود رسوبات منفصل و هوازده، نزدیکی به خطوط گسلی و جاده، توان بالای آبراهه و از بین رفتن پوشش گیاهی احتمال وقوع ناپایداری های دامنه ای را در بخش های شمالی شهر پاوه، دامنه شرقی دوریسان و نوریاب افزایش داده است. تخطی از مقررات ساخت و ساز شهری و خروج فرایندهای ساخت و توسعه از قیود برنامه ریزی شهری، مانعی برای تحقق توسعه پایدار شهری در پاوه خواهد بود و در نتیجه ضریب ریسک مخاطرات دامنه ای را در این منطقه بالا برده است.
کلید واژگان: توسعه شهری, مخاطرات ژئومورفیک, نقشه های ژئومورفولوژی, زمین لغزشIntroductionAnthropogenic impacts on the natural environment can lead to interference and increase vulnerability in the landscape and affect ecosystem services, environmental health and environmental sustainability. Increasing knowledge of the interconnected nature of many human and environmental issues has encouraged natural scientists (such as hydrologists, geomorphologists, and physical geographers more broadly) to work with social scientists (such as economists and human geographers) and engineers (such as designers). Environment, city planners) and policymakers to create an integrated interdisciplinary framework to meet new research needs. Urban geomorphology is an interdisciplinary field which is rapidly evolving and examines the effects (positive and negative; direct and indirect) of urbanization on the natural forms of the earth (geomorphology) and man-made structures (urban morphology), the processes that control their development in a given region. The city of Paveh is a vital human center in western Iran, located in the mountainous region of Shahu in the northwest of Kermanshah province, 20 km from the international border of Iraq at an altitude of 1600 meters. This study aims to evaluate the capacities and bottlenecks of sustainable urban development in Paveh city with the approach of geomorphological hazards. The ultimate goal of this study is to improve geomorphological awareness in order to understand the interaction between landforms, urban evolution and effective geomorphological processes, as a first step towards risk management and strategic protection of Paveh urban center.
Material and methodsThe present study is an applied research. In this study to evaluate and zoning landslide risk 12 variables affecting the occurrence of this geomorphological phenomenon including altitude, slope, aspect, lithology, land use, stream power index, topographic wetness index, topographic position index, distance from fault lines, distance from hazardous road points, normalized vegetation index and land curvature were examined. The required data were obtained from 1: 100000 scale geological maps, images of digital elevation model of the region with a resolution of 12.5 meters related to ALOS-PALSAR satellite, hydrological data and field studies as well as library resources. Geomorphological map of the region was drawn using field studies and satellite images. To prepare thematic layers and implement research models, Arc GIS, ENVI and Surfer software were used. VIKOR method was used to zoning and spatial prediction of landslide occurrence.
Results and discussionCurrently, the city of Paveh is facing problems and issues such as increasing population, reducing geomorphic potencial, increasing the load on the slopes, all of which confirm that the natural bed of the city of Paveh is more unstable. Most residential areas in the region are located on the slope unit. Changes in geomorphic units have caused changes in other loops of natural systems and ultimately altered the dynamics and morphogenesis of the city. Based on field studies and geomorphological map of the study area, the most important hazards threatening the sustainable urban development of Paveh can be listed as follows:Topographic restrictions and urban development of Paveh, Changing the natural cover of the earth and changing geomorphological trends, urban decay problems against environmental hazards, Urban construction weight and geomorphological changes, Non-standard slopes and creating limits to sustainable urban development, Sliding vulnerabilities of settlements and landslide hazard. The geomorphological map of the study area shows the presence of talus slopes in the northern parts of the region, which are the result of high temperature fluctuations in the Biston limestone formation. Several landslides have occurred in the southern parts of the region (Ilam Formation) and the northern slopes of Dourisan as a result of high slopes and possibly heavy rainfall events. Ridge valleys are one of the most important limitations of development in the northern parts of Paveh, Nouriab and Dourisan basins. A clear example of the ridge valleys can be seen in the neighborhood of the Grand Mosque, which has caused the destruction of urban uses, especially the asphalt and paving surfaces of the alleys. By examining the slip risk classes in the study area and comparing them, it can be seen that the areas where there are high and very high risk classes are on slopes above 40%;. The sensitivity of geological formations to degradation and weathering has caused the accumulation of large volumes of material on the slopes with other conditions (creating roads and fragmentation of slopes and heavy rainfall) may cause many landslides. In the northwestern part of Dourisan basin, due to severe temperature fluctuations, favorable conditions have been provided for landslides and rockfall. Landslides with a high probability of landslides are seen as relatively large spots. Excavation and trenching on Shahu Road, the presence of locally aerated and detached formations and slopes of 35 to 65 degrees can lead to local instabilities in this area. Due to the high probability of occurrence of Mass wasting hazard in Paveh, the amount of suitable land for the future development of the city is very small.
ConclusionDue to the increasing physical development of Paveh city and the general tendency to settle in foothills in the future, human activities will play an effective role in the occurrence of geomorphological hazards. Based on the findings of the research, urban development in Paveh is moving with the destruction of garden and agricultural lands and moving towards unstable lands (slope of more than 35%). Landslide hazard map showed that the high-risk zone covers more than 40 square kilometers (43%) of the study area. Therefore, the current bed of the city of Paveh is at risk due to extensive processes, so that 39% of the area of the city is located in high-risk landslides. With the development of Paveh towards areas with high slope gradients, especially in the northern and eastern parts, the new settlements will be completely in the high-risk area of landslides.
Keywords: Urban Development, geomorphic hazards, geomorphological maps, Landslides -
رشد شهرها و تاثیرات حاصل از آن بر محیط پیرامون، پیامدهای زیان باری به دنبال دارد؛ اما با شناخت و آگاهی از نواحی، بررسی، به کارگیری و استفاده بهینه از علوم و فناوری های جدید می توان به سمت توسعه پایدار حرکت کرد؛ از سویی جغرافیا و شاخص های بسیار مهم آن به ویژه ژئومورفولوژی به مثابه علمی تخصصی و کاربردی، نقش موثری در رشد و گسترش مراکز شهری دارد. در پژوهش حاضر، وضعیت توسعه شهر و مخاطراتی بررسی شده است که بر این توسعه تاثیر می گذارد. در این پژوهش با استفاده از قابلیت تکنیک سنجش از دور و سیستم اطلاعات جغرافیایی، تغییرات کاربری اراضی شهر قائن به منظور تخمین افزایش سطح مجموعه شهری و میزان کاهش اراضی کشاورزی و باغی در بازه زمانی سال های 2000 تا 2017 بررسی شد؛ همچنین تاثیر آن بر مخاطرات ژئومورفولوژیکی ازجمله گسل، آبراهه و لیتولوژی در منطقه ارزیابی شد. در ادامه محدوده کاربری با الگوریتم حداکثر مشابهت، روش نظارت شده و مدل زنجیره مارکوف در افق 1404 مشخص شد. نتایج پژوهش حاضر نشان می دهد طی سال های 1379، 1389 و 1396 مساحت کاربری محدوده های ساخته شده در شهر قائن افزایش داشته و این افزایش سبب نزدیک شدن شهر به سازندهای رسی، گسل ها و آبراهه اصلی شده است؛ به طوری که مساحت اراضی ساخته شده (84/114درصد)، باغ ها و زمین های کشاورزی (1/99درصد)، زمین های بایر (71/99درصد) و مراتع (94/99درصد) تغییر خواهد کرد. تلفیق داده های متفاوت برای به دست آوردن نتایج دقیق تر و منسجم تر و همچنین آینده نگری برای شناسایی مناطق مساعد به منظور رشد و گسترش شهری در سال های آتی، نوآوری این پژوهش محسوب می شود.کلید واژگان: تصاویر ماهواره ای, تغییرات کاربری اراضی, مدل زنجیره مارکوف, مخاطرات ژئومورفیک, قائنThe growth of cities and their impacts on the environment have disastrous consequences. But, with having the knowledge of the areas, investigation, employment, and proper use of new technologies, sustainable development can be achieved. On the other hand, geography and its most important indicators, especially geomorphology as a specialized science, can play an important role in the growth and development of urban centers. The present study examines the development status of the city and the risks that affect its development. In the present study, using the remote sensing and geographic information system of land use changes in the city of Qaen, in order to estimate the increase in the urban area and the reduction of agricultural and horticultural lands in the period from 2000 and 2017, and also its effect on the geomorphological hazards (such as fault, waterway and lithology) has been studied in the region. The area of use was characterized by maximum similarity algorithm, supervised method and Markov chain model at 1404 horizons. The results of this study show that during the years 2000, 2010 and 2017, the area of use of the boundaries built in the city of Qaen has increased and this increase has brought the city closer to the clay formations, faults and main waterways. So that constructed lands (114.84%), gardens and agricultural lands (99.1%), uncultivated lands (99.71%) and rangeland (99.94%) will change. The combination of different data to obtain more accurate and coherent outcomes as well as a vision for identification of favorable areas for urban growth and development in the coming years will be considered as the innovation of this research.Keywords: satellite images, land use changes, Markov chain model, geomorphic hazards, Qaen
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ایران جزو 10 کشور اول مستعد وقوع مخاطرات طبیعی دنیا است. ازجمله راهکارهای اساسی به عنوان ابزاری کار آمد در جهت کاستن از مخاطرات فوق، شناسایی عوامل دخیل در ایجاد مخاطرات و پهنه بندی میزان خطر است. پژوهش حاضر نیز برای دست یافتن به چنین هدفی به بررسی مخاطرات ژئومورفولوژیک آبی - بادی بر روی جاده شهداد- نهبندان واقع در شمال غرب میراث جهانی لوت پرداخته است. در این راستا ابتدا به صورت میدانی نقاط مخاطره آمیز شناسایی و به کمک جی پی اس مارک شد. سپس عوامل موثر در وقوع مخاطرات مورد نظر شناسایی و به کمک مجوعه فازی و اخذ نظر کارشناسان وزن دهی شده و لایه ها با استفاده از مدل تحلیل شبکه ای همپوشانی شد. نتایج حاصل از تحلیل پهنه بندی خطر نشان داد که حدود219 کیلومتر از طول جاده دارای خطر متوسط تا خیلی زیاد از نظر سیلاب و 252 کیلومتر از طول مسیر در پهنه خطر متوسط تا خیلی زیاد حرکت ماسه های روان واقع شده است. که این امر توجه به برنامه ریزی و مطالعات محیطی در محور ارتباطی ذکر شده به عنوان یکی از مهمترین محور های مواصلاتی در جهت دست یابی به میراث جهانی لوت و عوارض چشم نواز ژئومورفولوژیکی آن است را به خوبی آشکار می سازد.
کلید واژگان: مخاطرات ژئومورفیک, پهنه بندی, محور شهداد- نهبندان, لوتIran is one of the top 10 countries facing natural hazards in the world. One of the basic approaches is to reduce the above-mentioned hazards, to identify the factors involved in hazard and risk zoning. The present study also explores the geomorphologic hydro-wind hazards on the Shahdad-Nehbandan road northwest of the Lut World Heritage, in order to achieve such a goal. In this way, the field was first identified with hazardous points and was marketed with the help of GPS. Then, the effective factors in the occurrence of the desired hazards were identified and the experts were weighed using the fuzzy set and the layers were overlaid using the ANP model. The results of the flood hazard zonation analysis showed that about 219 km of road length is moderate to very high, and the sand-zone hazard map illustrates the fact that more than 252 km of roads are exposed to windblown hazards. This fact highlights the emphasis on planning and environmental studies in the communication axis as one of the most important axes for achieving the Lut World Heritage and its eye-catching geomorphologic complications.
Keywords: geomorphic hazards, zoning, Shahdad-Nehbandan axis, Lut -
مخاطرات زمینی و ژئومورفیک از مخاطرات مهم طبیعی اند که سالیانه خسارات جانی و مالی زیادی در کل کشورهای جهان و به ویژه ایران به بار می آورند. از این رو، مطالعه و تهیه نقشه پهنه بندی مخاطرات امروزه یکی از اولویتهای هر کشور به شمار می آید. در این تحقیق به بررسی مخاطرات زمین لغزش و سیل در سطح استان البرز پرداخته شده است. برای تهیه نقشه پهنه بندی خطر زمین لغزش استان، از مدل ترکیبی VIKOR-AHP و برای تهیه نقشه پهنه بندی خطر سیل از مدل نسبت فراوانی FR استفاده شد. سپس، به منظور داشتن دیدی کلی و جامع نسبت به وضعیت این مخاطرات، نقشه تلفیقی مخاطرات استان، که از همپوشانی دو نقشه پهنه بندی سیل و زمین لغزش است، با استفاده از مدل FUZZY تهیه شد. طبق نتایج نهایی حاصل از نقشه های پهنه بندی هر یک از مخاطرات، 09/33درصد سطح استان در پهنه با خطر زیاد زمین لغزش و 21/21درصد از سطح استان در پهنه خطر متوسط سیل قرار دارند که شناسایی و پهنه بندی مناطق دارای پتانسیل خطر وقوع اینگونه مخاطرات اهمیت بسیاری دارد.کلید واژگان: استان البرز, مخاطرات ژئومورفیک, مدل نسبت فراوانی, مدل VIKOR-AHPIntroduction Natural hazards with their varieties and their extent of influence as repetitive and destructive phenomena have always been present through the life in the planet; they have always been a serious threat to human beings since the advent of mankind. Accordingly, it can be said that no community claims immunity from natural hazards, and humans always suffer from objective and subjective harmful effects. Natural hazards by destroying income sources, biological resources, and people activity centers (houses, workshops, farms, etc.), increase their economic and physical harms. Related to the history of the hazards studies, the following notes could be mentioned. Materials and Methods In this research, in order to zone the flood and landslide hazards in the Alborz Province based on the used models, the indices of each model were extracted to be utilized in providing the risk map of these hazards as follows: for the landslide hazard zonation of the Alborz Province, one of the outranking methods, entitled VIKOR consensus optimization method, based on calculation of maximum utility and minimum losses was utilized and the susceptibility map of the sub-basins of the Alborz Province was prepared according to the occurrence of the landslide phenomenon. IN order to study the flood hazard of the Alborz Province, the Frequency Ratio Model (FR) was used. In order to perform these two models, it is necessary to extract the most important indices affecting the occurrence of the hazards; for this purpose, based on a deep investigation on previous studies in this field as well as the features of the study area, 9 indices were determined for landslide zoning using VIKOR-AHP compound model as follow: lithology, drainage density, soil type, precipitation, altitude, distance from the fault, land use, dip gradient, vegetation As well, for the flood zoning, using the frequency ratio model, 11 indices were applied which are: lithological factors, land use, distance from the river, soil type, dip gradient, dip direction, surface curvature map, Topographic Wetness Index (TWI), drainage density, altitude and amount of precipitation. Discussion and results In order to zone the risk of the landslide in the Alborz Province, initially nine criteria were considered regarding the basin tendency to land-sliding in sub-basins. After selecting the main criteria, in the next stage, the maps for each one of the selected criteria for weighting and evaluating sub-basins in the GIS environment were prepared and mapped. Considering the effect of the nine criteria in the occurrence of landslide (distance from fault, precipitation, vegetation, land use, soil type, lithology, height, drainage density and dip) distance from fault and vegetation criteria have a decreasing effect and the other seven criteria have an increasing effect. After preparing the selected criteria map, the significance coefficient of the mentioned criteria was determined by the AHP hierarchical algorithm, based on the importance level of the landslide occurrence and basins susceptibility to this phenomenon. In this investigation, in order to weight options based on the role of each criterion in the considered option, the definitive weighting range of one to ten is used; so that weight 1 has the least effect and weight 10 indicates the most effect in the landslide risk. After determining the importance coefficient of the criteria, weights decision matrix was prepared for the VIKOR algorithm. As it is known, nine criteria are efficacious in evaluation of the watershed basins. Table 2 shows the decision matrix based on the effective parameters in the sub-basins. After weighting and preparing the weight matrix, the matrix values were normalized. Conclusion The results of the landslide study in the Alborz Province indicates that in Taleghan and Karaj counties, the occurrence possibility of landslide is high due to the natural conditions of the region in terms of considered indices; since in these counties, the precipitation conditions are relatively good and vegetation is mainly of poor pasture type, there are no proper drainage conditions. The presence of less developed soils and almost impermeable bedrock, high altitude and relatively steep slope in these areas and the presence of frequent faults, provided the occurrence condition of landslide phenomenon. Therefore, as the output of the landslide zoning map shows, more than 60% of the area of these two counties are located in high-risk areas. Also, the natural conditions in relation to the flood risk is persistent and some indices such as susceptibility to erosion, land use, rivers distance, amount of precipitation, altitude, precipitation, slope angle and slope direction have led to the presence of possibility of flooding in the Alborz Province; consequently, due to the dominance of these indices in Taleghan, Karaj and Savojbolagh counties, the highest flood risk could be observed respectively. The situation of Taleghan and Karaj counties are more susceptible and vulnerable to geomorphic hazards; because the area percentage of the high and high risk classes in these two counties is considerable (high). On the other hand, most of the habitat areas of the Province are situated in high risk places in terms of flood and landslide hazards; it shows the necessities of more detailed planning to prevent the hazards and the related damages. In the following, in order to investigate the status of residential centers of the Alborz Province in relation to geomorphic hazards and the degree of adaptation and correct location-defining of these centers (urban and rural), a study was conducted; it indicates the establishment of most urban and rural centers in high-risk areas. For example, 52% of the Karaj County with 28% of the Province’s area and about 2 million populations are located in very high flood and landslide risk zones; in order to reduce their probable losses, people should be aware of probable risks and necessary plans should be considered.Keywords: Geomorphic hazards, Landslide, Flood, VIKOR-AHP, Fr model Alborz province
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امروزه شهرها، در نقاط مختلف دنیا به دلایل متعدد در معرض آسیب ناشی از مخاطرات طبیعی قرار دارند، این مخاطرات که آسیب های جانی و مالی بسیاری با خود به همراه دارند نیازمند اقدامات فوری و پیشگیرانه می باشند. بر مبنای برنامه استراتژیک بین المللی کاهش بلایای سازمان ملل متحد، کلیه مخاطرات دارای دو منشا طبیعی و فعالیت های انسانی می باشد. استان گیلان یکی از استان های ساحلی شمال ایران به مرکزیت کلان شهر رشت می باشد. هدف از پژوهش حاضر تحلیل و پهنه بندی مخاطرات ژئومورفیک در استان گیلان م یباشد. روش انجام این تحقیق به دو صورت توصیفی - تحلیلی و تجربی است که در بخش توصیفی با استفاده از مطالعات اسنادی و در بخش تحلیلی نیز با شناسایی پارامترهای موثر در پهنه بندی مخاطرات ژئومورفیک و تلفیق آن با تحلیل های فضایی در سیستم اطلاعات جغرافیایی (GIS) پهنه های آسیب پذیر در محدوده مورد مطالعه مشخص گردید. در این پژوهش ابتدا عوامل موثر در پهنه بندی مخاطرات شناسایی شدند. سپس به منظور سنجش میزان اهمیت هر یک از این عوامل، پرسشنامه ای تدوین شد تا با روش ANPو با اخذ نظرات کارشناسان مربوطه در زمینه هر یک از عوامل شناسایی شده، بتوان به اهداف پژوهش دست یافت. پس از اخذ نظرات و با استفاده از روش منطق فازی به ارزش گذاری هریک از معیارها و تعیین ضرایب اهمیت آنها پرداخته شد و بر اساس نتایج آن، ارزیابی فضایی با استفاده از نرم افزارARC GISصورت گرفت و پهنه های پرمخاطره مشخص گردید. نتایج نشان داده است که به کارگیری منطق فازی به همراه تحلیل فضاییGIS توانسته است به عنوان ابزاری کارآمد در پهنه بندی مخاطرات ژئومورفیک مورد استفاده قرار گیرد و به خوبی قابلیت و توانایی مدل تحلیلی پژوهش را به اثبات برساند.کلید واژگان: مخاطرات ژئومورفیک, امنیت, تحلیل فضایی, منطق فازی, استان گیلانIntroductionToday, cities in different parts of the worldare exposed to damages from natural hazards for various reasons. These hazards which are associated with lots of financial damages, fatalities and injuries, are in need for urgent preventive measures. Based on the United Nation International Strategic Plan for disaster reduction (UNISDR), all hazards have two natural and human activities origins.The province of Gilanis one of the northern coastal provinces, whose center is the city of Rasht. The objective of the present research is, analyzing and zoning geomorphic hazards in the province of Gilan. The method of this research is descriptive – analytical, and empirical. In the descriptive section, by using documentary studies and also in the analytical section, by identifying the effective parameters in the zonation of geomorphic hazards and integratingthem with the spatial analyses in GIS, vulnerable zones were identified in the study area.
In this research, the factors effective in the zonation of hazards were identified first. Then, in order to measure the significance of each of these factors, a questionnaire was prepared to carry out this important task by the method of ANP and by collecting the opinions of the relevant experts on each of the identified factors. After obtaining the opinions and using the fuzzy logic method, evaluation of each of the criteria and determination of their importance coefficients were done and based on its results, spatial evaluation was carried out using ARC GIS and high risks zones were identified.Results have shown that the use of fuzzy logic along with spatial analysis of GIS has been able to be used as an efficient tool in zoning geomorphic hazards and to prove the capability of the analytical model of research well.Materials & MethodsThe performing method of this research is descriptive-analytical, which is compiled using documentary studies of required information and dat. In this study, it was attempted to investigate the geomorphic hazards in the province of Gilan. At first, the study area was identified. In the next stage, information layers such as slope, topography, vegetation, the elevation map of land use and… were prepared using 1: 50000 topographic maps, 1:100000 and 1: 250000 geological maps, and Digital Elevation Model (DEM), and finally, the provided effective information layers by the experts’ opinion and the obtained field and documentary studies were investigated in the form of network analysis model. Network Analysis Process (ANP) is one of the techniques for decision-making. When several indicators are considered for evaluation, the evaluation task becomes complicated, and when the criteria are of different genders, the work will become more complicated, and the evaluation and comparison go out of the analytical state which the mind is capable of performing), and a strong tool for practical analysis is needed. Therefore, the network analysis process is capable of doing this (Shadfar et al., 2007: 66). The network analysis process is one of the multi-criteria decision-making techniques. This model has been designed based on the hierarchical analysis process and replaces ‘network’ with ‘hierarchy’. The main assumption in AHP is based on the independent function of the hierarchical upper groups from all of its lower parts and from the criteria of each level and class (Chang et al., 2005: 22 and De Seun, 2004: 636).Saatyhas proposed the use of the hierarchical analysis model (AHP) to solve problems with independent and dependent criteria and solutions, and has established and presented the network analysis model (Lee and Kim, 2001: 374). Thus, the ANP method was presented as an extension of AHP.
As the AHP provides a framework for hierarchical structures with one-way relationships, the ANP also provides the possibility of complex internal relationships between different levels of decision and criteria. The ANP feedback approach has replaced the network structure with hierarchical structure, suggesting that the relations between different levels of decision-making can’t simply be imagined as up-down, dominant-recessive or direct-indirect.In general, the ANP model consists of a hierarchy of control, clusters, elements, interrelationships between clusters and elements (Sarkis, 2002; 23; Oraet et al., 2006: 247). The geomorphic hazards of Gilan province were evaluated and zoned in 6 stages (Saaty, 1392).
1- First step:At first, given the field and library studies as well as the experts of the issue, the research-related elements were defined from 4 clusters with 11 elements. The relations between the variables and clusters were determined using correlation analysis.
2- Second step: the pairwise comparison matrix and the relative weight estimation: the determination of relative weightin ANP is similar to AHP, In other words, the relative weight of the criteria and the sub-criteria can be determined throughpairwisecomparison.Pairwise comparisons of the elements in each level are done similar to the AHP method because of its relative significance to the criterion of control.
3- Third step:the formation of primary super matrix. The ANP elements interact with each other. These elements can be the decision-making unit, criteria, sub-criteria, the obtained results, options, and anything else. The relative weight of each matrix is calculated based on the pairwise comparison similar to the AHP method. The resulting weights are entered in the super matrix, which indicate the mutual relationbetween the elements of the system.
4- Fourth step: the formation of a weight super matrix: super matrix columns consist of several special vectors that the sum of each vectoris equal to 1. Therefore, it is possible that the sum of each column of primary super matrixto be more than 1. In order to factorize the column elements proportional to the relative weight, and that the sum of the column be equal to 1, each column of the matrix is standardized. As a result, a new matrix is obtained, the sum of each column of which will be equal to 1. The new matrix is called the weight matrix. (FarajiShabbarbar et al., 2011: 56).
5- Fifth step:the calculation of the general weight vector: in the next step, the weight super matrix reaches to a power limit so that the matrix elements are converged and its row values are equal. The general weight vector is determined based on the matrix obtained.
6- Sixth step:the calculation of the final weight of the criteria: finally, the weight of each of the effective criteria is obtained. After determining the structure of the model and determining the weight super-matrices and the limit, the weight of each of the effective indices is obtained. After weighting the natural criteria effective in the zonation of the effective indices, using fuzzy logic technique in this stage, the maps of geomorphic hazards mapping of Gilan province are plotted
Results & Discussion: After determining the relationship between the effective criteria in geomorphic hazards, the experts’ opinions, the matrix of pairwise comparison, and the relative weight estimation, the formation of primary super matrix, the formation of weight super matrix, the calculation of the general weight vector, the calculation of the final weight of the criteria was carried out, using the mathematical operations in the ArcGissoftware. Then, using fuzzy logic technique, maps of geomorphic hazards zonation in Gilan province were drawn. Given the combination of all layers and the application of the coefficients obtained from the network analysis model, the final map of geomorphic hazard zonation was plottedand three vulnerable zones were obtained.
1- First zone - Northeast of the province: This is a zonewith high risks due to its location on the way of floods and geological features.
2-Second zone: south of the province: located in the vicinity of Roodbar and Rudsar, and to some extent Amlash, is considered as a part of high risky zones of the province. Closeness to the faultand relatively high slope are among the characteristics of this zone.
3-Third zone: center of the province: in the vicinity of the city of Bandar-e Anzali, Somesara is considered as high risk zones of the province. Flooding, high erosion, and slope movements to some extent are among the features of this zone.ConclusionInvestigating the situation and the value of vulnerable human environments against various types of geomorphological hazards seems to be very important and essential. Natural hazards, especially geomorphic hazards, have already had and have lots of financial and losses and fatalities. On this basis, natural hazards were considered as one of the basic studies in order to be able to control and reduce natural hazards. Thus, the most risky zones of Gilan province were integrated into critical centers such as mines in the province. In order to model and predict the relative risk of geomorphic hazards in the present research, an ANP network analysis model was used. For each of the different values and ranges, a weight and score were obtained, for which the fuzzy sum of these scores and the integration of each layer in the obtained weight, determined the relative risk of the occurrence of geomorphic hazards. The results showed that three vulnerable zones in the northeast, south of the province I the vicinity of the cities of Roodbar and Rudsar, and to some extent,Amlash, and the center of the province in the vicinity of the cities of Bandar-Anzali, and Somesara, are risky and hazardous areas which are affected by the risks of flood and Geological features, proximity to faults and relatively high slopes, flooding, high erosion and, to some extent, movements of the slopes. The application of fuzzy logic along with spatial analysis of GIS has been able to be used as an effective tool forgeomorphic hazards zoning. In the end, it is necessary to note that the location of some of the zones at low levels of vulnerability and risk does not represent their idealsituation and determines only the place of the aforementioned zone in relation to other zones.Keywords: Geomorphic hazards, Safety, Spatial analysis, Fuzzy logic, Gilan -
انسان از ابتدای حیات خود دائما با تهدید های ژئومورفیک مواجه بوده و این مخاطرات، خسارات جانی و مالی را در زیستگاه های انسانی و به ویژه در شهر ها برای جوامع انسانی به دنبال داشته است. امروزه شهرها در نقاط مختلف دنیا به دلایل متعدد در معرض آسیب ناشی از مخاطرات ژئومورفیک قرار دارند، که شهرهای استان لرستان واقع در رشته کوه های زاگرس نیز از این قضیه مستثنی نیستند. هدف از این تحقیق پهنه بندی و شناسایی پهنه های پرخطر ژئومورفیک در مناطق شهری استان لرستان با استفاده از روش توصیفی- تحلیل و تجربی می باشد. در روش توصیفی داده ها و اطلاعات مورد نیاز از منابع و سازمان های مختلف تهیه شد. در روش تحلیلی عوامل موثر در پهنه بندی مخاطرات ژئومورفیک زلزله، سیل، زمین لغزش و روانگرایی و تلفیق آنها جهت تهیه نقشه مخاطرات ژئومورفیک با استفاده از تحلیل های مکانی GIS و مدل های AHP و منطق فازی انجام گرفت. ابتدا پارامترهای موثر در رخداد هر یک از مخاطرات شناسایی و پس از استانداردسازی پارامترها با استفاده از توابع کاهشی و افزایشی منطق فازی و وزن دهی به پارامترها با استفاده از تحلیل سلسله مراتبی، پهنه های پرخطر در شهرها شناسایی شد. نتایج نشان داد که اکثر شهرهای استان لرستان به دلیل عبور رودخانه های اصلی از محدوده شهرها، در معرض خطر سیلاب قرار دارند. هم چنین مشخص شد که شهرهای واقع در غرب استان در معرض خطر سیلاب و شهرهای شرق استان در معرض خطر زلزله و رخدادهای ژئومورفیک ناشی از زلزله مانند زمین لغزش و روانگرایی قرار دارند.کلید واژگان: مخاطرات ژئومورفیک, زیستگاه های شهری, سیلاب, زلزله, استان لرستانNatural hazards are basically the changes that occur in environmental conditions, causing a disruption of the natural life of the people and their exposure to hazardous and degradable elements and elements. Establishing cities and residential areas on landforms has created new perspectives. The development of these areas has altered the geostationary balance of many landforms, and the response of geosystems is an expression of geomorphological hazards such as land subsidence, fault activity, flood, and the like that threatens residents of urban areas. The trend of population growth in the urban areas of Lorestan province in western Iran has also caused the physical expansion of the provincial cities in the periphery. This development has resulted in landslides and areas that, in many cases, have not been studied in environmental and environmental sustainability. The consequence of this is to increase the risk factor of these areas against a variety of hazards. In this regard, the aim of this study is to analyze the geomorphic hazards of earthquake, flood, landslide and liquefaction in the 9 major cities of the province and zonation of areas based on the degree of risk, in order to identify the high risk areas, urban management, necessary measures to increase environmental capabilities. And reduce vulnerabilities
In this research, effective factors were first identified in the occurrence of each of the flood geomorphic hazards, landslide, earthquake and fluidization. Then, maps were prepared for each of the factors, topographic maps, geology, geological data, seismicity, etc. from different organizations and maps were prepared. After preparing the maps, the fuzzy standardization method (decreasing and incremental functions) was used to determine the effective impact of each of the effective information layers in the occurrence of each of the hazards. In the final stage, considering the factors affecting the occurrence of any geomorphic hazards, weighing to layers based on their degree of importance was carried out using (AHP) method. At this stage, the final weight of each layer was multiplied in the corresponding layer, and then together and the final map of each of the geomorphic hazards was prepared. After mapping each of the geomorphic hazards of the studied cities, weighing and combining earthquake, flood, landslide and fluidization layers, maps of geomorphic maps of the cities were prepared.
The study of the geomorphic hazards of the city of Poldokhtar in the south of the province suggests that flood occurrence is considered as the most important threat to the geomorphic city of Poldokhtar. There is also a possibility of liquefaction due to the high groundwater level, especially in the north of the city. In the city of Kohdasht, in the west of the province, the risk of flood events is higher than the other hazards due to the river passing as a drainage of the catchment from the city. Geomorphic hazards in the northern city of northern Lorestan indicate that the central part of the city is at risk of landslide and liquefaction and parts of the north, west and south are exposed to flood. The probability of occurrence of geomorphic hazards in the area of Alshatr in the north of Lorestan province is low. So that the northwest and eastern parts of the city are risk free and in other parts, the risk of geomorphic hazards is moderate and low. Surveying the risks of Boroujerd city indicates that parts of the West of the city that are in high risk of flood, landslide and liquefaction are known as high risk areas and southern regions as low risk areas. Also, among the threats of Borujerd city, the probability of an earthquake due to the crossing of the young Zagros fault from the Silakhor plain is more than the other geomorphic hazards. In the city of Azna, the risk of flooding is considered to be the most significant danger to the city, although there is a likelihood of landslide and fluidization. The study of geomorphic hazards in the city of Aligudarz shows that rivers in the west of the city are exposed to geomorphic hazards, especially flood. In the city of Dorood, the flood event seems more likely than other hazards. The flood event in the central part of the city, which crosses the main rivers, has the highest potential. But in general, the risk of an earthquake is the most important geopolitical risk in the city of Dorood. In the city of Khorramabad as the capital of Lorestan province, the southern parts of the city have the highest geomorphic risk due to the high potential of flood and liquefaction. Also, the flood risk is considered to be the most important geomorphic risk in the city.
The study of geomorphic hazards in the major cities of Lorestan province suggests that there is a probability of occurrence of hazards in urban areas, but the types of hazards are different in cities located in the west and east of the province. Studies show that there is a potential for flood events in many cities, especially in southern cities and Khorramabad, in the capital of the province. Cities located in the east of the province (Doroud, Azna and Boroujerd) have a high density of earthquake occurrence due to the fact that they are located in the zone of the young Zagros fault and the Seychelles seismic quake. Nevertheless, according to geological formations, there is a possibility of landslide occurrence in the cities of Khorramabad and Aligudarz. The likelihood of occurrence of liquefaction occurrence in the studied cities is higher, especially in the eastern province of the province, because the urban areas are mainly located in plains with high groundwater and alluvial soils. The final results show that the risk of flood in the western regions of Lorestan province and the earthquake in the eastern provinces of the province are the most important threats to geomorphic cities.Keywords: Geomorphic hazards, Lorestan, urban bio-complexes
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