پهنه‌بندي خطر مخاطرات طبيعي در مناطق روستايي با استفاده از سيستم اطلاعات جغرافيايي با تاكيد بر فاكتور زمين‌لغزش (مطالعه موردي: دهستان دو هزار شهرستان تنكابن)

Natural Disaster Risk Zoning in Rural Areas Using Gis with Emphasis on Landslides Factor (Case Study: Dohezar Dehestan of Tonekaon County)

هدف: به طور كلي هدف نهايي اين مقاله بررسي و مطالعه زمين‌لغزش‌ها در راستاي يافتن راه‌هاي كاهش خسارات ناشي از آن‌ها مي‌باشد كه همين امر لزوم تهيه نقشه پهنه‌بندي خطر زمين‌لغزش را ضرورت مي‌بخشد. روش: روش تحقيق در اين مقاله از نوع كاربردي و رويكرد حاكم بر آن تحليلي و كمي است و به‌منظور آماده‌سازي لايه‌ها در سامانه اطلاعات جغرافيايي، از 10 لايه اطلاعاتي شامل: نقشه‌هاي شيب، جهات جغرافيايي شيب، بارش، زمين‌شناسي، فاصله از گسل، عامل انساني، لايه خاك به همراه ويژگي‌هاي فيزيكي و شيميايي آن شامل: غلظت آهك، نمك (هدايت الكتريكي) و ph استفاده گرديد. همچنين جهت پهنه‌بندي خطر وقوع زمين‌لغزش از روش بينا و مدل ارزش اطلاعاتي در محيط GIS استفاده شده است. يافته‌ها: نتايج نشان مي‌دهد 88/25 كيلومترمربع از كل دهستان موردمطالعه، داراي پتانسيل خطر خيلي كم، 09/54 كيلومترمربع، خطر كم،57/92 كيلومترمربع، خطر متوسط، 57/85 كيلومترمربع، خطر زياد و 50/34 كيلومترمربع داراي پتانسيل خطر خيلي زياد در دهستان دو هزار در شهرستان تنكابن مي‌باشد كه در اين خصوص عامل انساني به‌عنوان عامل اصلي در اين رابطه محسوب مي‌شود و با توجه به مطالعات انجام شده 13 روستا با جمعيت 7517 نفر در پهنه خطر خيلي كم، 15 روستا با جمعيت 5595 نفر در پهنه خطر كم، 33 روستا با جمعيت 15488 نفر در پهنه خطر متوسط، 26 روستا با جمعيت 9640 نفر در محدوده خطر زياد و 16 روستا با جمعيت 5187 نفر در پهنه خطر خيلي زياد قرار دارند. محدوديت‌ها/ راهبردها: زمين‌لغزش‌ها رخدادهاي طبيعي بوده كه تحت تاثير عوامل مختلف باعث ايجاد خسارت به مناظر طبيعي، انسان‌ها و تاسيسات مي‌شود. ازآنجاكه پيش‌بيني زمان رخداد زمين‌لغزش‌ها از توان علم و دانش فعلي بشر خارج مي‌باشد، لذا با شناسايي مناطق حساس به زمين‌لغزش و رتبه‌بندي آن مي‌توان تا حدودي خطرات ناشي از وقوع زمين‌لغزش را جلوگيري نمود، لذا پايش مداوم مناطق حساس به زمين‌لغزش و رتبه‌بندي آن‌ها به‌عنوان راهبردي كارآمد در فرآيند مديريت بحران توصيه مي‌گردد. راهكارهاي عملي:انتظار مي رود با شناسايي مناطق با پتانسيل بالاي زمين لغزش از يك طرف مكان يابي روستاهاي جديد با دقت بيشتر انجام شود و از طرف ديگر جهت بهسازي و بهبود كيفيت كالبدي روستاهاي قرار گرفته در پهنه هاي پرخطر تصميمات جدي اتخاذ گردد. اصالت و ارزش: انتظار مي‌رود نتايج اين تحقيق ضمن افزودن بر غناي ادبيات موضوع، مسيولين ذي‌ربط را نيز در اتخاذ تصميمات بهينه مديريت بحران در مناطق مستعد زمين‌لغزش رهنمون باشد.

1. INTRODUCTION Scientific study of landslide phenomena is one of the most important issues in the world for various reasons. In Iran, there are three areas prone to earthquakes, including Zagros, Alborz, and central parts of Iran. Lack of certainty that comes from vague, incomplete, and ambiguous terms and concepts related to characteristics such as geology, hydrology, tectonic, vegetation, rainfall, erosion, temperature variations, etc., has necessitated the need for an accurate and a convenient method of slope instability in the study of the earth. Since the prediction of landslide occurrence is beyond the current human knowledge, identifying areas vulnerable to landslides and ranking them, can, to some extent, prevent the risks of landslides. The emergence of various models and methods for the study of landslides mapped by geologists show that, globally, many studies have been done on the risks of landslides. 2. METHODOLOGY This study is a practical and analytical approach to governing it. Two thousand city Tonekabon is a place territory of the district. In this paper, a library and field data collection and analysis of qualitative and quantitative data using statistical inference methods ArcGIS10 done using software. To prepare the GIS layers, 10 layers of information including slope maps, driving directions, slope, rainfall, geology, faults, human factors, physical and chemical soil layer with features including: concentration lime, salt (EC) and the ph was used. Also for landslide hazard zoning sighted approach and the value of the information (Winf) is used in GIS. 3. DISCUSSION Due to its geographical conditions and lack of comprehensive management and non-compliance with environmental thresholds, Iran is considered as a high risk country; thus, has been placed among the worldʹs 10 countries prone to natural disasters. With regard to the distribution of landslides occurred in the study area that is allocated to an area of about 0/108113 square kilometers and 5 point occurred, zoning landslide susceptibility in model.The results showed that, 25/88 square kilometers of the village studied has very low risk potential, 54.09 square kilometers has low risk, 92.57 square kilometers has moderate risk, 85.57 square kilometers has high risk, and 34.5 square kilometers has very high potential of risk with human factor as the main factor in this regard. The calculated results show that, there is a significant inverse relationship between the decrease in number and population of villages and being in danger zones. Correlation and significance level of risk associated with landslides, and the number and population of villages, indicated that there is a significant relationship between risk of landslides and number and population of villages. 4. CONCLUSION By identifying vulnerable areas and landslide zoning, decreasing slopes, establish an independent landslides research group, and most importantly, public education, especially to the residents of the surrounding areas vulnerable to landslides, to pay more attention to its injuries and reduce investment in the future, landslides in these areas can be prevented. In this regard, according to the p-value, there is a relationship between the two variables at a level greater than 0.01. Pearsonʹs test showed a significant and strong correlation between the risk of landslides, and the number and population of villages. According to studies, the following strategies to prevent this natural phenomenon include: operations to reduce groundwater, drainage, preventing water penetration, stabilizing gradient platforms, constructing retaining walls, preventing destruction of vegetation, and planting native plants, preventing the spread of residential areas, or in public places prone areas, especially in areas with a high risk zone before stabilizing.