شناسایی مناطق سیل زده و تحلیل عوامل موثر در وقوع آن (مطالعه موردی: جنوب شرق استان سیستان و بلوچستان) (مقاله علمی وزارت علوم)
درجه علمی: نشریه علمی (وزارت علوم)
آرشیو
چکیده
سیلاب از جمله مخاطراتی است که در طی سال های اخیر بارها در استان سیستان و بلوچستان، خصوصا مناطق جنوب شرقی آن رخ داده است. در واقع، این منطقه تحت تاثیر نوع بارش و همچنین وضعیت طبیعی، پتانسیل سیل خیزی بالایی دارد. با توجه به اهمیت موضوع، در این پژوهش به شناسایی مناطق سیل زده جنوب شرق استان سیستان وبلوچستان و تحلیل عوامل موثر در وقوع آن پرداخته شده است. در این تحقیق از تصاویر راداری سنتینل 1 و 2، تصاویر لندست 9 و مدل رقومی ارتفاعی 30 متر، به عنوان مهم ترین داده های تحقیق استفاده شده است. مهم ترین ابزارهای تحقیق، سامانه گوگل ارث انجین و ArcGIS بوده است. همچنین در این تحقیق از مدل منطق فازی جهت شناسایی مناطق آسیب پذیر در برابر مخاطره سیلاب استفاده شده است. این پژوهش در چند مرحله انجام شده است که در مرحله اول، مناطق سیل زده در طی سیلاب اسفند سال 1402 شناسایی شده است و در مراحل دوم و سوم به ترتیب به تحلیل عوامل موثر در وقوع سیلاب منطقه و شناسایی مناطق آسیب پذیر در برابر این مخاطره پرداخته شده است. بر اساس نتایج حاصله، مناطق جنوب شرقی شهرستان دشتیاری، بیش ترین میزان سیل زدگی را داشته است که در بین عوامل موثر (به جزء عوامل اقلیمی)، وضعیت ارتفاعی و شیب بیش ترین اثرگذاری را داشته است. همچنین در این پژوهش، مناطق آسیب پذیر در برابر مخاطره سیلاب شناسایی شده است. بر اساس نتایج حاصله، مناطق جنوبی محدوده مطالعاتی شامل بخش های میانی و جنوبی شهرستان دشتیاری، مناطق شرقی و جنوبی شهرستان چابهار و همچنین مناطق جنوبی شهرستان کنارک، دارای بالاترین پتانسیل سیل خیزی هستند. با توجه به نتایج حاصله، تحت تاثیر وضعیت طبیعی منطقه، بخش زیادی از این منطقه، در معرض مخاطره سیلاب قرار دارد که باید مورد توجه ویژه قرار گیرد.Identification of flooded areas and analysis of factors influencing its occurrence (Case study: Southeast of Sistan and Baluchestan province)
IntroductionOne of the challenges that many societies face is the occurrence of natural hazards. There are different types of natural hazards, and flood is one of the most important natural hazards, which is always associated with a lot of human and financial losses. In fact, floods are considered as one of the most destructive hazards that cause many human and financial losses every year, so that according to the report of the international database of hazards, floods along with earthquakes and droughts, have had the highest human and financial losses. Also, according to the statistics published in 2010, more than 40% of the natural disasters in the world are caused by floods. In recent years, due to the increasing trend of population and increase in human activities and misplaced human interventions in nature, the possibility of flood occurrence has increased and the risks caused by it have intensified. According to geomorphology, hydro climatic, land cover, etc., different areas have different potentials in terms of flood risk occurrence. Among the regions that have a high potential against flood risk are the southeastern regions of the country. These areas have a high potential against flood risk due to torrential rains, being located at high altitudes and low slopes, as well as poor vegetation, and this issue has caused many floods to occur in recent years. Let's be in this area. Considering the importance of the issue and the occurrence of floods in Esfand 1402 in this region, in this research, the identification of flooded areas and also the analysis of factors affecting its occurrence have been done.Materials and methodsIn this research, Sentinel 1 and 2 radar images, Landsat 9 images, and a digital model at a height of 30 meters have been used as the most important research data. The most important research tools are the Google Earth Engine system (to prepare maps of flooded areas and land cover maps) and ArcGIS (to prepare the desired maps). Also, in this research, fuzzy logic model has been used to identify vulnerable areas against flood risk. According to the topic and objectives, this research has been done in several stages. In the first stage, using radar images before the flood and images after the flood, a map of the flooded areas has been prepared. In the second stage, the role of natural factors (elevation, slope, distance from the river, and ranking of the river and land cover) in the flood has been analyzed. In the third stage, based on the results obtained from the previous stages and according to the extent of the flooded areas in different floors, various parameters have been valued and standardized, and finally, by combining the desired parameters based on the fuzzy gamma operator, a map of the damage areas is created. It has been prepared against flood risk.Discussion and resultsIn this research, the Google Earth Engine system was used to identify the flooded areas in the study area. After preparing the desired images and also applying filters and specifying the threshold limit in Google Earth Engine system, a map of the flooded areas in the southeast of Sistan and Baluchistan province was prepared in March 1402. According to the prepared map, a large part of the southeastern counties of Sistan and Baluchistan province have faced floods, but Dashtiari county and especially its southeastern regions along the Pakistan border have faced the highest amount of flooding. After Dashtiari city, Chabahar city has faced the highest amount of flooding. The analysis of the effective factors in the floods has shown that the height, slope and type of land cover have the highest influence because in a general trend, with the decrease in height, decrease in slope and also decrease in vegetation density, the extent of flooded areas increased.ConclusionThe results of the identification of flooded areas using radar images have shown that in March 1402, a large part of the region, especially the south-eastern areas of Dashtiari city, faced the risk of flooding. The results of the analysis of the effective factors in the floods have shown that a large part of the flooded areas were related to low altitude and low slope areas, which indicates the direct role of altitude and slope in the floods of the region. Also, the areas that were in the category of desert and barren lands in terms of land cover also had the highest percentage of flooding, so the type of land cover was also one of the effective factors. But the interesting point is that there was no strong relationship between the parameters of the distance from the river and the ranking of the river with the floods that occurred. That is, some areas that were far from the main rivers also faced floods, the main reason of which was the morphological condition of the rivers in the region. According to the mentioned cases, among the effective factors, the height and slope have the highest influence and the distance from the river has the least influence (among the studied parameters). Also, in this research, based on the condition of flood-affected areas and the influence of parameters, vulnerable areas against flood risk have been identified. Based on the results, the southern regions of the study area, including the middle and southern parts of Dashtiari city, the eastern and southern regions of Chabahar city, as well as the southern regions of Konarak city, have the highest flood potential.Keywords: Flood, Sistan and Baluchistan, Google Earth Engine.
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