کمّی سازی عوامل محیطی و انسانی در وقوع آتش سوزی جنگل با روش های rs و gis؛ مناطق حفاظت شده ارسباران

در این تحقیق، کمّی‌سازی عوامل محیطی و انسانی در وقوع و گسترش آتش‌سوزی جنگل در منطقه جنگلی حفاظت شده ارسباران، مورد بررسی قرار گرفته است. برای این منظور با ترکیب داده‌های سنجش از دور و سیستم اطلاعات جغرافیایی، از باندهای انعکاسی و حرارتی تصاویر ماهواره‌ای لندست 8، مدل رقومی ارتفاعی زمین، سرعت و جهت باد، پوشش گیاهی، دمای سطح زمین، شیب، جهت شیب، نزدیکی به جاده‌ها و مناطق مسکونی به عنوان عوامل طبیعی و انسانی استفاده شده است. ابتدا با تلفیق این داده‌ها، نقشه مناطق خطر آتش‌سوزی جنگل تولید گردید و سپس نقشه مناطق با ریسک 50 درصدی آتش‌سوزی تولید شد. برای بررسی و اعتبار سنجی نتایج حاصل، داده‌های مرجع آتش‌سوزی‌های پیشین مورد استفاده قرار گرفت.  نتایج کمّی پارامترهای مذکور نشان دادند که پوشش گیاهی با 58/36 درصد هم‌بستگی، شیب با مقدار 38/38 درصد دارای بالاترین تاثیر و سایر پارامترها در مراتب بعدی در انتشار آتش‌سوزی قرار دارند. همچنین نتایج مقادیر ضرایب هم‌بستگی نرمال شده این پارامترها نشان داد که به ترتیب شاخص‌های پوشش گیاهی، دمای سطح زمین، جهت شیب و شیب با 29/20%، 29/11%، 21/93% و 19/75%،بالاترین میزان هم‌بستگی با نقشه خطر وقوع آتش‌سوزی را دارند. همچنین، نتایج ارزیابی نقشه پتانسیل آتش‌سوزی با ریسک 50 درصدی نشان داد که حدود 17% منطقه دارای پتانسیل خیلی‌زیاد بوده و بیش‌تر از 50 درصد منطقه در وضعیت خطر زیاد برای آتش‌سوزی قرار دارد. علاوه بر عوامل محیطی، بررسی ارتباط عوامل انسانی با خطر آتش‌سوزی نشان داد که عامل نزدیکی به جاده بیش‌ترین سهم را در ایجاد وقوع آتش‌سوزی در منطقه دارد. نتایج کمّی عوامل انسانی در وقوع خطر آتش‌سوزی نشان داد که راه‌های ارتباطی و مناطق مسکونی به ترتیب حداقل 32 درصد و حداکثر 68 درصد هم‌پوشانی با خطر وقوع آتش‌سوزی در منطقه مطالعاتی را دارا هستند.

Quantifying environmental and human factors affecting occurance and spread of wildfires using RS and GIS methods protected area of Arasbaran

Extended Abstract Introduction Forests play numerous critical roles in nature. They stabilize and fertilize soil, purify water and air, store carbon, and nurture environments abundant in biodiversity. Moreover, forests offer numerous job opportunities and hidden wealth toany economy. Unfortunately, wildfires have turned into a serious natural risk nowadays. Wildfires are a natural disaster threatening forests and ecosystem, from local to global level. Evaluating the risk of wildfires is an important factor in fire management. This can be performed at different spatial and temporal scales: global and local; short term, and longterm. At global scales, it can contribute to the establishment of general guidelines for fire management at continental level, while at local scales,it is more suitable for resources focusing on preventing specific fires in small regions. Longterm estimation addresses general, more permanent planning of firefighting resources, which is related to the more structural factors affectingwildfires or their spread, such as topography or terrain characteristics, vegetation structure, human activities or weather patterns.   Materials & Methods Wildfire risk has become a major concern in recent years, particularly in areas where human settlements are in close proximity to forests. Wildfire origin canbe determined largely by environmental factors. However, fire related data is either unavailable, or mostly incomplete. Thus, reaching an overall annual estimate of wildfires is difficult. Some common methods are used toestimate the risk ofwildfires, including qualitative methods, quantitative methods based on specialized knowledge (multicriteria evaluation techniques), regression techniques (linear regression and logical regression), and artificial neural networks. Wildfire initiation and spread depend on several important factors, including precipitation, presence of ignition elements, factors like topography, temperature, thunder, spreading of fuel, relative humidity, wind speed, and etc. The present study integrates data produced by remote sensing with data received from geographic information system. It also takes advantage of LDCM satellite imagery, and digital elevation model, along with natural/human factors such as wind speed and direction, vegetation, land surface temperature, slope, proximity to roads and residential areas. The present study seeks to quantify environmental and human elements effective in occurrence and spread of wildfires in the protected jungles of Arasbaran. To this end, a risk zone map was produced for the area, along with a map for areas with 50% risk. In the present study, the final map of risk zone was produced using the Fire Risk Index (FRI) and spatial statistics method.   Results & Discussion In the present study, factors such as land cover type, slope, distance from residential area, distance from the road, and elevation were taken into account. During the process, different indices were assigned to each class of these factorsbased on their sensitivity to fire or their flammability. Land cover was one of the most important factors affecting the occurrence of wildfires. Slope was another important factor with a significant influence on the spread of fire. This natural factor affects fire spread and fire intensity. Proximity of human settlements to jungles is another important factor which sometimes threatsjungles. Therefore, forests in proximity of human settlements face a higher risk of wildfires. Elevation is another important topographical factorclosely related to wind behaviour, with a significant role in fire spreading. In Arasbaran forest, northern, eastern, and northeasternareas are more elevatedand thus, more prone to wildfires. In this study, a combination of environmental and human factors was applied to produce fire hazard maps along with a map for areas with 50% risk of wildfire.   Conclusion Occurrence and spread of wildfires depends on many factors, some of which are more important and play a more significant role in these fires. A risk zone map was produced for wildfiresusing an integrated method consisting ofremote sensing and GIS methods. Risk zone was divided into 5 areas, i.e. very low, low, average, high, very high.Results indicate that the methodology presented based on a combination of RS and GIS techniquesin this study, is a reliable approach and tool for the prevention and mitigation of forest fires. They are also useful for all active institutes working in crisis management and emergency services, while helping jungle protectingorganizations to prevent fires or manage them. In addition, quantitative results indicate that vegetation index with a correlation of 58.36%, and slope with a correlation of 38.38 are the most affective factors, and other parameters are in the next ranks.Moreover, land cover, land surface temperature, direction, and slope with 29.20%, 29.11%, 21.93% and 19.75% normalized correlation coefficient respectively, have the highest correlation with the map of fire risk zone. In addition, results of evaluating 50% risk zone map indicate that around 17% of the study area have a high fire risk and more than 50% of the area is located in a high fire risk zone. In addition to environmental elements, results indicate that proximity to the road was the most affective factor in the occurrence of fire. Quantitative results showed that roads and residential areas were at least 32% and at most 68% correlated with fire risk in the study area.