Environmental Erosion Research

fa ارزیابی تغییرات زمانی- مکانی عناصر اقلیمی مؤثر بر وقوع پدیده گرد و غبار در مناطق خشک و نیمه‌خشک (مطالعه موردی: تالاب جازموریان) Evaluation of Temporal-Spatial Changes of Climatic Elements Affecting the Occurrence of Dust Phenomenon in Arid and Semi-arid Regions (Case Study: Jazmurian Wetland) مدلسازی و تحلیل زمانی و مکانی رخداد انواع مختلف فرسایش محیطی مستخرج از پایان‌نامه / رساله / طرح پژوهشی طوفان گرد و غبار پدیده‌ای است که به مرزهای سیاسی و طبیعی محدود نمی‌شود و منطقه وسیعی را تحتتأثیر قرار می‌دهد. بنابراین، هدف از این مطالعه، بررسی روند تغییرات زمانی- مکانی طوفان‌های گرد و غبار در تالاب جازموریان است. در این پژوهش با استفاده از داده‌های ماهواره‌ای سنجنده مودیس، اطلاعات مربوط به عمق نوری ذرات معلق در هوا (AOD) و شاخص پوشش گیاهی (NDVI) بررسی شد. سپس با استفاده از داده‌های هواشناسی دریافت شده از سازمان هواشناسی کشور، داده‌های اقلیمی بارندگی، دما، رطوبت نسبی، دید افقی، جهت باد و سرعت باد در بازه زمانی 1399-1379 ارزیابی شد و رابطه همبستگی بین شاخص AOD و سایر پارامترهای اقلیمی به دست آمد. نتایج بررسی عمق نوری نیز نشان داد که بیشترین میزان AOD، از نظر مکانی در قسمت‌های مرکزی تالاب قرار داشت. از سوی دیگر، کمترین میزان پوشش گیاهی، بارندگی، رطوبت نسبی و دید افقی، حداکثر دما، جهت و سرعت باد نیز در این مناطق مشاهده شد. بررسی روند تغییرات پارامترهای مورد بررسی با استفاده از شاخص من کندال و شیب تخمین‌گر سن نشان داد که روند تغییرات متوسط سالانه، در سطح معنیداری پنج درصد شاخص‌های سمت باد، سرعت باد و‌ دید افقی با شیب مثبت افزایشی بود. روند تغییرات شاخص‌های بارندگی و دما نیز در سطح معنیداری پنج درصد  نشان داد که روند این دو پارامتر افزایشی بود که این افزایش در دما محسوس‌تر است. روند تغییرات شاخص رطوبت نسبی نیز شیب منفی و کاهشی داشت. هبستگی بین عمق نوری و سایر پارامترها نشان داد که بیشترین همبستگی شاخص AOD در سطح معنیداری پنج درصد با پارامتر جهت باد بود و کمترین همبستگی را با شاخص رطوبت نسبی داشت. بنابراین، افزایش ذرات معلق در هوا به‌شدت به روند تغییرات پوشش گیاهی و شاخصهای اقلیمی بستگی دارد؛ به ‌نحوی که با استفاده از داده‌های ماهواره‌ای و اقلیمی با قدرت تفکیک مکانی و زمانی مناسب به‌خوبی مطالعه میشود.   1- Introduction Soil and air are two essential elements in the life of creatures on the earth. Their interaction in certain conditions can cause many risks; among these dangers, dust storms can be mentioned. Under the conditions of dust storms, a large amount of dust is emitted in the air and the horizontal visibility is reduced to less than 1000 meters. Therefore, due to the important role of the dust phenomenon, it is highly necessary to understand the spatial-temporal changes and to analyze their long-term variations. Jazmurian region, located in the southeast of Iran, between the two provinces of Kerman and Sistan and Baluchistan, has become completely dry and turned into a desert due to drought and construction of numerous dams, and has turned this region into one of the key areas of dust production in the country. Therefore, the purpose of this study is to investigate the temporal-spatial changes of dust storms in relation to climatic parameters in Jazmurian wetland, which is of particular importance in order to properly manage this area to face the problems caused by dust storms. 2- Methodology In order to carry out the present research, the meteorological data related to the synoptic stations located in the Jazmurian wetland area for a period of 20 years (2000-2020) were received from the Iranian Meteorological Organization. Climatic data used in this research include temperature, precipitation, relative humidity, wind speed and direction, horizontal visibility, and remote sensing data including Aerosol Optical Depth (AOD) and Normalized Difference Vegetation Index (NDVI). The research method uses a combination of statistical analysis, observation and remote sensing. In order to check the AOD and NDVI, the monthly data of MODIS sensor was used. In this study, 12 synoptic stations that had the longest and most complete statistical periods were used in order to identify the temporal-spatial changes of dust occurrence in Jazmurian wetlat. The Mann-Kendall test was used to examine the trend of time changes. The slope of the Sen estimator was used to check and confirm the accuracy of the trend changes. In order to better understand the spatial distribution pattern of dust events in the Jazmurian wetland basin, the inverse distance interpolation method (IDW) was used. Also, Pearson's spatial correlation analysis was used to investigate the mutual effects between the indicators. 3- Results The 20-year average review of the indicators showed that the maximum value of aerosol optical depth in the studied area was 0.3, which is seen in the central part of the wetland. The vegetation index also showed that the maximum value of this index was 0.2, which covers most of the northern, northwestern and western parts. Examining the average rainfall trend showed that the maximum and minimum rainfall in this period are about 219 and 85 mm, respectively. Meanwhile, the 20-year average temperature survey showed that the maximum and minimum temperatures were 28.7 and 17.2 degrees Celsius, respectively. The fact that the maximum rainfall is in the northern and western part is in harmony with the minimum temperatures in these areas. The examination of the average wind speed showed that the maximum speed was 3.6 m/s, which was mostly in the central, west and northwest, south and southwest parts. The results of the wind direction index showed that the lowest wind direction is in the northern parts of the region and the highest wind direction is in other parts of the Jazmurian wetland basin. The maximum humidity in the studied area is 43.73%, which is mostly seen in the north, northwest, west, south, and southwest parts.  Examination of the horizontal visibility index showed that the maximum amount of horizontal visibility was in the northeastern and northwestern parts of the region. Also, the process of changes in the Mann-Kendall test showed that the annual averages of the indicators of wind direction, wind speed and horizontal visibility have been increasing with a positive slope, and the trend of changes in the relative humidity index has a negative slope and indicates a decrease in the period of 20 years. The results of the correlation analysis (at a significance level of 5%) showed that the highest correlation of the optical depth index was with the wind direction parameter and the lowest correlation was with the relative humidity index. 4- Discussion & Conclusions The growing trend of the emission of dust particles caused by the phenomenon of wind erosion in recent decades has caused major concerns at different regional, national and global levels. Therefore, it is necessary to understand the temporal-spatial changes of the dust caused by these events in order to reduce their adverse consequences in different regions. Accordingly, in this research, with the help of this knowledge, information related to the optical depth of particles in the air (AOD) and the vegetation cover index (NDVI) were investigated using the MODIS sensor satellite data. Using the meteorological data received from the website of the National Meteorological Organization, the climatic data of rainfall, temperature, relative humidity, horizontal visibility, wind direction and wind speed were evaluated in the period of 2000-2020 and finally the correlation between the AOD index and other climate parameters was evaluated. The results of the optical depth investigation showed that the maximum optical depth is located in the central parts of Jazmurian wetland. The trend of changes in rainfall and temperature indicators also showed that the trend of these two parameters was increasing; this increase in temperature is more noticeable. Correlation investigation between optical depth and other parameters showed that the highest correlation of optical depth index was with the wind direction parameter and the lowest correlation was with the relative humidity index. In general, we can conclude that the optical depth of airborne particles is highly dependent on environmental factors, which is more evident in arid and semi-arid areas, especially in Iran and the Jazmurian wetland area. In recent years, the area of the wetland has acted as a source of dust. Therefore, by using the remote sensing data obtained from the MODIS sensor and the climate data, it is possible to examine and analyze the trend of dust changes in the units of time and space.   آزمون من کندال, پارامترهای اقلیمی, جازموریان, گرد و غبار, همبستگی. Dust, Jazmurian, Mann-Kendall Test, Climatic Parameters, Correlation 109 129 http://magazine.hormozgan.ac.ir/browse.php?a_code=A-10-66-7&slc_lang=fa&sid=1 Bahareh Jabalbarezi بهاره جبالبارزی bahareh.jabal.bar@ut.ac.ir 10031947532846008572 10031947532846008572 No Department of Reclamation of Arid and Mountains Regions, University of Tehran, Tehran, Karaj گروه احیای مناطق خشک و کوهستانی، دانشکده منابع طبیعی دانشگاه تهران، کرج Gholamreza Zehtabian غلامرضا زهتابیان ghzehtab@ut.ac.ir 10031947532846008573 10031947532846008573 No Department of Reclamation of Arid and Mountains Regions, University of Tehran, Tehran, Karaj گروه احیای مناطق خشک و کوهستانی، دانشکده منابع طبیعی دانشگاه تهران، کرج Hassa Khosravi حسن خسروی hakhosravi@ut.ac.ir 10031947532846008574 10031947532846008574 Yes Department of Reclamation of Arid and Mountains Regions, University of Tehran, Tehran, Karaj گروه احیای مناطق خشک و کوهستانی، دانشکده منابع طبیعی دانشگاه تهران، کرج Saeed Barkhori سعید برخوری barkhori.s@ujiroft.ac.ir 10031947532846008575 10031947532846008575 No Faculty of Natural Resources, University of Jiroft, Jiroft دانشکده منابع طبیعی دانشگاه جیرفت، جیرفت