شناسایی کانون‌های داخلی برداشت گردوغبار و مسیرهای انتقال آن در استان هرمزگان (مطالعه موردی: منطقه کوهستک تا بندرعباس)

هدف پژوهش حاضر شناسایی کانون‌های داخلی تولید گردوغبار در منطقه حدفاصل بندرکوهستک تا بندرعباس در استان هرمزگان است. داده‌های مورد استفاده شامل: کدهای هواشناسی ایستگاه‌های همدیدی منطقه، تصاویر ماهواره‌ای مودیس و برداشت‌های میدانی می‌باشد. روش مورداستفاده مبتنی‌بر مطالعات میدانی، تکنیک‌های دورسنجی و مدل سازی اقلیمی است که در این راستا از چهار الگوریتم بارزسازی tdi، ackerman، nddi، tiidi و مدل hysplit استفاده شده است. نتایج ارزیابی شاخص‌های مورداستفاده در بارزسازی گردوغبار منطقه بیانگر کارایی بهتر الگوریتم tdi است. نتایج بارزسازی همچنین نشان داد که کانون‌های برداشت و تولید گردوغبار متعددی در منطقه وجود دارند که این کانون‌ها در گستره وسیعی از منطقه موردمطالعه پراکنش دارند. پس از شناسایی کانون های گردوغبار منطقه، با استفاده از نقشه های تهیه شده و مطالعات میدانی مشخص شد که سه واحد رسوبات دشت‌های سیلابی (qal3)، رسوبات خاکریزهای طبیعی (qal2) و تلماسه‌های ساحلی (qdune)، بیشترین نقش را در تولید گردوغبار منطقه به عهده دارند. مسیریابی حرکت طوفان گردوغبار با استفاده از مدل انتشار لاگرانژی ذرات hysplit نشان داد که سه مسیرکلی ورود طوفان‌های گردوغبار به منطقه وجود دارد که شامل مسیر شمال شرقی، مسیر غربی و مسیر ‌جنوب غربی می‌باشند. همچنین بر اساس نتایج مدل، مشخص شد که ادامه حرکت طوفان در منطقه در مسیرهای متفاوتی بوده که مسیر شمال و شمال‌شرقی با 30 درصد، مسیر جنوبی 25 درصد و مسیر شرقی 20 درصد از مجموع رخدادهای دوره مطالعاتی 2000 تا 2018 را شامل می شود.

Dust Storms Trajectories and Identification of the Internal Sources over Hormozgan Province: A Case Study on Kohestak- Bandar Abbas, south of Iran

Today, the existence of numerous sources of dust production is one of the environmental challenges of Hormozgan province. Remote sensing and using MODIS data is one of the effective methods for the detection and mapping of dust storms. At first, meteorological data of all synoptic stations in the study area were collected and analyzed. According to the results, the highest frequency of dust occurrence is related to the three months of July, August, and May, which are in spring and summer. October, December and November have the lowest occurrence of dust storms in the study area. Also, autumn with 12.5% has the lowest occurrence of dust storms in all stations in the study area, and spring with 34.4%, and then summer with 33.6% has been recorded as the highest occurrence of the dust storms. This research monitors and evaluates four detecting algorithms for identification of plume and dust source and dust storm emission in the Kostak Bandar Abbas area in the Hormozgan Province using MODIS satellite data and the HYSPLIT model. Ackerman’s model, Normalized Difference Dust Index (NDDI), Thermalinfrared Dust Index (TDI), and thermal Infrared Integrated Dust Index (TIIDI) were four Algorithm methods for dust source and plume identification using MODIS Level 1B and MODIS Level 2 data. The results show that all of the algorithms except NDDI were successful in detecting dust plumes, but the most effective algorithm for plumes identification varied from event to event. In addition, TDI is the best algorithm comparing its results with those of other three algorithms. The results show that there are a lot of dust sources in the study area that have many negative effects on other populated areas in the Hormozgan province and its neighboring areas. The results indicate that the Flood Plains Deposits (Qal3), Natural Levee Deposits (Qal2), and Coastal Dunes (Qdune) play the most important role in dust production in the study area. The HYSPLIT (Hybrid SingleParticle Lagrangian Integrated Trajectory) model was used to trace wind flow backward and forward to the study area. The results of the HYSPLIT model show that the dust particles are mainly transported to the study area from three main paths, namely, Northeastern, the West, and the Southwestern part of the study area. The results also, show that dust plumes lifted and dispersed towards different directions including the north and northeast with 30%, the south with 25%, and the east with 20% of the total events in the study period 2000 to 2018. In addition, the results show that the study area has a high potential for the occurrence of dust storms during the year as many dust hotspots have been identified in this area. Also, the occurrence of more than a decade of drought, the presence of erosionsensitive formations, and the presence of erosionsensitive sedimentary units in the study area and its surrounding areas, especially in the seasonal wetland Jazmourian has provided conditions to aggravate this situation. Due to the economic and tourism importance of cities such as Bandar Abbas, Qeshm, and Minab, and especially the industrial and economic region west of Bandar Abbas and the existence of active dust sources around this region, the need for executive operations and watershed management activities is highly recommended.