تغییرات مکانی و زمانی نرخ فرونشست گرد و غبار شهر یزد و ارتباط آن با برخی پارامترهای اقلیمی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه علوم و مهندسی آب، دانشکده کشاورزی و منابع طبیعی، دانشگاه اردکان

2 دکتری علوم و مهندسی آب، دانشکده کشاورزی و منابع طبیعی، دانشگاه اردکان

3 استادیار دانشکده کشاورزی و منابع طبیعی دانشگاه اردکان

چکیده

فرونشست گرد و غبار به طور گسترده در مناطق خشک و نیمه خشک جهان اتفاق می‌افتد. این مطالعه به منظور بررسی ویژگی‌های زمانی و مکانی گرد و غبار اتمسفری در شهر یزد و ارتباط آن با پارامترهای اقلیمی انجام شد. گرد و غبار به صورت فصلی در یک دوره یکساله از پائیز 1397 تا تابستان 1398 و از 30 نقطه با استفاده از تله‌های رسوبگیر نصب شده در بام ساختمان‌های یک طبقه نمونه-برداری شد و نرخ فرونشست گرد و غبار تعیین گردید. نتایج نشان داد که کمترین نرخ فرونشست گرد و غبار در فصل تابستان با میانگین 27/13 گرم بر متر مربع و بیشترین مقدار آن با میانگین 41/23 گرم بر مترمربع در بهار مشاهده گردید و متوسط نرخ فرونشست سالانه گرد و غبار در منطقه مورد مطالعه در طی یک سال داده برداری 7/72 تن بر کیلومتر مربع بدست آمد. نمودارهای همبستگی نشان داد که ضریب همبستگی منفی و پائین بین نرخ فرونشست گرد و غبار با دمای حداقل (28/0=R2) و دمای حداکثر (19/0=R2) وجود دارد. هر چند همبستگی مثبت و قوی در خصوص داده‌های متوسط باد (941/0=R2) و حداکثر سرعت باد (905/0=R2) و همبستگی مثبت ولی پائین با تعداد مشاهدات گرد و غبار (09/0=R2) مشاهده گردید. به نظر می‌رسد از بین پارامترهای اقلیمی، سرعت باد در منطقه مورد مطالعه تاثیر بیشتری بر وقوع رخدادهای گرد و غبار و هم چنین بر میزان نرخ فرونشست گرد و غبار داشته است. با توجه به نقشه‌های پهنه‌بندی، جهت باد غالب، بازدید از مناطق مختلف در حین نمونه‌برداری و هم چنین نقشه هوائی از منطقه در نواحی شمال و شمال غربی و شرق منطقه بیابان‌های بدون پوشش گیاهی و بدون ساختمان وجود دارد که باعث شده در این مناطق نرخ فرونشست بیشتر باشد و کمترین میزان نرخ فرونشست در ایستگاه‌های نمونه‌برداری مرکز شهر با ساختمان‌های بلند مسکونی و اداری در این مناطق، مشاهده گردید. . تعامل بین خصوصیات مختلف نقاط نمونه‌برداری گرد و غبار از جمله ارتفاع، نزدیکی به مناطق پرترافیک و پرتردد، نزدیکی به مناطق انجام عملیات عمرانی، فاصله از مناطق تولید گرد و غبار، جهت باد غالب و میزان و پراکنش بارش و سرعت باد بر نرخ فرونشست گرد و غبار در نقاط مختلف منطقه مورد مطالعه تاثیر گذاشته و منجر به توزیع غیریکنواخت نرخ فرونشست گرد و غبار در منطقه شده است.

کلیدواژه‌ها

عنوان مقاله [English]

Spatial and temporal Variability in the dust deposition rate of Yazd city and its relationship with some climatic parameters

نویسندگان [English]

  • Somayeh Soltani-Gerdefaramarzi 1
  • Mohsen Ghasemi 2
  • Mohammad Javad Ghaneie-Bafghi 3

1

2 PhD of Water Engineering, Faculty of Agricalture and Natural Resource, Ardakan University

3 Assistance Professor, Faculty of Agricalture and Natural Resource, Ardakan University

چکیده [English]

Dust subsidence occurs widely in arid and semi-arid regions of the world. This study was conducted to investigate the temporal and spatial characteristics of atmospheric dust in Yazd. Dust was sampled seasonally from autumn 2018 to summer 2019 and from 30 points using sediment traps installed on the roofs of one-story buildings and the dust subsidence rate was determined. The results showed that the lowest dust subsidence rate in summer with an average of 13.27 g /m2 and the highest value with an average of 23.41 g/m2 was observed in spring and the average annual dust subsidence rate in the study area was found 72.7 tons/km2. Correlation charts showed that there is a negative and low correlation coefficient between the dust subsidence rate with minimum temperature (R2 = 0.28) and maximum temperature (R2 = 0.19). However, positive and strong correlation was observed with mean wind data (R2 = 0.941) and maximum wind speed (R2 = 0.905) and positive but low correlation with the number of dust observations (R2 = 0.09). Among the climatic parameters, wind speed in the study area seems to have had a greater impact on the occurrence of dust events as well as the rate of dust subsidence. According to the zoning maps, the prevailing winds, visiting different areas during the sampling, as well as the Google map of the area in the northern and northwestern and eastern areas of the region, there are deserts without vegetation and without buildings. In these areas, the subsidence rate has been higher and the lowest subsidence rate has been observed in the sampling stations of the city center with tall residential and office buildings in these areas. Interaction between different characteristics of dust sampling points such as altitude, proximity to high-traffic and high-traffic areas, proximity to areas of civil activities, distance from dust production areas, prevailing wind direction and amount and distribution of wind speed and wind speed on the rate dust subsidence has affected different parts of the study area, leading to an uneven distribution of dust subsidence rates in the area.

کلیدواژه‌ها [English]

  • Atmospheric dust
  • spatial and temporal distribution
  • subsidence rate
  • climatic parameters
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