نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانش آموخته‌ی کارشناسی ارشد مهندسی آبخیزداری، گروه حفاظت آب و خاک، دانشگاه تربیت مدرس، تهران، ایران

2 استاد، گروه مهندسی آبخیزداری، دانشکده منابع طبیعی، دانشگاه تربیت مدرس، تهران

3 استاد، گروه مهندسی آبخیزداری، دانشکده منابع طبیعی، دانشگاه تربیت مدرس، تهران، ایران

چکیده

خشک‌سالی از ویژگیهای اصلی و تکرار شـونده‌ی اقلـیم‌های مختلف و هم‌چنین یکی از وقایع محیطی و بخش جدایی ناپذیر نوسـانات اقلیمی است. سامانه‌های پایش در تدوین طرح‌های مقابله با خشکسالی و مدیریت آن از اهمیت بسیاری برخوردار می‌باشد و به همین دلیل از شاخص‌های کمی موجود برای بیان این پدیده استفاده می‌گردد. از آنجا که این شاخص‌ها به صورت نقطه‌ای محاسبه می‌گردد، لازم است که به صورت مکانی پردازش شود. در این راستا از روش‌های میانیابی و از جمله زمین آمار استفاده می‌شود. در این پژوهش تحلیل و چگونگی تغییرات زمانی خشک‌سالی هواشناسی و همچنین قابلیت روش‌های کریجینگ، کوکریجینگ، عکس فاصله وزنی (IDW) و تابع شعاعی (RBF)، در تحلیل مکانی خشکسالی هواشناسی در کل حوزه آبخیز کارون مورد ارزیابی قرار گرفت. تحلیل خشک‌سالی با استفاده ازداده‌های بارندگی 58 ایستگاه بارانسنجی و 11 ایستگاه سینوپتیک با طول دوره آماری 30 ساله در بازه زمانی 66-1365 تا 95-1394 با استفاده از شاخص بارش استاندارد شده (SPI) انجام گرفت. سپس نقشه‌های خشکسالی تهیه و مورد ارزیابی قرار گرفت. نتایج بدست آمده نشان داد که کمترین مقدار ریشه میانگین مربعات خطا (RMSE) مربوط به روش کوکریجینگ با مقدار (32/0)، و روش تابع شعاعی با مقدار (34/0)، و این روش به عنوان بهترین روش برای سال (92-1391) می‌باشد. هم‌چنین سال (87-1386)، بیشترین ایستگاه‌ها درگیر خشک‌سالی خیلی شدید و سال (79-1378)، بیشترین ایستگاه درگیر خشک‌سالی شدید بودند. نتایج نشان داد که روش کوکریجینگ از دقت بالاتری نسبت به سایر روش‌ها در پهنه‌بندی خشک‌سالی برخوردار است.

کلیدواژه‌ها

عنوان مقاله [English]

Investigating temporal and spatial changes of meteorological drought (SPI) in Karun watershed

نویسندگان [English]

  • Mozhgan Moradi 1
  • Hamid Reza Moradi 2
  • Mehdi Vafakhah 3

1 M.Sc. Graduate, Department of Watershed Management Engineering, Faculty of Natural Resources, TarbiatModares University, Noor, Iran

2 Professor, Department of Watershed Management Engineering, Faculty of Natural Resources, Tarbiat Modares University, Noor, Iran.

3 Professor, Department of Watershed Management Engineering, Faculty of Natural Resources, Tarbiat Modares University, Noor, Iran.

چکیده [English]

Drought is one of the main and repeated features of different climates and also one of the environmental events and an integral part of climate fluctuations. Monitoring systems are very important in developing plans to deal with drought and its management, and for this reason, available quantitative indicators are used to express this phenomenon. Since these indices are calculated pointwise, it is necessary to process them spatially. In this regard, mediation methods including geostatistics are used. The analysis and how the meteorological drought changes over time, as well as the ability of kriging, cokriging, image distance weighted (IDW) and radial function (RBF) methods, were evaluated in the spatial analysis of meteorological drought in the entire Karun large watershed. Drought analysis was done using rainfall data from 58 rain gauge stations and 11 synoptic stations with a statistical period of 30 years in the period from 1987 to 2016 using the standardized precipitation index (SPI). Then drought maps were prepared and evaluated. The obtained results showed that the lowest value of the root mean square error (RMSE) related to the cokriging method with a value of (0.32), and the radial function method with a value of (0.34), and this method is considered the best method for the year 2013 is Also, in the year 2008 most stations were involved in very severe drought and year 2000, most stations were involved in severe drought. The results showed that the Cokriging method has higher accuracy than other methods in drought zoning.

کلیدواژه‌ها [English]

  • geostatistics
  • SPI index
  • rain gauge station
  • drought
  • monitoring systems
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