نوع مقاله : مقاله پژوهشی

نویسنده

استادیار گروه علوم و مهندسی آب، واحد مرودشت، دانشگاه آزاد اسلامی، مرودشت، ایران

چکیده

‌ فقدان یا کمبود ایستگاه‌هایی که بطور کامل حاوی چنین مشخصاتی باشند، اقلیم شناسان را ملزم به رعایت اصولی معین در ‌درون‌یابی ‌می‌سازد. در این تحقیق تلاش بر آن است که ضمن معرفی روش ‌درون‌یابی کریجینگ به عنوان یکی از روش‌های دقیق و پرکاربرد، مراحل انجام این فرآیند و انتخاب بهترین نوع از مدل کریجینگ با ذکر مطالعه‌ای موردی صورت گیرد. با توجه به روند رو به افزایش خشکسالی در کشور و نیاز به برنامه ریزی در مدیریت منابع آب، در مطالعه حاضر خشکسالی هواشناسی استان فارس مورد بررسی قرار گرفت. در این راستا شاخص خشکسالی هواشناسی استاندارد شده بارش SPI سه ماهه برای ایستگاه‌های سینوپتیک استان محاسبه گردید. شاخص SPI سه ماهه در مطالعات مرتبط با خشکسالی کشاورزی کاربرد بیشتری دارد. به منظور ‌درون‌یابی شاخص SPI سه ماهه در ابتدا سمی‌واریوگرام تجربی داده‌های محاسبه و ترسیم گشت. سپس 17 مدل کریجینگ بر سمی‌واریوگرام داده‌ها برازش یافت، و با استفاده از تکنیک ارزیابی متقاطع خطای تخمین مدلها برآورد گردید. نتایج نشان داد که مناسبترین مدل برازش داده شده بر داده‌های شاخص خشکسالی SPI سه ماهه ایستگاه‌ها، مدلهای خطی، توانی، ریشه دوم، لگاریتمی و گوسی کریجینگ معمولی ‌می‌باشد. با استفاده از نتایج حاصله، ارزیابی کفایت شبکه باران‌سنجی نیز ‌می‌تواند صورت گیرد. مدل گوسی به عنوان یکی از بهترین مدل‌های برازش یافته بیانگر پیوستگی مکانی بالای بارش در منطقه مورد مطالعه است. واریوگرام با فرض عدم وجود روند بر داده‌ها برازش داده شد. در نظر گرفتن روند خطی و غیر خطی،‌ و آنالیز نقشه‌های خطا ‌می‌تواند منجر به استخراج مدل‌های بهتر گردد.

کلیدواژه‌ها

عنوان مقاله [English]

Assessing SPI-3 months spatial variation using Kriging, Case study, Fars province

نویسنده [English]

  • Homa Razmkhah

Assistant Professor, Department of Water Science and Engineering, Marvdasht Branch, Islamic Azad University, Marvdasht, Iran

چکیده [English]

Due to the lack of facilities and commitment in climate stations establishment in large scale interpolation has become an important technique in spatial mapping studies. In this study, the Kriging interpolation technique as a prevalent technique has been explained and 17 Kriging models were evaluated, in order to select the most suitable one, using a case study. Because of increasing trend of drought in Iran and management necessity of water resources, meteorological drought of Fars province has been investigated in this study. For this purpose the calculated SPI-3 months of the Fars province synoptic stations were calculated. SPI-3 months is widely applied in agricultural drought studies. The empirical semi-variogram of the SPI-3 of the stations was calculated and graphed, fitting 17 Kriging models to select the best one using the cross-validation technique. Results showed that the Linear, Power, Square root, Logarithmic and Gaussian models were the best interpolation techniques for SPI-3 spatial mapping. Geostatistic methods could be used to determine the adequacy of the rainfall gauge stations, especially in the western mountainous region of the province. A complete-length of data could modify the results. The Gaussian model as one of the best-fitted models defines good spatial continuous of precipitation in the region. The semivariograms were fitted to data with the hypothesis of no precipitation trend. Considering the linear and non-linear trends of data, and analyzing error maps may result in better models.

کلیدواژه‌ها [English]

  • Interpolation
  • Drought
  • SPI
  • Kriging
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