تغییرات مکانی تبخیرتعرق مرجع در استان کرمانشاه

نوع مقاله : یادداشت فنی

نویسندگان

گروه مهندسی آب، پردیس کشاورزی و منابع طبیعی، دانشگاه رازی

چکیده

با توجه به تغییرات مکانی و کمبود اندازه‌گیری‌های نقطه‌ای تبخیر‌تعرق، استفاده از روش‏های درون‌یابی جهت برآورد‌ مکانی این کمیت ضروری به نظر می‌رسد. هدف از این مطالعه برآورد تبخیرتعرق مرجع (ETo) در سطح استان کرمانشاه و مقایسه آن با سند ملی آب کشور می‌باشد. به این منظور، داده‌های روزانه هواشناسی 38 ایستگاه در استان کرمانشاه و استان‌های همجوار از سازمان هواشناسی اخذ گردیده و برای محاسبه و پهنه‌بندی ETo به سه روش بر اساس فرمول پنمن و پنمن- مانتیث استفاده شد. در روش‌های اول و دوم، ابتدا داده‌های هواشناسی درون‌یابی و سپس ETo بر اساس آن داده‌ها محاسبه شد، در حالی که در روش سوم ابتدا مقادیر ETo در ایستگاه‌های سینوپتیک محاسبه و سپس درون‌یابی انجام گرفت. به این منظور کل استان به 366 یاخته با ابعاد 10×10 کیلومتر تقسیم و با استفاده از نرم‌افزار CGMS درون‌یابی شد. نتایج نشان داد که ETo تغییرات مکانی قابل توجهی درسطح استان دارد. به طور کلی می‌توان گفت مناطق غربی که دمای بیشتر و ارتفاع کمتری دارند، تبخیر‌تعرق بالاتری دارند. مقادیر ETo محاسبه شده در استان کرمانشاه بر اساس روش پنمن– مانتیث بیشتر از روش پنمن بود. گرچه کمیت ETo در سند ملی آب کشور بر اساس فرمول پنمن– مانتیث محاسبه شده ولی مقدار آن در دشت‌های استان با مقادیر برآوردی با روش اول (فرمول پنمن) مطابقت داشت.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Spatial variation of reference evapotranspiration in Kermanshah province

نویسندگان [English]

  • Iman Ebrahimi Haftcheshmeh
  • Bahman Farhadi Bansouleh
Water Engineering Department,, Faculty of Agriculture, Razi University
چکیده [English]

Due to the spatial variations of evapotranspiration, and lack of adequate point estimations using interpolation methods for spatial analysis is necessary. The aim of this study was to estimate the regional values of reference evapotranspiration (ETo) in Kermanshah province, west of Iran and comparison with Iran National Water Document. For this purpose, daily weather data of 38 meteorological stations of Kermanshah and neighboring provinces were obtained from the Iran Meteorological Organization. Three methods were used for calculation and zoning of ETo, based on Penman and Penman-Monteith equations. In the first and second methods, the meteorological data were interpolated and then ETo was calculated using the interpolated data, while in the third method the point estimation of ETo (weather stations) were interpolated. For the purpose of interpolation, the CGMS software was used in a gridded network of 366 cells with 10 × 10 km size. The results showed that there exist a significant spatial variations ETo across the province. In general, in the western regions of the province, with higher temperature and lower altitude, higher values of ETo was observed. The ETo estimations based on Penman-Monteith method were higher than Penman method. Although the ETo values presented in the Iran National Water Document are calculated by the Penman-Monteith equation, but obtained amount for plain regions of the province are more consistent with Penman- equation estimations.

کلیدواژه‌ها [English]

  • CGMS
  • evapotranspiration
  • Geostatistics
  • Interpolation
  • Penman-Monteith
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