برآورد و ارزيابي روند تغييرات تبخير – تعرق مرجع سالانه براساس پارامترهاي اقليمي مؤثر در شمال شرق ايران

Estimating and Evaluating the Trends of Annual Refrence Eevapotranspiration based on Influential Climatic Parameters in the North East of Iran

تحليل روند تغييرات تبخير – تعرق مرجع در هر منطقه از اهميت بالايي برخوردار مي­باشد. در مطالعه حاضر، از ﻣﺎر ﭘﺎراﻣﺘﺮﻫﺎي اﻗﻠﯿﻤﯽ دوازده اﯾﺴﺘﮕﺎه ﻫﻮاﺷﻨﺎﺳﯽ واﻗـﻊ در ﺷـﻤﺎل ﺷـﺮق ﮐﺸـﻮر ، ﺑـﺮاي ﺗﺨﻤـﯿﻦ ﺗﺒﺨﯿـﺮ – ﺗﻌـﺮق ﻣﺮﺟـﻊ ﺑﺮاﺳﺎس ﻣﺪلﻫﺎي ﺗﺠﺮﺑﯽ ﭘﺎﭘﺎداﮐﯿﺲ و ﭘﻨﻤﻦ ﻣﻮﻧﺘﯿﺚ ﻓﺎﺋﻮ اﺳﺘﻔﺎده ﮔﺮدﯾـﺪ . ﺧﺮوﺟـﯽ ﻣـﺪل ﻫـﺎ ﺑﺮاﺳـﺎس روش ﻫـﺎي ﻣﺨﺘﻠـﻒ درونﯾﺎﺑﯽ ارزﯾﺎﺑﯽ و ﺳﭙﺲ ﻧﺘﺎﯾﺞ روش ﮐﻮﮐﺮﯾﺠﯿﻨﮓ ﺑﺎ RMSE ﮐﻤﺘﺮ در ﻣﺤﯿﻂ ﻧﺮماﻓﺰارArcGIS10/2، ﺑﻪﺻـﻮرت ﭘﻬﻨـﻪ ﻫـﺎي ﻫﻢ ﺗﺒﺨﯿﺮ- ﺗﻌﺮق ﻣﺮﺟﻊ ﻣﺸﺨﺺ ﮔﺮدﯾﺪ. روﻧﺪ ﺗﻐﯿﯿﺮات ﺑﺎ آزﻣﻮن ﻧﺎﭘﺎراﻣﺘﺮي ﻣﻦ– ﮐﻨﺪال )MK( ارزﯾـﺎﺑﯽ ﺷـﺪ. ﻧﺘـﺎﯾﺞ ﻧﺸـﺎن داد ﮐﻪ ﺑﯿﺸﺘﺮﯾﻦ و ﮐﻤﺘﺮﯾﻦ ﺗﺒﺨﯿﺮ– ﺗﻌﺮق ﻣﺮﺟﻊ ﺑﻪﺗﺮﺗﯿﺐ، در اﯾﺴﺘﮕﺎهﻫﺎي واﻗﻊ در اﺳﺘﺎنﻫﺎي ﺧﺮاﺳﺎن ﺟﻨﻮﺑﯽ و ﺷـﻤﺎﻟﯽ رخ ﻣﯽدﻫﺪ. ﺗﺒﺨﯿﺮ ﺗﻌﺮق ﻣﺮﺟﻊ ﮐﻞ ﻣﻨﻄﻘﻪ در ﻣﻘﯿﺎس ﺳـﺎﻻﻧﻪ ، از ﺷـﻤﺎل ﺑـﻪ ﺟﻨـﻮب روﻧـﺪي اﻓﺰاﯾﺸـ ﯽ دارد. ارﺗﻔـﺎع و ﻋـﺮض ﺟﻐﺮاﻓﯿﺎﯾﯽ در ﺗﻌﯿﯿﻦ ﭘﻬﻨﻪﻫﺎي ﻫﻢ ﺗﺒﺨﯿﺮ– ﺗﻌﺮق ﻣﺮﺟﻊ از وزن ﺑﯿﺸﺘﺮي ﺑﺮﺧﻮردار ﺑﻮدﻧﺪ. روﻧﺪ ﺗﻐﯿﯿﺮات زﻣﺎﻧﯽ ETO ﺳـﺎﻻﻧﻪ در ﺣﺎﻟﺖ اﻓﺰاﯾﺸﯽ ﻣﻌﻨﯽدار ﻣﺸﺎﻫﺪه ﺷﺪ. در ﮔﻨﺎﺑﺎد، ﺳﺒﺰوار، ﺑﺸﺮوﯾﻪ و ﻗﺎﺋﻦ روﻧﺪ اﻓﺰاﯾﺸﯽ ETO در ﺳـﻄﺢ 0/05 ﻣﻌﻨـﯽ دار ﺑﻮد. ﺷﯿﺐ ﮐﺎﻫﺸﯽ ﺗﺎ14 - ﻣﯿﻠﯽﻣﺘﺮ در ﺳﺎل در اﯾﺴﺘﮕﺎهﻫﺎي ﺑﺠﻨﻮرد و ﻗﻮﭼﺎن و ﺷﯿﺐ اﻓﺰاﯾﺸﯽ ﺗﺎ17 ﻣﯿﻠﯽﻣﺘـﺮ در ﺳـﺎل در اﯾﺴﺘﮕﺎهﻫﺎي ﻓﺮدوس و ﻣﺸﻬﺪ در ﺳﺮي ﺳﺎﻻﻧﻪ ﺗﺨﻤﯿﻦ زده ﺷﺪ. روﻧﺪ ﺗﻐﯿﯿﺮات ﺳﺎﻻﻧﻪ ﭘﺎراﻣﺘﺮﻫﺎي اﻗﻠﯿﻤﯽ، ﻓﻘﻂ ﺑـﺮاي ﺑـﺎرش و رﻃﻮﺑﺖ ﻧﺴﺒﯽ اﯾﺴﺘﮕﺎه ﺑﯿﺮﺟﻨﺪ ﻣﻌﻨﯽدار ﺑﻮد. در ﭘﺎراﻣﺘﺮﻫﺎي ﮐﻤﯿﻨﻪ دﻣﺎ، ﺑﯿﺸﯿﻨﻪ دﻣﺎ و ﺳﺎﻋﺎت آﻓﺘﺎﺑﯽ در ﺗﻤﺎم اﯾﺴـﺘﮕﺎه ﻫـﺎ، ﺷﯿﺐ ﺗﻐﯿﯿﺮات ﻓﻘﻂ اﻓﺰاﯾﺸﯽ و ﺑﺮاي ﺳﺮﻋﺖ ﺑﺎد، ﺑﺎرش و رﻃﻮﺑﺖ ﻧﺴﺒﯽ ﺗﻐﯿﯿﺮات ﺷﯿﺐ ﻫﻢ ﺑـﻪ ﺻـﻮرت اﻓﺰاﯾﺸـﯽ و ﻫـﻢ ﺑـﻪ ﺻﻮرت ﮐﺎﻫﺸﯽ ﻣﺸﺎﻫﺪه ﺷﺪ. ﺑﻨﺎﺑﺮاﯾﻦ، ﻋﺎﻣﻞ اﺻﻠﯽ اﻓﺰاﯾﺶ ﺗﺒﺨﯿﺮ– ﺗﻌﺮق ﻣﺮﺟـﻊ در ﻣﻨﻄﻘـﻪ، روﻧـﺪ اﻓﺰاﯾﺸـﯽ ﭘﺎراﻣﺘﺮﻫـﺎي ﮐﻤﯿﻨﻪ دﻣﺎ، ﺑﯿﺸﯿﻨﻪ دﻣﺎ و ﺳﺎﻋﺎت آﻓﺘﺎﺑﯽ ﺑﻮده و در اوﻟﻮﯾﺖ دوم، ﺗﻐﯿﯿﺮات اﻓﺰاﯾﺸﯽ و ﮐﺎﻫﺸـﯽ ﭘﺎراﻣﺘﺮﻫـﺎي رﻃﻮﺑـﺖ ﻧﺴـﺒﯽ ﺑﺎرش و ﺳﺮﻋﺖ ﺑﺎد ﻧﯿﺰ ﺣﺎﺋﺰ اﻫﻤﯿﺖ ﻣﯽﺑﺎﺷﺪ.

Analysis of the trends of refrence evapotranspiration in any region is very important. In the present study, data of twelve meteorological stations in the North East of Iran, were used to estimate refrence ETo using Papadakis and FAO Penman–Monteith empirical models. The outputs of the models were evaluated based on different interpolation methods and then the results of the Cokriging method with lower RMSE were identified as the refrence evapotranspiration zones using the ArcGIS10/2. Trends were evaluated using the Mann-Kendall (MK) nonparametric test. The results revealed that the highest and lowest values of refrence evapotranspiration took place in stations located in the provinces of South and North Khorasan respectively. The annual ETo showed upward trend from north to south. Altitude and latitude had greater weights in determination of refrence evapotranspiration zones. The temporal trends of annual ETo were increasingly insignificant at 0.05%. The upward trends in Gonabad, Sabzevar, Boshrooyeh and Gha’een were significant at 0.05% level. An annual decreasing trend line slope was estimated up to -14 mm in Bujnoord and Ghoochan stations, whereas positive slope up to 17 mm in Ferdows and Mashhad stations were observed. Trends of climatic parameters were significant only for precipitation and relative humidity in Birjand station. Regarding the parameters of minimum temperature, maximum temperature and sunshine hours, the trends were upward in all the stations, and the changes for wind speed, precipitation and relative humidity were both upward and downward. Therefore, the main causes of increased potential evapotranspiration in the region were minimum temperature, maximum temperature and sunshine hours. The falling and rising changes of relative humidity, precipitation and wind were significant as well.