ارزيابي مكاني-زماني داده هاي تبخير-تعرق واقعي پايگاه هاي جهاني در حوزه آبخيز سد كرخه

Evaluation of temporal- spatial global terrestrial actual evapotranspiration data in Karkhe Dam Watershed

تبخير - ﺗﻌﺮق ﺑﻪﻋﻨﻮان ﯾﮑﯽ از ﻣﺆﻟﻔﻪ ﻫﺎي ﺑﯿﻼن آب، ﻧﻘﺶ ﻣﻬﻤﯽ در ﺗﻮزﯾﻊ ﻣﮑﺎﻧﯽ و زﻣﺎﻧﯽ آب در دﺳﺘﺮس دارد. ﺑﻪدﻟﯿﻞ ﻣﺤﺪودﯾﺖﻫﺎي اﻧﺪازه ﮔﯿﺮي زﻣﯿﻨﯽ ﺗﺒﺨﯿﺮ-ﺗﻌﺮق واﻗﻌﯽ در ﻣﻘﯿﺎس ﺣﻮﺿﻪ، روش ﻫﺎي ﻣﺨﺘﻠﻔﯽ ﻣﺒﺘﻨﯽ ﺑﺮ اﻃﻼﻋﺎت ﺳﻨﺠﺶ از دور و ﻣﺪلﻫﺎي ﻫﯿﺪروﻟﻮژﯾﮑﯽ ﺑﺮاي ﺑﺮآورد اﯾﻦ ﻣﺆﻟﻔﻪ ﺑﯿﻼن آب ﺗﻮﺳﻌﻪ ﯾﺎﻓﺘﻪ اﺳﺖ. ﻫﺪف از اﯾﻦ ﭘﮋوﻫﺶ، ارزﯾﺎﺑﯽ ﻣﯿﺰان دﻗﺖ داده ﻫﺎي ﺗﺒﺨﯿﺮ-ﺗﻌﺮق واﻗﻌﯽ ﻣﺪلﻫﺎي ﭘﺎﯾﮕﺎه ﺟﻬﺎﻧﯽ MYD16 ،MOD16 و SSEBOP ﺑﺮاي ﻣﻘﯿﺎسﻫﺎي زﻣﺎﻧﯽ ﻣﺎﻫﺎﻧﻪ و ﻓﺼﻠﯽ در اراﺿﯽ ﺑﺎ ﮐﺎرﺑﺮي ﻣﺨﺘﻠﻒ در ﺷﺮاﯾﻂ ﺳﺎل ﻫﺎي ﺗﺮ، ﺧﺸﮏ و ﻧﺮﻣﺎل در ﺳﻄﺢ ﺣﻮﺿﻪ ﺑﺰرگ ﺳﺪ ﮐﺮﺧﻪ اﺳﺖ. ﺑﺮاي اﯾﻦ ﻣﻨﻈﻮر، اﺑﺘﺪا ﻣﺪل ﻫﯿﺪرﻟﻮژﯾﮑﯽ SWAT ﺑﺮ ﻣﺒﻨﺎي اﻃﻼﻋﺎت ﺟﺮﯾﺎن ﭘﺎﯾﻪ و آﺑﺪﻫﯽ اﯾﺴﺘﮕﺎهﻫﺎي ﻫﯿﺪروﻣﺘﺮي و ﺗﻐﯿﯿﺮات ﺣﺠﻢ آﺑﺨﻮان ﻫﺎي واﻗﻊ در ﺳﻄﺢ ﺣﻮﺿﻪ ﮐﺮﺧﻪ واﺳﻨﺠﯽ و اﻋﺘﺒﺎرﺳﻨﺠﯽ ﺷﺪ. ﭘﺲ از اﻃﻤﯿﻨﺎن از دﻗﺖ ﻋﻤﻠﮑﺮد ﻣﺪل، در ﺑﺮآورد ﻣﺆﻟﻔﻪ ﻫﺎي ﺑﯿﻼن آب در ﺳﻄﺢ ﺣﻮﺿﻪ ﻣﻮرد ﻣﻄﺎﻟﻌﻪ، از ﻣﻘﺎدﯾﺮ ﺗﺒﺨﯿﺮ-ﺗﻌﺮق واﻗﻌﯽ ﺷﺒﯿﻪ ﺳﺎزي ﺷﺪه اﯾﻦ ﻣﺪل ﺑﺮاي ارزﯾﺎﺑﯽ زﻣﺎﻧﯽ-ﻣﮑﺎﻧﯽ دﻗﺖ داده ﻫﺎي ﺗﺒﺨﯿﺮ-ﺗﻌﺮق واﻗﻌﯽ ﻣﺪلﻫﺎي ﭘﺎﯾﮕﺎه ﻫﺎي ﺟﻬﺎﻧﯽ ﺑﻬﺮه ﮔﺮﻓﺘﻪ ﺷﺪ. ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد ﮐﻪ ﻫﺮ ﺳﻪ ﻣﺪل، ﻣﻘﺎدﯾﺮ ﺗﺒﺨﯿﺮ-ﺗﻌﺮق واﻗﻌﯽ ﺑﺮآورد ﺷﺪه را ﺑﺎ اﺧﺘﻼف ﻣﻌﻨﯽ داري ﻧﺴﺒﺖ ﺑﻪ ﻧﺘﺎﯾﺞ ﻣﺪل SWAT ﮐﻤﺘﺮ ﺑﺮآورد ﻣﯽ ﮐﻨﻨﺪ. ﺑﻪ ﻃﻮري ﮐﻪ ﻣﻘﺎدﯾﺮ RMSE و MBE ﺑﻪﺗﺮﺗﯿﺐ از 15 ﺗﺎ 21/74 و 15/93- ﺗﺎ 8/19- ﻣﯿﻠﯽ ﻣﺘﺮ در ﻣﻘﯿﺎس ﻣﺎﻫﺎﻧﻪ و از 40/17 ﺗﺎ 59/32 و 47/74- ﺗﺎ 19/36- ﻣﯿﻠﯽ ﻣﺘﺮ در ﻣﻘﯿﺎس ﻓﺼﻠﯽ در ﺳﻄﺢ ﺣﻮﺿﻪ ﻣﺘﻐﯿﺮ ﺑﻮد. ﻫﻢ ﺧﻮاﻧﯽ ﺑﯿﻦ ﻧﺘﺎﯾﺞ داده ﻫﺎي ﺗﺒﺨﯿﺮ-ﺗﻌﺮق واﻗﻌﯽ ﻣﺪلﻫﺎي ﭘﺎﯾﮕﺎه ﻫﺎي ﺟﻬﺎﻧﯽ ﺑﺎ ﻣﻘﺎدﯾﺮ ﺷﺒﯿﻪﺳﺎزي ﺷﺪه ﻣﺪل SWAT در ﺳﺎل ﮐﻢ ﺑﺎرش در ﻣﻘﺎﯾﺴﻪ ﺑﺎ ﺳﺎل ﻫﺎي ﭘﺮ ﺑﺎرش و ﻧﺮﻣﺎل ﮐﻤﺘﺮ اﺳﺖ. اﮔﺮ ﭼﻪ ﻧﺘﺎﯾﺞ ﻣﺪل SSEBOP داراي ﺧﻄﺎي ﮐﻤﺘﺮي در ﻣﻘﺎﯾﺴﻪ ﺑﺎ ﻣﻘﺎدﯾﺮ ﺧﺮوﺟﯽ ﻣﺪل SWAT ﺑﻮد، اﻣﺎ روﻧﺪ ﺗﻐﯿﯿﺮات زﻣﺎﻧﯽ ﺗﺒﺨﯿﺮ-ﺗﻌﺮق واﻗﻌﯽ ﻣﺪلﻫﺎي MOD16 و MYD16، ﻫﻢﺧﻮاﻧﯽ ﺑﯿﺸﺘﺮي ﺑﺎ ﺳﺮي زﻣﺎﻧﯽ داده ﻫﺎي ﻣﺪلSWAT داﺷﺖ. ﻫﻤﭽﻨﯿﻦ ﻧﺘﺎﯾﺞ ﻧﺸﺎن داد، در زﯾﺮﺣﻮﺿﻪﻫﺎي ﺑﺎ ﮐﺎرﺑﺮي ﻏﺎﻟﺐ ﮐﺸﺎورزي، ﻣﺪل SSEBOP و در زﯾﺮﺣﻮﺿﻪﻫﺎي ﺑﺎ ﮐﺎرﺑﺮي ﺟﻨﮕﻞ و ﻣﺮﺗﻊ، ﻣﺪلﻫﺎي MYD16 و MOD16 از ﺧﻄﺎي ﮐﻤﺘﺮي، ﺑﺮﺧﻮردار ﻫﺴﺘﻨد

Evapotranspiration has a key role on spatial and temporal distribution of available water, as vital component of water balance. ET ground measurements at large scale has limitation, so, different methods have been developed to estimate actual ET based on remote sensing data. The purpose of this study was to evaluate accuracy of actual ET estimation for MOD16, MYD16 and SSEBOP global database models in monthly and seasonal time scales for different land use and wet, dry and normal climate conditions at Karkheh Dam Basin. First, SWAT model was calibrated and verified based on data of hydrometric stations included: river discharge, base flow and aquifer storage. After ensuring the accuracy of SWAT model performance in estimating water balance components at the studied basin, simulated actual evapotranspiration values were used to evaluate the temporal-spatial accuracy of actual evapotranspiration data of global database models. Results showed that all three models underestimate actual evapotranspiration values with a significant difference from the SWAT model results. The RMSE and MBE values varied from 15 to 21.74 and -15.93 to -8.19 mm on a monthly scale and from 40.17 to 59.32 and -47.74 to -19.36 mm on a seasonal scale, respectively. The concordance between the actual evapotranspiration results of the global database models and the simulated SWAT model values ​​in the dry year is lower than wet and normal years. Although the results of the SSEBOP model had less error than SWAT model, the actual evapotranspiration time variations of the MOD16 and MYD16 models were more consistent with the time series data of the SWAT model. The results also showed that in the dominant agricultural basins, the SSEBOP model and in the forest and pasture basins, the MYD16 and MOD16 models have less error.