Accurate estimation of actual evapotranspiration using remote sensing data for improved water management in the Moghan plain

Document Type : Research Paper


1 Department of Water Engineering, Faculty of Agricultural and Natural Resources, Imam Khomeini International University, Qazvin, Iran

2 Imam Khomeini International University



Spatial quantification of actual evapotranspiration is highly important for water resource management and planning in arid regions. This study focused on the investigation and estimation of evapotranspiration using the Py_SEBAL and METRIC algorithms, the WaPOR model, and the MOD16 product in the Moghan plain, located in Ardabil province, during the years 2021 and 2022. The results of each model were compared with the FAO-56 method, which is a standard approach for estimating evapotranspiration in different regions. The results demonstrated that the Py_SEBAL algorithm had the highest correlation with the FAO-56 values, with an R value of 0.97 and an RMSE value of 1.88 (mm/month). Subsequently, the METRIC algorithm exhibited the highest correlation with an R value of 0.89 and an RMSE value of 1.5 (mm/month). To further validate the performance of the estimation models in different areas, the WaPOR database was also utilized. The obtained outputs indicated that among the irrigated areas, the Py_SEBAL algorithm had the highest correlation with the values derived from WaPOR, with an R2=0.77. Following Py_SEBAL, the METRIC algorithm showed a relatively good correlation with an R2 =0.55. Considering the land use map of the region, over 60% of the area was covered by irrigation networks. Since Py_SEBAL yielded the best results for these areas in the conducted investigations, the estimation of evapotranspiration volume was conducted at the overall regional level. The obtained results indicated that the evapotranspiration volume from the irrigated areas was approximately 4.5 times higher than that from the rainfed areas.


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