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Abstract Mohamed Hosny Hassan Abdel Kader: Evapotranspiration Estimation Using Remote Sensing Data and some Climatic Models. Unpublished M.Sc Thesis, Department of Soil Science, Faculty of Agriculture, Ain Shams University, 2016. Satellite remote sensing is one of the promising sources of data to estimate the regional evapotranspiration based on the energy balance system. This study aims to assess the estimated values of evapotranspiration using the surface energy balance system (SEBS model) and four climatic models widely used including Penman-Monteith (FAO 56, PM), Penman (FAO 24, P), radiation (R), and HargreavesSamani (HS). Remote sensing model (SEBS) was used to estimate daily actual evapotranspiration values for wheat, sugarbeet, green onions, and potato winter crops as well as peanut and fodder maize summer crops, and citrus perennial crop using seventeen Landsat 7 ETM+ satellite images and the agrometeorological data representing the 2012/2013 winter and 2013 summer seasons. The selected site represents a private farm (6th October agricultural company) located in Ismailia governorate (31.92 and 32.62 E longitudes and 30.38 and 30.52 N latitudes). Results revealed that, there were clear differences between the estimated Eto values using the tested PM, R, P and HS climatic models. Average Eto values were 8.2, 6.0, 5.5, and 5.2 mm/day for PM, R, P, and HS methods, respectively. Relationships between Eto values estimated by FAO56 PM and the P, R, and HS methods were developed using the regression analysis. High coefficient of determination values indicate that the developed equations can be used within the range of the examined values to describe the relationship between Eto estimated by the four climatic methods. Results indicated also that, there were differences between the estimated Eta values using the tested climatic models. Average Eta values were 7.7, 6.0, 5.4, and 4.5 mm/day for PM, R, P, and HS methods, respectively. The Eta values estimated by SEBS, P, R, and HS methods were lower than those estimated by PM method. Estimated Eta values using SEBS model were generally low as compared with those estimated by the tested climatic models. The seasonal actual evapotranspiration values for the studied winter crops using SEBS, PM, P, R, and HS methods were 384, 574, 382, 450, and 329 mm/season for wheat, 450, 758, 537, 594, and 482mm/season for sugarbeet 164, 256, 16, 207, and 135 mm/season for potato crop, and 306, 614, 414, 508 and 360 mm/season for green onion crop, respectively. For the summer season, the Eta values obtained from the same respective methods were 405, 1099, 722, 880, and 876 mm/season for peanut crop, 429, 1086, 703, 874, and 826 mm/season for fodder maize crop, and 878, 1496, 987, 1208, and 1077 mm/season for citrus crop. The substantial differences between actual evapotranspiration Eta values for the same crop using the different climatic models, revealed the essential need to get accurate crop coefficients under field conditions. Results showed that, the estimated applied irrigation water by PM, P, R, HS, and SEBS methods and added at the farm were 4019, 2677,3149, 2302, 2688, and 3024 m3/fed, respectively for wheat crop, 5303, 3758, 4156, 3372, 3150, and 4234 m3/fed for sugarbeet crop, 1792, 1232, 1451, 948, 1148, and 3528 m3/fed for potato crop, 4300, 2899, 3557, 2522, 2142, and 3750 m3/fed for green onion, 7603, 4924, 6119, 5783, 3000, and 3000 m3/fed for fodder maize crop, 7695, 5055, 6158, 6131, 2836, and 3200 m3/fed for peanut crop, and 8269, 5457, 6677, 5953, 4854 and 6912 m3/fed citrus crop. Results indicate that, the remote sensing model (SEBS) needs more verification and validation studies to evaluate all the factors that might affect the quality of data used for calculating the surface energy balance under arid lands condition. In conclusion, more studies, in several successive seasons for various crops, are recommended before using the SEBS model for estimating the actual evapotranspiration at the field level and consequently in the actual crop coefficient values. |