جستجوی مقالات مرتبط با کلیدواژه "پنمن مانتیث" در نشریات گروه "اکولوژی"

Evapotranspiration is a complex phenomenon that depends on many factors and data, so determining it is very difficult and costly. In most methods mainly aimed at estimating evapotranspiration, point measurements have been used to estimate this variable. Therefore, it is only suitable on a local scale and cannot be extended to large basins due to the dynamics and regional changes of evapotranspiration (ET). One of the remote sensing algorithms for estimating real evapotranspiration is the Surface Energy Balance Algorithms for Land (SEBAL). In this algorithm, by estimating all energy components on the land surface such as pure radiation flux, soil heat flux, and tangible heat flux, using the energy balance equation, evapotranspiration is used. The aim of this study is to compare the estimation of real evapotranspiration using SEBAL algorithm in wheat and rapeseed crops with the results of estimating evapotranspiration by Penman-Monteith-FAO method in the field of Esmaeil Abad Agricultural Research Station in 2019-2020. Single-sample T-test of ground surface temperature reflection index showed that the spectral reflection of wheat and rapeseed crops during phenological growth period had a significant difference. The results showed that the computational values of the two models are relatively good and the mean value of square root of error (RMSE) in estimating real evapotranspiration for wheat and rapeseed plants was 3.04 and 2.09 mm/day, respectively, and the coefficient of explanation (R2) was 0.78 and 0.81, respectively. The results showed that SEBAL algorithm model in comparison with Penman-Monteith-FAO model (based on up-to-date meteorological data) The amount of evapotranspiration for wheat and rapeseed plants is lower.

Evaluation of evapotranspiration is one way to prevent water loss and water resource management. Therefore, in this study, an attempt has been made to calculate the actual evapotranspiration rate in the east of East Azerbaijan province using the SEBAL algorithm. For this purpose, first, based on two Landsat 8 satellite images dated 2017/08/22 and 2017/08/09, the values of Net radiation, soil heat flux, and sensible heat flux are estimated. Then, based on the difference, the amount of instantaneous heat flux was calculated and 24-hour evapotranspiration was obtained for each image. Finally, the amount was compared with the values obtained from the Penman-Monteith method. Also, for processing and analyzing images ENVI4.8 software was used. The results indicated that the amount of evapotranspiration in the Penman-Monteith and SEBAL method on 2017/08/22 was about 6.15 and 7 mm per day, and on 2018/08/09, respectively, about 7.38 for Penman-Monty and 7.94 mm per day for SEBAL. Overall, the amounts of SEBAL actual evapotranspiration and Penman-Monteith potential evapotranspiration have a mean absolute difference (MAD) 0.705 mm per day which indicates that the estimated values are consistent with the SEBAL algorithm and the Penman-Monteith method.

Obviously, in any planning for qualitative and quantitative management of water resources, ýestimating the water balance and values of the input and output components that will play an ýimportant role. Several studies in the field of evapotranspiration most complex component of ýthe water balance in the world and many models offered and developedþ.þý Remote Sensing due to ýthe superiority of meteorological methods based on measuring point and water balance is more ýin the works. In this study, performance of Surface Energy Balance (SEBS) model to estimate ýactual evapotranspiration in Sistan plain is studied. For this purpose data from Zehak ýmeteorological stations and the technology of remote sensing and MODIS sensor images used. ýSurface flux of energy balance is calculated for each image pixel and actual evapotranspiration ýwere estimated by the remaining amount of the energy balance at the level. The results were ýcompared with results of two point ground-based data consist of the hay grown on the sidelines ýof Zahak synoptic station and water level of reservoir of Chahnime1. Model showed good ýperformance for both land and water based on correlation coefficient value with 0.78 and 0.89 ýrespectively.ý