Assessment of Radiation Use Efficiency Model in Estimating Biomass and Yield of Irrigated Wheat Based on Landsat 8 and 9 Satellite Images (Case Study: the Urmia Lake Basin)

Given that conventional ground-based methods require significant costs, time, and manpower, there is an increasing inclination towards using indirect methods such as remote sensing. Therefore, the aim of this research was to calculate dry biomass, harvest index, and grain yield of irrigated wheat using remote sensing in the Urmia Lake Basin. For this purpose, the Urmia Lake Basin was divided into six sub-basins, and the Radiation Use Efficiency (RUE) model was utilized. In this study, 1115 irrigated wheat fields were used. Monitoring results of the fields and the NDVI index indicated that irrigated wheat germination in the basin began on average from November 11th, and harvesting of this crop continued until July 21th. The values of correlation coefficient (R), Nash-Sutcliffe coefficient (NSE), normalized root mean square error (nRMSE), and coefficient of residual mass (CRM) in the calibration step were 0.90, 0.76, 15%, and 6.38%, respectively, and in the validation step, they were 0.92, 0.72, 14%, and 7.21%, respectively. Examination of the harvest index (HI) indicated that the average of this index in different sub-basins ranged from 0.40% to 0.45%, with an overall average of 0.42% for the Urmia Lake Basin. The results of biomass and grain yield assessment revealed significant differences in their values among different sub-basins. The highest biomass and grain yield were observed in the Zarrineh-Simineh sub-basin with averages of 12098 and 5261 kilograms per hectare, respectively, while the lowest values were observed in the West-Lake sub-basin with averages of 8651 and 3723 kilograms per hectare, respectively.