Evaluation of Various Surface Residue Cover Managements Effect on Actual ET Estimation Using SIMDualKc Crop Model

The objective of this study was to evaluate SIMDualKc crop model and then simulating different scenarios of surface residue cover. This model estimates evapotranspiration with dual crop coefficient approach. Therefore¡ that enables investigation of various mulch effects on evapotranspiration amount. Five management scenarios (organic mulch with densities of 0.2¡ 0.3¡ 0.4¡ 0.5 and 0.6) were simulated with SIMDualKc crop model during the 2001 and 2002 growing seasons. SIMDualKc model calibration and validation was performed with the results of 2 years data obtained from wheat field experiments located in Aboreihan University College of Tehran University. Then¡ climate¡ soil¡ crop and irrigation management data were inserted into model. The model estimated soil available water with model efficiency (EF) of 0.902 and calculating thefollowing evaluation criteria: RMSE=1.34 mm¡ absolute error = 0.955 mm and mean relative error = 4.67 %.with lack of required data for calibration¡ using FAO-56 standard crop and soil evaporative parameters resulted in reasonable accuracy. Various scenarios of crop residue mulch simulation results showed that with increase of organic mulch density¡ the ratio of evaporation to evapotranspiration (E/ET) decreased and transpiration rate increased. While ratio of E/ET was 18% w/o crop residue mulch¡ by applying organic mulch with density of 0.6 Kg/m2 decreased to 8%.