Actual and Predicted Evapotranspiration Along with Groundwater Contribution for Wheat Crop

Abstract

This experiment aimed to determine the crop evapotranspiration (ET_c), groundwater input in total water used by wheat crop, and to simulate the CROPWAT model to envisage the crop evapotranspiration rate. To estimate on-field ET_c and groundwater contribution the combining lysimeter technique was used. The water levels below the soil surface were kept at 1.60, 2.20, and 2.80 m and each water table depth was replicated three times. The experiment was conducted under silt loam (SL) and silty-clay loam (SCL) soil conditions. The climatic parameters and water balance components were recorded accordingly. The on-field ET_c was compared with the predicted ET_c by CROPWAT model. Under SL soil, the observed ET_c was 442, 427, and 401 mm at the water table depth of 1.60, 2.20, and 2.80 m, respectively. The recorded ET_c under SCL soil was 419, 402, and 389 mm at the same water table depths, respectively. The ET_c reduced with an increase in water level below the surface. The groundwater contribution at 1.60, 2.20 and 2.80 m depth of water level under SL and SCL soil was observed as 50, 41, and 30 % and 43, 34, and 24 %, respectively. The predicted ET_c by CROPWAT model for SL and SCL soil conditions was 428.8 and 410.7 mm, respectively. The projected ET_c is likely equal to the average ET_c observed under lysimeter experiment. Thus, the use of CROPWAT model is recommended to overcome waterlogging and salinity problems and to conserve water resources.