Application of AquaCrop and CropWat Models for Estimating Crop Water Requirement and Irrigation Scheduling of Maize in Metekel Zone, Ethiopia

The objective of the study was to compare AquaCrop Model with CropWat Model to estimate crop water requirement and irrigation scheduling of maize in the Metekel Zone. It also tries to compare the efficiency of Models for adoption in different situations in the study area. Crop water requirement and irrigation scheduling of maize in the study area were estimated using the CropWat Model based on soil, crop, and meteorological data. However, AquaCrop Model wasbased on soil, crop, and meteorological data including Co2, groundwater, field management, and fertility management condition. From the study, it was observed that the maximum reference evapotranspiration in the study area was found to be 7.1 mm/day in Guba and the minimum reference evapotranspiration was 2.9 mm/day in the Bullen district. The maximum ETo in all districts was found to in March and the lowest in August. The maximum ETc of maize was foundto be 702.4mm in the Guba district and the minimum ETc was found to be 572.6mm in Bullen district using CropWat but the effective rainfall for maize was determined as 185mm in the Wembera district. However, using the AquaCrop Model the maximum ETc of 565 mm was recorded in Guba but 425 mm was recorded as a minimum in the Wembera district for irrigated maize in the study area. From the study, it was observed that irrigation scheduling with a fixedinterval of 10 days with 12 irrigation events performed best. Moreover, the result revealed that there was a strong relationship and a significant relation between the simulated and observed values for validation. The model performance indicators showed that AquaCrop Model was well simulated in all parameters considered. Therefore, AquaCrop Model was found to be the most suitable soil-water-crop-environment management Model. So future studies should focus onaddressing deficit irrigation strategy with different field management conditions to improve agricultural water productivity under irrigated agriculture for the study area for major crops.