Determining the Productivity of Water and Wheat Using AquaCrop Model under the Fixed Sprinkler Irrigation System in Basrah Governorate / Al-Luhais Region

Abstract

A field experiment was conducted during the season 2021/2022 in Basrah governorate/ Al-Zubair - Al-Luhais region. The experiment was designed according to a randomized complete block design (RCBD) with three replicates, it uses the results of regional climate models to knowledge how climate change effects on the region through the AquaCrop model and repeat the same process for another regional climate model and another scenario to assess the impact using climate projections and analyze the impact of climate change on water resources The results are as follows:

1. 1. The seasonal water consumption under the fixed sprinkler irrigation system reached 717 mm in the Al-Zubair- Al-Luhais region
2. A decrease in the amount of annual rainfall during the two periods (2021-2035) and (2035-2050) amounted to -7.04 and -11.65 mm, and -6.37 and -12.24 mm, respectively, compared to the base period (1985-2005) as an average of climate models (EC-Earth, CNRM-CM5, GFDL-ESM2M) for RCP4.5 and RCP8.5 scenarios respectively.
3. An increase in the maximum and minimum temperatures of 2.31 and 1.64°C, respectively, during the period (2021-2035) compared to the base period, with a clear increase in temperatures during the period (2035-2050) compared to the base period of 2.63 and 1.87°C for degrees maximum and minimum temperatures, respectively and an increase in both the maximum and minimum temperatures of 2.78 and 1.80° C, respectively, during the period (2021-2035) compared to the base period, with a clear increase in temperatures during the period (2035-2050) compared to the base period, amounting to 3.70 and 2.12° C for the maximum and minimum temperatures, respectively, as an average of the climate model values (EC-Earth, CNRM-CM5, GFDL-ESM2M) under the RCP4.5 and RCP8.5 scenarios.
4. The calibration gave a good agreement for most of the approved standards, and the correlation coefficient R² reached a very good agreement of 0.98. The RMSE gave a good agreement of 0.15. The value of the Woltman coefficient for comparison between the measured productivity and the expected productivity recorded a very good agreement, amounting to 0.96.
5. An increase in productivity in the scenario RCP 4.5 and RCP 8.5 when comparing the base period with the two periods (2021-2035) and (2035-2050), in addition to an increase in the relative change in productivity with non-significant differences between productivity during the base period and the simulation period, as the highest value of productivity during the period (2021-2035) amounted to 8.22 and 7.68 Ton ha^-1 of the wheat crop during the simulation period. The increase in the production rate between the periods (2021-2035) and (2035-2050) compared to the base period was 30.21, 28.48%, 32.87, and 30.64%.
6. Increasing water productivity in the RCP 4.5 and RCP 8.5 scenarios, and comparing the base period with the two periods (2021-2035) and (2035-2050), highest value of water productivity during the period (2021-2035) amounted to 7.72 and 7.70 kg m³, respectively.