Estimation of irrigation water requirements of sunflower under the context of climate change in TR21 Thrace Region

In order to use water resources efficiently and sustainably, it is very important to determine the impact of climate change on water resources accurately. For this purpose, reference evapotranspiration (ET0), crop evapotranspiration (ETc), irrigation water requirement (IWR) was determined with CROPWAT 8.0 using climate data obtained from HadGEM2-ES and MPI-ESM-MR model reference period (1971-2000) and future short (2031-2040) and long (2051-2060) periods RCP4.5 and RCP8.5 scenario outputs for sunflower in TR21 Thrace Region. Afterwards, the results obtained for the reference period and future periods are compared and evaluated. As a result, it is estimated that ET0 values will increase by 6.3%-13.2% and 4.9%-26.9% in the upcoming short (2031-2040) and long (2051-2060) periods, respectively, compared to the reference period (1971-2000), and by 6.0%-13.0% and 3.4%-17.9% in the sunflower development period. ETc is predicted to increase by 3.5%-12.0% in the short term and 2.4%-16.9% in the long term, compared to the reference period, and IWR values are predicted to vary between 0.3%-19.9% in the short term and -7.0%-20.8% in the long term. In the TR21 Thrace Region, it is estimated that the annual average ET0, ET0 during the sunflower development period, and sunflower water consumption will be negatively affected by climate change in the future periods (2031-2040, 2051-2060) and will increase compared to the reference period. It is anticipated that there will be increases and decreases in irrigation water demand; however, the general trend is towards an increase, and it has been determined that these increases will be greater than the decreases. This study will guide producers, managers, and decision makers in carrying out adaptation activities against the impact of climate change on water resources.