Analysis of changes in reference crop water consumption (ETo) for central Black Sea region

In this study, using the meteorological data of five meteorological stations (Samsun, Tokat, Ordu, Amasya and Çorum) in the Central Black Sea Region, monthly, seasonal (MI: January-March; M-II: April-June; M-III: July-September; M-IV: October-December) and annually (YT) reference evapotranspiration (ET0) values calculated according to the Penman-Monteith relationship were aimed the determination of the change. First, it was tested whether the data were normally distributed. Thus, it was targeted to prefer parametric or non-parametric approaches in the homogeneity analysis of the data. The homogeneity of the normally distributed data was examined whether the difference in the mean and variance of the relevant data was statistically significant. The non-parametric Mann-Whitney U approach was used in the homogeneity analysis of the data that was not normally distributed. The data not having the homogeneity condition were homogenized by the double-mass curve method. After these processes, analysis of the change in the data, Mann-Kendall (MK), Spearman Rho (SR), Linear Regression (LR) and Innovative Trend Analysis (YTA) tests were performed. The YTA results reveal a statistically significant change in approximately 32% of the ET0 series. However, this finding is around 16% in the MK test, 20% in the SR test and 13% in the LR test. This study will be beneficial to the stakeholders on the subject in terms of the possible threats depending on the changes in the climatic elements in the region.