The evaluation of the drought effect in the Western Black Sea basin by using the trend analysis techniques

Protection and operation of water resources has maintained its importance throughout human history. Today, with the effect of global warming, basin planning and drought prevention studies have gained much more importance. This situation makes it essential for us to consider the future conditions of our current river resources. A downward trend to be detected in rivers is closely related to the determination of the drought effect in that region. In this article, the Western Black Sea Basin was examined and the trend presence in the rivers of the region was investigated and evaluated in terms of drought. Out of 126 flow observation stations located in the Western Black Sea Basin, 23 with suitable data were selected, and firstly, minimum flows were compiled and then the missing data were completed with the Regression Equations method. Subsequently, the data were subjected to trend analysis. Trend analysis methods were examined and analyzes were made with non-parametric Mann-Kendall, Spearman's Rho Test, Sen's Trend Slope Method and Şen's Innovative Trend Analysis Test methods. The Mann-Kendall Rank Correlation Method was used to determine the start dates of the trends. Among the analyzed stations, a decreasing trend in 4 stations and an incresing trend in 2 stations were detected. Although no trend was detected, a tendency to decreasing trend were observed in 3 stations and a tendency to increasing trend in 4 stations, and no trend and tendency was found in 13 stations. When the analyzes were examined, similar results were determined in many stations. The results of all methods were examined at the stations where differences were observed, and the closest results were obtained. The results of the analysis studies were processed on the map and evaluations were made according to the risks and opportunities overlapped with the irrigation areas. According to the results of the study, a single trend representing the entire basin cannot be mentioned for the Western Black Sea Basin. In the basin, risky areas in terms of drought and regions that offer opportunities in terms of agricultural production have been identified. In this differentioan, The geographical,topographic,climatic,geological structure and similar effects can be effective. The study revealed that customized policies should be developed for various locations, as there is no single trend that reflects the entire Western Black Sea Basin.