Hydrological low flow and overlapped trend analysis for drought assessment in Western Black Sea Basin

Abstract

Drought is a major disaster known for hundreds of years, but its impact has recently increased due to climate crisis, making it a common concern of the whole society worldwide. There is no clear definition of drought, as many disciplines evaluate it from different perspectives. Utilizing water and reducing the impact of drought are directly related issues. It is essential to determine our rivers' future conditions, reveal the effects of possible changes on drought, and take the necessary precautions against them in advance to prevent possible economic and social crises. In this study, among the 126 flow observation stations whose records were kept in the Western Black Sea Region, 26 observation stations with suitable data between 1984 and 2020 were selected to evaluate the drought effect. The Mann-Kendall Rank Correlation test was used to determine the starting years of the detected trends. In order to detect trends, the Spearman's Rho (SR) test, the Mann-Kendall (MK) test, Sen's Trend Slope (TS) method, & Scedil;en's Innovative Trend Analysis (ITA) test, and, Mann-Kendall Order Correlation (MKOC) test. According to all analysis methods, decreasing trends were detected at stations D13A014, D1A032, and E13A036. In addition, MKOC test results showed the trend starting in 2001 was at D13A014, 1990 at D13A032, and 1990 at E13A036. However, no significant trend was detected in minimum flows at other stations. It would be appropriate to make such studies on the evaluation of water resources a country policy and to conduct studies on the direction and value of drought in the basin in the future using trend analysis or other methods.