Analysis of drought trend in the Yeşilırmak Basin with statistical approaches

Drought refers to water scarcity resulting from below-normal precipitation in a specific region and for a specific period of time. Analysis of droughts is of vital importance in terms of water resources planning and management, hydroelectric energy production, irrigation planning, agricultural productivity and reservoir planning. Therefore, droughts should be observed with various indices and their changes should be analyzed. In this study, drought status was evaluated according to the Standard Precipitation Index (SPI), Standardized Precipitation Evapotranspiration Index (SPEI) and De Martonne Index (DMI) values calculated between 1979 and 2022 for the monthly, seasonal and annual time periods for Amasya, Çorum, Samsun and Tokat meteorological stations located in the Yeşilırmak basin and station-based drought percentages were expressed. In addition, each drought index was subjected to trend and change point analyzes according to Şen's Innovative Trend Analysis (ITA), Ardışık Mann Kendall (SQMK) and Innovative Polygon Trend Analysis (IPTA) methods. According to the analyzes, the trends and trend start years of droughts in the region were determined and it was revealed that severe droughts were dominant at a level of 15% in the region. As a result of ITA analyses, it was determined that there was a significant decreasing trend at the stations at the level of 5 10% in the spring, summer, autumn and annual period in general, together with an increasing drought trend. As a result of SQMK analyses, a significant decreasing trend was observed in the stations in general. As a result of IPTA analyses, it was emphasized that increasing drought intensities were dominant in the trend analyses of SPI, SPEI and DMI. In this context, it is of great importance for policy makers and decision makers to be prepared for drought risks that may be encountered in the basin.