Evaluation of meteorological, agricultural and hydrological drought in the Konya closed basin: the example of Beyşehi̇r and Karaman sub-basins

Drought is a critical issue in semi-arid regions, particularly where water resources are scarce and unevenly distributed, exerting significant environmental and socio-economic impacts. The Konya Closed Basin, one of the driest basins in Türkiye, is a notable region requiring close examination in this context. Drought, a natural disaster characterized by water shortage, varies spatially and temporally within meteorological, agricultural, and hydrological processes. In this study, these three types of drought were comprehensively evaluated for the Konya Closed Basin. The analyses employed the Standardized Precipitation Index (SPI), Agricultural Standardized Precipitation Index (aSPI), and Streamflow Drought Index (SDI) across different time scales. The Beyşehir-Kaşaklı and Karaman Ayrancı sub-basins were selected as the study areas; monthly precipitation and streamflow data from the Beyşehir and Karaman meteorological stations, as well as the Mavi, Taşağıl, Aşağı Esence, and Seyit Hasan streamflow observation stations, covering the period 1984–2022, were analyzed. SPI, aSPI, and SDI values were examined at 3-, 6-, and 12-month time scales to reveal the relationships among drought types across the basin. For each station, the longest drought periods, the highest severity values, their occurrence times, and frequency rates were determined, and the occurrence percentages of drought events in different severity classes were evaluated. Comparative assessments showed a strong correlation between SPI and aSPI results, whereas minor discrepancies were found between SPI and SDI, likely due to delays in streamflow response and groundwater abstraction. Ultimately, the simultaneous assessment of meteorological, agricultural, and hydrological droughts clearly revealed an increasing trend of aridity in the basin, along with the intensification of drought events over time.