Temporal Trends and Drought Risk Evaluation in the Semi-arid Kilis Region of Türkiye

Drought is an increasing challenge in semi-arid border regions where climatic stress intersects with demographic pressure. Kilis Province, located along the southern border of Türkiye, is particularly vulnerable because declining water availability coincides with rising demand associated with migration-driven population growth. This study presents a 67-year drought assessment for Kilis using the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI) at 3-, 6-, and 12-month timescales, together with a Landsat-based monthly Normalized Difference Vegetation Index (NDVI) time series for 2000–2025 as a complementary indicator of vegetation response. Drought characteristics were compared between two consecutive sub-periods, 1959–1991 and 1992–2025, and long-term climatic trends were evaluated using the Mann–Kendall test. The results showed a significant decrease in annual precipitation and a significant increase in annual mean temperature. Both SPI and SPEI exhibited statistically significant negative trends across all timescales, with the strongest drying signal at the 12-month scale. The inter-period comparison further indicated intensification of long-term drought conditions during the recent period. Correlations between NDVI anomalies and drought indices were weak and statistically non-significant, suggesting that NDVI should be interpreted as a complementary vegetation-response indicator rather than a direct validation tool for meteorological drought indices. Overall, the findings reveal progressive drought intensification in Kilis and provide evidence relevant to drought preparedness and water-resource planning.