An Entropy-Based Hybrid MCDM Framework for Temporal Drought Assessment: A Case Study of Erzurum (Türkiye)

The growing water demand and shift in climatic conditions accentuate drought impacts on regional water resources. This study applies a comparative MCDM framework based on Entropy weighting, TOPSIS and VIKOR to evaluate monthly drought conditions using multiple climatic variables. Erzurum Province in eastern Türkiye, characterized by a high-altitude continental climate and a snow-influenced hydrological regime, was selected as the study area. Twelve monthly climatic parameters covering the 2012–2024 period were analyzed. Within the 2012–2024 record, Seasonal Mann–Kendall tests indicated significant upward tendencies in temperature, mean vapor pressure, and total vapor pressure, whereas precipitation showed no statistically significant tendency. Given the relatively short observation period, these results represent mid-term tendencies and should not be interpreted as evidence of long-term climatic change. Entropy weighting yielded the highest weights for evaporation (0.3091), precipitation (0.1813), and temperature (0.1524), representing matrix information density rather than direct physical causation. Using the adopted literature-based classification thresholds, Entropy-TOPSIS classified 97 months (67.36%) as drought-affected, compared with 70 months (48.61%) for Entropy-VIKOR. Sensitivity analysis showed that these absolute drought frequencies varied with the selected threshold values. However, their underlying continuous scores exhibited strong inverse rank alignment (Spearman’s ρ = −0.917, p < 0.001), achieving an 81.25% categorical agreement (Cohen’s κ = 0.629). Sensitivity testing confirmed rank structure stability even upon excluding evaporation, though TOPSIS displayed greater parameter sensitivity than VIKOR. Standardized indices (SPI and SPEI) showed weak overall correspondence, aligning notably only at the 1-month scale. The results show that TOPSIS and VIKOR can rank monthly conditions similarly, but drought class assignments are sensitive to methodology and thresholds. In high-altitude and snow-affected environments like Erzurum, the combined consideration of multiple climate variables can contribute to a more cautious assessment of drought periods and support the sustainable management of water resources.