Akademik Veri Yönetim Sistemi
12th INTERNATIONAL NEW YORK CONFERENCE ON EVOLVING TRENDS IN INTERDISCIPLINARY RESEARCH & PRACTICES, New York, Amerika Birleşik Devletleri, 21 - 24 Ağustos 2025, cilt.1, ss.25, (Özet Bildiri)
In monitoring drought events and characteristics, the literature reveals that standardized indices often
employ specific threshold levels, such as 0, -0.5, -1.0, -1.5, and -2. Each of these thresholds corresponds
to a certain probability level, statistically defined by the standard deviation of the index. In studies of
meteorological drought, the -1.0 level is commonly used as the threshold between mild and moderate
drought, often serving as the onset indicator of a drought event. For hydrological drought
characterization, thresholds of -0.5 and -1.0 are typically preferred as the initiation levels. At the same
time, in reservoir operations and water management, values of -1.5 and below are occasionally
considered operational thresholds. Since hydrological processes exhibit delayed responses and vary
considerably across regions, determining which threshold level to apply in hydrological drought studies
is even more debatable. Moreover, the use of a single standardized threshold often proves misleading.
The aim of this study is to evaluate statistically critical threshold levels from the perspective of water
resources management and decision-support systems. For this purpose, the Streamflow Drought Index
(SDI) was applied within the Konya Closed Basin at 6- and 12-month time scales, analyzing how
thresholds of 0, -0.5, -1.0, -1.5, and -2.0 influence drought duration and intensity. This approach
examines the extent to which threshold selection is critical for drought characteristics, under what
conditions alternative thresholds are more appropriate, and in which cases a single standard threshold
may lead to misinterpretation. The results demonstrate that threshold selection is crucial in identifying
long-lasting and severe drought events. Findings highlight the necessity of using basin-specific,
purpose-oriented calibrated thresholds in hydrological drought assessments. This study contributes to
the systematic evaluation of threshold-related uncertainties in hydrological drought research, offering
insights applicable to reservoir operations, irrigation planning, and early warning systems.