Decoupled Magnitude and Dynamics of Hydrological Extremes: Low- and High-Flow Trends and Drought-to-Flood Transitions in the Yeşilırmak Basin, Türkiye
ENVIRONMENTAL MODELING & ASSESSMENT, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Basım Tarihi: 2026
- Doi Numarası: 10.1007/s10666-026-10173-y
- Dergi Adı: ENVIRONMENTAL MODELING & ASSESSMENT
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, IBZ Online, ABI/INFORM, Aerospace Database, Compendex, Environment Index, Geobase, Greenfile, Natural Science Collection (ProQuest), Materials Science & Engineering Collection (ProQuest), Pharma Collection (ProQuest), Technology Collection (ProQuest)
- Ondokuz Mayıs Üniversitesi Adresli: Evet
Özet
Trends in the magnitude of hydrological extremes and the dynamics of drought-to-flood transitions are usually studied separately, leaving open the question of whether they evolve together. We combine both perspectives for the Ye & scedil;il & imath;rmak basin, T & uuml;rkiye, using daily streamflow records (1954-2019) from 15 gauging stations. Trends in annual minimum and maximum flows at 1- to 90-day durations were assessed with four tests (Mann-Kendall, Spearman's rho, Innovative Trend Analysis and the Wilcoxon signed-rank test), and drought-to-flood transitions were identified at daily resolution by combining a variable-threshold (Q80) drought definition with fixed-threshold (Q98) flood peaks. Annual maximum flows declined strongly and coherently: 24-26 of 75 station-duration combinations showed significant decreases and essentially none increased, with 12 of 15 stations net-decreasing. Annual minimum flows declined more mildly and heterogeneously (24 significant decreases against 7 increases), with the signal concentrated in the shortest durations. Against this contraction in magnitude, the transition dynamics remained strongly structured. Of 235 transitions, 68% occurred in February-April with a March peak, and the median drought-to-flood time was 27 days. The probability of a flood within 60 days of drought termination ranged from 0.018 to 0.350 across stations and decreased moderately with mean daily flow (Spearman rho = -0.51). Flashiness trends were spatially organized, increasing along the central main stem and decreasing at the western and eastern margins. All transition results were robust across a 3 & times; 3 grid of drought and flood thresholds. The findings show that extreme-flow magnitude and transition dynamics are decoupled: shrinking flood magnitudes do not imply diminishing drought-to-flood hazard, whose seasonal window and spatial structure persist. Risk assessments based on extreme magnitudes alone would understate transition hazard, particularly along the regulated central basin and in springs following dry winters.