Akademik Veri Yönetim Sistemi
THEORETICAL AND APPLIED CLIMATOLOGY, cilt.156, sa.10, ss.1-18, 2025 (SCI-Expanded)
Droughts are complex hydroclimatic phenomena with substantial environmental and socio-economic impacts, necessitating accurate and adaptable monitoring tools. While multivariate drought indices offer improved realism by incorporating interdependencies among variables, most existing methods fail to adequately account for seasonal variability in marginal distributions. This study introduces a novel copula-based framework for constructing the Multivariate Standardized Drought Index (MSDI), which employs month-specific best-fit probability distribution functions to improve marginal transformation and applies copula functions to preserve inter-variable dependence. The methodology is applied to two climatically distinct Turkish river basins offering a robust test across contrasting hydrological regimes. Results demonstrate that the use of monthly group-specific PDFs enhances the representation of seasonal patterns, while copula-based modeling captures basin-specific dependencies effectively. Compared to the empirical MSDIe, the proposed MSDI offers smoother temporal transitions and improved detection of drought extremes, particularly in the tails of the distribution. Furthermore, drought duration, severity, and recovery characteristics derived from the index more accurately reflect hydrological stress, underscoring its potential utility for ecological monitoring and water resource management in diverse climatic settings.