Research Information System
Earth Systems and Environment, 2026 (ESCI, Scopus)
Rainfed agriculture in semi-arid regions like East Azerbaijan Province, Iran, faces significant challenges due to climatic variability, necessitating robust risk assessment frameworks to inform sustainable management. This study employs a copula-based approach to model the multivariate dependence between rainfed wheat yield and key climatic variables (precipitation, temperature, and relative humidity) across East Azerbaijan Province. Using the Growing Degree Days (GDD) method, growing periods ranged from 250–296 days, with reference evapotranspiration () estimated at 3.11–4.53 mm/day via Penman–Monteith-FAO56, crop evapotranspiration () at 432–709 mm/growing period, and effective rainfall (FAO method) at 41–73 mm/growing period, highlighting substantial spatial variability in water availability. Best marginal distributions (Normal, Weibull, Cauchy) and multivariate copulas (Clayton for most stations, Gaussian for Tabriz) were selected based on AIC, BIC, and RMSE. From 27 scenarios derived from the 25th, 50th, and 100th percentiles of climatic variables, probabilities of below-average yields ranged from 0.92–29.99%, with return periods of 2–109 years. Low risks were observed under Scenario 1 (0.92% in Ahar, 109-year return period), while high risks occurred in scenarios with elevated temperature (Scenarios 18, 24, 26: up to 29.99% probability in Mianeh, 19.2-year return period). Spatial mapping revealed Ahar’s resilience and Mianeh’s vulnerability. Model robustness was confirmed through leave-one-out cross-validation (LOOCV; mean predictive log-likelihood: -2.51 to -4.22, highest in Mianeh) and bootstrap 95% confidence intervals for return periods, quantifying uncertainty from the limited record. These findings provide a framework for targeted interventions, emphasizing drought-tolerant cultivars and water-conservation practices to enhance rainfed wheat resilience.