Historical diversion-shortfall characterization and verified operational modeling for off-farm operational risk zoning in Jarghuyeh Irrigation District, Iran

The study was conducted in the Jarghuyeh Irrigation District, central Iran, where surface-water delivery depends on diversion-dam inflows and is implemented through a manually operated open-canal network serving farmer cooperatives. This study develops a spatially explicit and methodologically transparent framework for assessing off-farm operational risk in irrigation districts exposed to diversion-flow shortfalls under manual canal operation. The framework combines statistical characterization of historical shortfalls with explicit hazard-threshold justification, calibrated and verified hydraulic–operational simulation, entitlement-based vulnerability assessment, and PCA-based consequence analysis with integrated consequence-sensitivity interpretation. It also includes a dedicated uncertainty discussion, risk-unit clarification, and non-stationarity discussion to support consistent interpretation of the mapped risk results. Final risk maps are produced by integrating hazard probability, vulnerability, and consequence at the level of individual irrigation units across the district. The framework reveals pronounced spatial clustering of vulnerability, consequence, and overall risk, including irrigation units that remain disadvantaged even under nominal inflow conditions and become critically exposed as diversion shortfalls intensify. By integrating empirical shortfall statistics, hydraulically consistent simulation, performance-based indicators, and multivariate analysis, the methodology offers a practical and reproducible tool for diagnosing weaknesses in manually operated surface-water distribution systems. The resulting risk maps indicate a systematic escalation from low risk (0–2%) under normal scenarios to extreme values approaching 35% under the most severe stress conditions, with approximately 65–70% of the irrigated area experiencing normalized operational risk-index values above 1.5% in high-shortfall scenarios. These patterns highlight the limited adaptive capacity of the existing manual operating system and provide an analytical basis for future evaluation of operational performance under changing climatic conditions. • Spatial risk framework integrates inflow shortfall, vulnerability, and consequence at cooperative scale. • Non-parametric inflow analysis defines hazard scenarios and associated risk probabilities. • Calibrated Integrator–Delay model reproduces drought-stressed delivery in open canal systems. • PCA-based consequence index integrates adequacy, dependability, and efficiency into one metric. • Bootstrap and Morris methods quantify uncertainty, threshold stability, and model robustness.