System Dynamics Analysis of Wheat- and Corn-Based Food Supply Chains for Strengthening Food Security

Abstract Food security in grain supply chains emerges from the simultaneous interaction of physical availability, economic access, utilization, and stability, and evaluating isolated policies without accounting for system feedbacks and delays can lead to misleading results. This study aims to represent the dynamics of wheat and corn supply chains in an Iranian industrial holding and to conditionally evaluate the effects of trade policy, a world-price shock, and logistics-infrastructure development. A system dynamics model was developed for 2020–2035 with a semi-open boundary; wheat inventory, corn inventory, strategic reserves, and production capacity were modeled as stocks, while production, imports, consumption, losses, investment, and depreciation were modeled as flows. A composite food security index was constructed from the four dimensions of availability, economic access, utilization, and stability with equal weights, and the sensitivity of results to the weights and key parameters was examined. Numerical reconstruction of the 72-month series in the validation chart contained in the original file yielded MAE = 7.46, RMSE = 9.65, MAPE = 13.01%, and Theil's inequality coefficient U = 0.078. The 2035 index values for the baseline trend, tariff reduction, world-price shock, and dry-port development are 99.06, 104.02, 108.97, and 118.88, respectively. Nevertheless, the stability of wheat and corn inventories across scenarios indicates that a substantial share of the index differences is generated through prices, profitability, capacity, and logistics efficiency; therefore, the results should be interpreted as case-study evidence conditional on the model assumptions, rather than as direct estimates for the country as a whole. The findings emphasize the need to evaluate cost, implementation time, distributional effects, and uncertainty simultaneously in food-chain resilience policies. JEL Classification : Q18, , L91, , C61, Q11