Predicting Inter-Urban Migration Flows in Iran: A Comparative Analysis of Gravity and Radiation Models

Rapid urbanization in Iran has caused interurban migration to play an important role in the dynamics of urban systems. Forecasting interurban migration flows plays an important role in migration policymaking, urban land use planning, urban management, and economic development. This study aimed to forecast interurban migration flows in Iran using the gravity and radiation model. The data used included the migration matrix of Iranian cities in 2011-2016 and was limited to 98 cities with a population of over 100,000 people. The gravity model showed that the population of the origin and destination cities has a positive relationship and geographical distance has a negative relationship with the volume of migration. In the radiation model, the probability of migration decreases indirectly with distance and increases directly with the number of intervening opportunities. The results of the study showed that the gravity model overestimated the volume of migration to metropolitan areas. On the other hand, the radiation model was more successful in predicting outliers and reducing large errors. However, this model underestimates long-distance migration flows, which is one of its limitations. Therefore, the choice of the appropriate model depends on the purpose of the analysis; the gravity model is more suitable for general patterns and the radiation model for specific and outlier flows. Also, to improve the predictions, it is suggested to use a combination of these two models and add socio-economic indicators