Physical modeling for emergency planning support: Gas dispersion simulations in urban and rural areas

Abstract

Protecting public health and ensuring environmental safety are essential for sustainable urban development, especially in the vicinity of industrial sites. This study evaluates the performance of ISC3, a Gaussian gas dispersion model, by comparing its predictions with wind tunnel data for idealized urban and rural environments. The analysis shows that the ISC3 model significantly underestimates pollutant concentrations in urban areas, particularly along transversal streets near the source, e.g. due to its inability to accurately represent complex flow patterns such as recirculation zones. This underestimation poses a risk to emergency preparedness and urban planning. In contrast, in rural areas, the ISC3 model generally overestimates concentrations, but this overestimation remains within acceptable limits, providing a more reliable prediction. The case study concludes that while Gaussian models are useful for initial assessment in areas of low roughness, their accuracy decreases in complex urban environments. For more accurate predictions in such environments, wind tunnel modelling is recommended as a more robust tool for site-specific risk assessment for land-use planning and emergency preparedness purposes.