Impact of complex terrain on atmospheric dilution factor

Gaussian Plume model is widely used for atmospheric dispersion calculations. This model assumes infinite, flat terrain, and transport by wind, homogeneous in space and time. To predict concentrations at receptors in complex and elevated terrain Modified Gaussian plume model (Point Source Diffusion model) was used to incorporate complexity of the terrain. The point source diffusion model provides realistic estimate of dispersion of plume on elevated complex terrain. The dispersion parameters used in the complex terrain algorithm are the same as the point source dispersion parameters for simple terrain. Height correction is an important parameter in the Gaussian plume model for complex terrain. The effective height corrections are based on elevation of the terrain or terrain objects (Hills or valleys) with reference to stack height