Studies on Prediction System of Pollutant Dispersion in Complex Terrain (IV)

Evaluation and Sensitivity Analysis of Dispersion Model

Abstract

Our previous papers presented a practical model to predict pollutant dispersion in a complex terrain. Thisstudy included dispersion experiments conducted in such region.
At first the field of wind flow in an area concerned is determined by modified potential flow model. Second the ground level concentration is calculated by a modified plume model.
This paper presents the effect of parameters in the plume dispersion model on the calculation in comparison with the observation of the experiments in Tochigi area.
In this model, the horizontal spread sigma;_y and vertical spread sigma;_z should be larger than those estimated from Pasquill-Gifford chart depending on atmospheric stability. In Tochigi area, sigma;_y and sigma;_z should be those corresponding to more unstable condition by 1-2 ranks. Furthermore sigma;_y should be diluted by about 3 times.
As the results, the effect of wind field model is more important than that of the dispersion model in view of the calculated concentration.