Sensitivity Study On Key Parameters Of CALPUFF Model

The environmental impact assessment system is a system to predict,analyze and evaluate the possible impact on the environment after the implementation of the project.The purpose is to prevent and reduce the adverse impact on the environment.Atmospheric environmental impact assessment is an important part of it,and atmospheric environmental impact prediction and assessment is an important issue and core content of atmospheric environmental impact assessment.In recent years,the status of atmospheric environmental impact prediction in environmental impact assessment is rising rapidly,and its basic tool is atmospheric diffusion model,one of which is CALPUFF model,which is one of the most widely used models by environmental impact assessment workers at home and abroad.CALPUFF model is a three-dimensional unsteady Lagrange puff diffusion model,which needs a lot of parameters to run.Therefore,if the input parameters of the model are set unreasonably,it will have a huge impact on the simulation results.In order to ensure that the input parameters can simulate the predicted concentration more accurately and effectively,this paper reveals the importance of model parameter setting by comparing the model operation results under different pollution source parameters(point source,non-point source,volume source),meteorological parameters and land use parameters,and further gives reasonable suggestions on parameter setting,so as to provide technical support for the practical application of CALPUFF model.The results show that among the three kinds of key parameters,the influence degree of the observed parameters on the prediction results,that is,the variation difference in the experiment,the pollution source parameters are 18.60% ～ 131.32%,the surface meteorological parameters are 3.17% ～ 10.38%,the land use parameters are 2.98%,4.93% and 34.31%,and the sensitivity degree is pollution source parameters > surface meteorological parameters > land use parameters;The pollution source parameters have the greatest impact on the model operation results,and all parameters have a greater impact on the prediction results;Among all the surface meteorological parameters,wind speed,station air pressure,relative humidity,temperature and cloud base height are sensitive parameters,while wind direction,total cloud cover and precipitation code are less sensitive parameters.The sensitivity order of the five sensitive parameters is: wind speed > temperature > relative humidity > cloud base height > station air pressure;Among the land use parameters,the sensitive parameters were surface roughness,noon reflectance and Bowen’s ratio,while the less sensitive parameters were soil heat flux,anthropogenic heat flux and leaf area index.The order of sensitivity of the three sensitive parameters was surface roughness > Bowen’s ratio > noon reflectance.This study is helpful for CALPUFF model users to use the parameters in their daily work,evaluate the errors caused by inaccurate parameters,and help EIA workers use the model better,which has practical significance.