Modeling the dispersion of vehicular carbon-monoxide pollution in Kathmandu valley, Nepal: A CALINE4 approach combined with GIS Techniques
Abstract
Kathmandu valley is more vulnerable to air pollution than other rapidly growing Asian cities because of the bowl like structure of the valley and poor wind speed inside the valley. The main objective of this study is to model the dispersion pattern of vehicular carbon monoxide in Kathmandu valley by using CALINE4 software combined with GIS techniques. CALINE4 uses vehicular count, pollution and meteorological data to predict the carbon monoxide (CO) concentration. A typical day (15th of February 2007) is chosen to calculate 1-hour average CO concentration at the receptor points during peak hour (8:00 – 9:00 am). A road network extending from Maitighar to Koteshwor, which is approximately 4 km in length, is considered as the main road network. Ninety receptor points are created within the 500 meters buffer area of the main road network and CALINE4 is used to predict CO concentration at these points. The predicted CO concentration at the receptor points are then interpolated using K-Bessel universal kriging. The resulting map is reclassified to create ‘hot-spots’ where the areas are classified based on the predicted CO concentration. Root mean square error (RMSE) method is carried out to evaluate the model performance by comparing the predicted and observed CO concentration within 10 meters buffer from the study site. The RMSE value is found to be 0.77 and the accuracy of the model performance as 74%. Read entire article
