Integration of an air pollutant dispersal model with a geographic information system for urban environmental planning : y Vimut Prasertpunt

Air pollution from transportation results from the interaction of numerous factors related to economic growth, urban development and population dynamics. The problem is also affected by the topographical and meteorological characteristics of the area of concern. It is a major problem that threatens the well-being of inhabitants of large cities around the world. Because of the complex nature of the problem, it is difficult for policy planners and decision makers to foresee the consequences of the interactions and the resultant state of the urban air environment. At present, air quality models of various forms are used by responsible organisations to forecast and manage urban air quality. However, the models are so highly technical that it needs experts in the field to operate them. The outputs of these models are also intricate and difficult to comprehend at first sight. Most of all, air quality models do not explicitly handle the inter-relationship of the effects of changes in population and transportation. patterns on the urban air environment. This means that the planners and decision-makers do not have adequate and suitable tools for managing the problem of urban air pollution from transportation in cities. Thus, a decision support system that integrates population dynamics, transportation modelling and air quality modelling, and is able to portray their interrelationships is needed. Recently Geographic Information Systems (GIS) that provide the capabilities of database management system (DBMS), map manipulation and geographic display have been developed. In principle, the use of GIS should permit air quality in urban airsheds to be better modelled and visualised. The aim of this study was, therefore, to integrate the relevant models of population dynamics, transport modelling, air pollutant dispersion modelling and GIS into a system that could be used to assist decision making, policy planning and management of the urban air environment. A suitable integrated system was constructed and evaluated. Operation of this system showed that: It is potentially a powerful decision-support tool. It gives the user a holistic view of the effects of variations in transportation patterns and meteorological conditions on air pollutant concentration patterns. It also transforms the complex and highly technical process of data input, data preparation, and data manipulation needed for the calculation of air pollution concentration levels of an area of interest into a few user-friendly steps. It can also convey the comprehensive results of air pollutant dispersion through a simple but effective visual display; The integrated system can simulate the effects of different scenarios of future development projects and give good visual illustrations of the results. This means that planners will have clear pictures of what will happen if the projects are implemented, and can therefore prepare for the right course of action to deal with the anticipated effects. The project may then be modified, a better alternative may be selected, or protective measures can be implemented to alleviate the effects. The integrated system is a very powerful tool for planning and management of urban air environment because it provides both standard query and graphic query facilities for the system user. Additional databases of features necessary for the planning and management of the urban environment can also be established in the. system for processing and querying purposes if required. The problems remaining to be solved before the integrated system realises its full potential are the capabilities of the chosen air pollutant dispersion model and GIS package. It is recommended that any air pollutant dispersion model to be incorporated into the integrated system should be able to deal with chemical reactions as well as be able to follow movements of the air pollutant with the winds in the study area. It is also desirable that the GIS package have the capability of displaying movements of air pollutant in the study area