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Track: Environmental Management
Jian Dai
University of California
Davis, CA 95616
Telephone: 916-754-6274/754-864
Fax:
E-mail: jjdai@ucdavis.edu
David Rocke
Using GIS To Evaluate Spatial Variations in Area Source Emissions
Area source emissions of air pollution have been traditionally estimated at the national level and then allocated to the states and counties. The spatial variations within a county have been largely ignored mainly due to the difficulty in collecting, processing, and analyzing the data at smaller geographic scales. With the increasing availability of digital data relevant to emission studies and the strong geocoding and analytical capabilities of a GIS, the spatial variations of emissions within counties are ready to be analyzed. This paper reports the procedures of implementing a GIS approach to allocating certain area source emissions of air pollution to subcounty units. The approach consists of three main steps. The first step is development of a spatial database. This includes identifying the emission producing facilities of interest in the study area, geocoding the locations of the facilities by address-matching with the TIGER/Line coverages, and developing other georeferenced data related to the
emission producing activities. The second step is disaggregation of larger areas such as counties into smaller zones. Usually, model grid cells are used as the basic spatial unit (BSU). The data coverages are then overlaid (unioned) with the model grid coverage. In step three, countywide emission estimates are allocated to the BSUs based on attributes of interest and spatial variations are evaluated. Often, predictive models can be developed by correlating emission producing activity with widely available data such as land use, road systems, and population census. If the models are carefully built, they can be applied to areas beyond the study region. The paper describes the methods for developing predictive statistical models for the purpose. The procedures and methods discussed in the paper are illustrated in an application, namely automobile refinishing emissions in the Sacramento modeling region, California. ArcInfo GIS is used for the application.
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