Improving Resolution of Census Data in Metropolitan Areas using a Dasymetric Approach: Applications for the Baltimore Ecosystem Study

Abstract

A dasymetric map is a type of thematic map where boundaries are altered by the distribution of other phenomena. In dasymetric maps, administrative or enumeration boundaries are redrawn to better represent the distribution of data classes. Dasymetric mapping methods can improve the resolution of historical and present day census data. Using data collected for the Baltimore Ecosystem Study, I use the dasymetric approach to remap the distribution of census data based on residential land use. By overlaying census boundaries with land use and land cover information in a GIS database, census data can be partitioned into places where, from the land use information, we know people live. This method is particularly helpful in parts of the city and suburbs where residential land use is uneven, such as new subdivisions or industrial neighborhoods. This approach can also be employed to improve the spatial resolution of historical data, typically collected at coarse resolutions. I demonstrate with a case study of the Greater Baltimore Region that dasymetric mapping is also an effective method for environmental equity analysis. I conclude with some promises and limitations of this method for urban ecological research.