Long-term Urban Development: Austin and Portland 1992-2006

Population growth and urbanization in the United States can lead to unregulated urban development. We wanted to examine urban development by comparing two cities. Austin, Texas and Portland, Oregon are two relatively similar cities that have experienced growth in the past 25 years. They differ in growth patterns: Portland is governed by a boundary that prevents sprawl. By comparing the impervious surface development of the two cities, we hoped to examine the differences between regulated and unregulated urban development.

1. Using the online USGS Multi-Resolution Land Cover Consortium, we downloaded land cover TIFF files and elevation data for the cities of Austin and Portland for the years 1992, 2006, and 2001. 2. TIFF files were added to ArcGIS to display the 16 Land use categories defined by the USGS. These files were converted to polygons using the raster to polygon conversion tool. The gridcode was used to categorize land use into water, developed open, low, medium, and high intensity areas. We symbolized the developed land in shades of red.3. Elevation data was used to display a background hillshade layer. The hillshade was created using Arctoolbox and spatial analysis tools. We symbolized the hillshade underneath the polygon layer.4. The Austin and Portland city boundaries were then downloaded online and added to ArcGIS. 5. Developed land, Hillshade elevation, and city boundaries were symbolized to display long-term urbanization in Portland and Austin, then exported as JPEG files and added to our poster.

Maps of Austin and Portland form 1992, 2001, and 2006 show accelerating trends in urban growth. A larger difference in total development can be seen between 1992 and 2001. Development is relatively spread out compared to Portland.

We can conclude that urban development has increased in the time period of 1992 – 2006. The development in Austin has expanded beyond the city limits. In Portland, the urban growth is contained by the boundary. A future study could attempt to quantify the ecological disturbance associated with urban growth in Austin and Portland.

USGS Online Data Resources: http://www.mrlc.gov/viewerjs/ Portland Shapefile: http://rlisdiscovery.oregonmetro.gov/

Austin Shapefile: ftp://ftp.ci.austin.tx.us/GIS-Data/Regional/coa_gis.html

Figure 4: Portland 1992 Figure 5: Portland 2001 Figure 6: Portland 2006

Figure 1: Austin 1992 Figure 2: Austin 2001 Figure 3: Austin 2006 Results Introduction

Methods

Conclusion

References

A Study By Conner Bradley, 2014