Characterizing the fabric of the urban environment: a case study of Salt Lake City, Utah

Urban fabric data are needed in order to estimate the impact of light-colored surfaces (roofs and pavements) and urban vegetation (trees, grass, shrubs) on the meteorology and air quality of a city, and to design effective implementation programs. In this report, we discuss the result of a semi-automatic Monte-Carlo statistical approach used to develop data on surface-type distribution and city-fabric makeup (percentage of various surface-types) using aerial color orthophotography. The digital aerial photographs for Salt Lake City covered a total of about 34 km² (13 mi²). At 0.50-m resolution, there were approximately 1.4 x 10⁸ pixels of data.

Four major land-use types were examined: 1) commercial, 2) industrial, 3) educational, and 4) residential. On average, for the areas studied, vegetation covers about 46% of the area (ranging 44-51%), roofs cover about 21% (ranging 15-24%), and paved surfaces about 26%(ranging 21-28%). For the most part, trees shade streets, parking lots, grass, and sidewalks. In most non-residential areas, paved surfaces cover 46-66% of the area. In residential areas, on average, paved surfaces cover about 32% of the area.

Land-use/land-cover (LU/LC) data from the United States Geological Survey were used to extrapolate these results from neighborhood scales to metropolitan Salt Lake City. In an area of roughly 560 km², defining most of metropolitan Salt Lake City, over 60% is residential. The total roof area is about 110 km², and the total paved surface area (roads, parking areas, sidewalks) covers about 170 km². The total vegetated area covers about 230 km².