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Urban Development

The southern California counties of Orange, San Diego, and Los Angeles are the top ranked counties in terms of area of topographic change polygons labeled as urban/built-up according to the NLCD. Orange County, the top ranked county, contains 72 change polygons (see figure below), most of which appear to be associated with new development. The detected change areas are located in the higher relief portions of the county where cuts, fills, or both are required to reduce the terrain slope enough to allow for housing and commercial building construction.

Orange County, California, is the top ranked county for topographic change related to urban development. Change polygons (blue = cut; red = fill) are overlaid on SRTM shaded relief.

The next two figures provide examples of where the cut and fill polygons associated with urban development are located on the landscape.

Topographic changes resulting from urban development in the Chino Hills area in Orange County, California (blue = cut; red = fill). The inset image (SRTM shaded relief overlaid with change polygons) provides locational reference. The arrow indicates the view direction (toward the east) for the larger perspective view. The area shown in the inset is about 11.6 km east-west by 10.7 km north-south.

Topographic surface changes resulting from urban development in Poway, California (San Diego County) (blue = cut; red = fill). The upper left image is NED shaded relief and the upper right image is SRTM shaded relief (both overlaid with change polygons). The arrow indicates the view direction (toward the south) for the larger perspective view. The area shown is about 5.9 km east-west by 3.5 km north-south.