Tracking Urban Change With Landsat

For helping communities across the United States stay up-to-date on their flood risk, the NASA/USGS Landsat satellites can take a bow. The Federal Emergency Management Agency uses Landsat images, which can illustrate urban changes, as a key indicator of sites where the agency should further investigate the flooding potential. With its archive of images capturing sprawling cities and new developments, Landsat can help FEMA track how building and construction is impacting an area’s landscape Earth-observing Landsat satellites have been capturing images of the planet’s surface since 1972. Landsat 8 is the newest satellite in the program, a joint effort between NASA and the U.S. Geological Survey. It launched Feb. 11, 2013, and collects more than 400 images per day. New and archived Landsat data are available free to the public over the internet – and researchers have put the data to a multitude of uses. One is called the National Urban Change Indicator, or NUCI, created by MacDonald, Dettwiler, and Associates, LTD. It’s the results from a process that mines Landsat images over a 27-year period to identify areas of “permanent change,” where soil has been paved over for parking lots or other concrete structures. NUCI results act as a red flag for FEMA, helping the agency focus its mapping efforts and budget. But if maps identify a high risk of floods for a certain community, residents can take action, including elevating houses, building flood barricades, and more.