Jun 9, 2017

Changes in Exposure to Flood Hazards in the United States

Yi Qiang, Nina S. N. Lam, Heng Cai and Lei Zou
Annals of the American Association of Geographers
  • Conducts a national, county-based assessment of the changes in population and urban areas in high-risk flood zones from 2001 to 2011 in the contiguous United States
  • Uses the U.S. Federal Emergency Management Agency's (FEMA) 100-year flood maps, land cover data, and census data to extract the proportion of developed (urban) land in flood zones by county at the two time points, and calculates indexes of difference
  • Identifies hot spots of increase in urban area in flood zones and estimates the population in flood zones from the land cover data
  • Results show that in 2011, an estimate of about 25.3 million people (8.3 percent of the total population) lived in high-risk flood zones
  • Results show that nationally, the ratio of urban development in flood zones is less than the ratio of land in flood zones, implying that Americans were responsive to flood hazards by avoiding development in flood zones
  • Provides important baseline information on the spatial patterns of flood exposure and their changes from 2001 to 2011