Urbanization of the landscape is an ongoing land use trend as more than 50 percent of the world's population will reside in urban areas in the next century. For example, during the timeframe from 1900 to 1990, the population of the Southwestern United States (Arizona, California, Colorado, New Mexico, Nevada, and Utah) increased by approximately 1,500 percent as compared with the entire U.S. population, which increased by only 225 percent. Human-induced land transformations are now a geomorphic agent roughly equivalent to natural processes in terms of the mass of soil and rock moved per annum. From 1970 to 1990, a national increase in population of 1 percent resulted in a 6- to 12-percent increase in land use. The land surface being transformed because of increased population has typically meant the proliferation of asphalt and concrete and the displacement of agricultural lands, forest lands, and wetlands. Population growth in Western U.S. cities has resulted in recreational use of lands which are more vulnerable to environmental damage and take longer to recover from the increased human traffic.

Land Transformations

The dominant land transformation is the transition of unsettled land to human settlement. Future urbanization may be constrained by the quantity and quality of natural resources available. However, future landscapes are also influenced by a region's terrain, land use zoning, areas protected from development, and accessibility to transportation. To analyze the effects of urban growth, the USGS has been collaborating with the University of California-Santa Barbara in the application of the Deltatron Land Cover Model (LCM) for predicting future landscapes. The purpose of the LCM is to predict the urban areal extent of future landscapes and visually represent the land mass that would probably be consumed by urbanization.

Urbanization

Continued urbanization of the Western U.S. will be a trend for the 21st Century which cannot be stopped. For example, the State of Utah's population took 113 years to grow to a total of two million residents, however, it will only take another 30 years for the state's population to double. Several southwestern states, for example, Arizona and New Mexico, are proposing municipal urban growth boundaries to contain urban sprawl, maintain habitat continuity, and reduce the human impact on the land surface. The USGS urban dynamics and global change research can help to identify which areas are most at risk of future urbanization and analyze the potential environmental and societal impacts of the resulting urban land transformation.