Metropolitan areas in the UnitedStates are growing at unprecedentedrates, creating extensive urban land-scapes. Many of the farmlands, wet-lands, forests, and deserts that formedthe America of 1900 have been trans-formed during the past 100 years intohuman settlements. Almost everyonehas seen these changes to their localenvironment but without a clearunderstanding of their impacts. It isnot until we study these landscapesfrom a spatial perspective and thetime scale of decades that we canbegin to measure the changes thathave occurred and predict the impactof changes to come.

The U.S. Geological Survey's (USGS)Urban Dynamics Research (UDR)program studies the landscape trans-formations that result from the growthof metropolitan regions over time.Using sources such as historic maps,aerial photographs, and Landsat satel-lite data, USGS scientists first assem-ble retrospective urban land use data-bases that reflect several decades ofchange. These databases are then usedto analyze the effects of urbanizationon the landscape, and to model urbangrowth and land use change underalternative growth scenarios.

Land Use Change

Most major metropolitan areas facethe growing problems of urbansprawl, loss of natural vegetation andopen space, and a general decline inthe extent and connectivity of wet-lands and wildlife habitat. The publicidentifies with these problems whenthey see residential and commercialdevelopment replacing undevelopedland around them. Urban growth ratesshow no signs of slowing, especiallywhen viewed at the global scale, sincethese problems can be generally

attributed to increasing population.Cities have changed from small, iso-lated population centers to large, inter-connected economic, physical, andenvironmental features.

Urban growth and the concentrationof people in urban areas are creatingsocietal problems world-wide. Onehundred years ago, approximately 15percent of the world's population wasliving in urban areas. Today, the per-centage is nearly 50 percent. In thelast 200 years, world population hasincreased six times, stressing ecologi-cal and social systems. Over that sametime period, the urban population hasincreased 100 times, concentratingmore people on less land even as thetotal land devoted to urbanizationexpands. Yet the temporal and spatialdimensions of the land use changesthat shape urbanization are littleknown, even in the United States.

In the United States, policymakers andthe public continue to raise concerns

about the effects that uncheckedurbanization has on the landscape. In1998, more than 200 communitiesacross the Nation voted on, and thevast majority adopted, measures tomanage urban sprawl. The UDR pro-gram provides basic data, predictions,and perspectives to help in formingsound policies for guiding environ-mentally sustainable growth.

Mapping Land Use Change

Databases developed by the UDR pro-gram contain interpretations of urbanextent, transportation routes, waterfeatures, and other important landuses. Selected regional studies are cur-rently in progress across the Nation.Data source availability for eachregion, in conjunction with historicalsignificance, determines the time peri-ods that are mapped. Features areinterpreted from diverse data sourcesincluding historical topographic maps,satellite images, census statistics, andaerial photographs. The resulting tem-

Analyzing Land Use Change In Urban Environments

Nearly 80 percent of U.S. residents live in urban areas. This map, compiled from nighttime imagery acquiredby the Defense Meteorological Satellite Program, shows city lights for urban areas in red for the contermi-nous United States in 1995.

U.S. Department of the InteriorU.S. Geological Survey

USGS Fact Sheet 188-99November 1999Printed on recycled paper

poral database is a spatial record ofthe pace and extent of the urbaniza-tion process.

A temporal database can be visualizedas a sequence of maps, such as thoseshown above and on the next pages,or as computer animations. Sequentialmaps show urbanization as a staticpattern that changes with each timeperiod that is mapped. Animationsillustrate the temporal dynamics,revealing patterns and trends that arenot possible to discern from tabulardata or static maps.

Understanding Land Use Change

The geographic understanding of landuse change in urban areas is a keyaspect of the UDR program. By ana-lyzing a temporal database for spatialpatterns, rates of change, and trends,the UDR program can provide insightinto how cities have developed undervarying social, economic, and envi-ronmental conditions.

This analysis requires understanding aregion's land use history. Populationdata, timelines of historical events,and related information are all used toexplain the mapped changes.Population data are correlated withthe temporal database so that humanmovement can be tracked and fac-tored into these interpretations.Population increases suggest econom-ic growth and the availability of jobsin an area, and population declinessuggest a decline in livability or eco-nomic issues that cause people toleave a region. Timelines of pastevents and other historical compila-tions aid in identifying the issues thataffected the development of theregion.

In addition to gathering statistical andhistorical information, scientists musthave a physiographic understandingof the place and its greater region.Topographic features, climate, andadequate supplies of water and othernatural resources can limit or encour-age growth and change.

The existence and accessibility oftransportation routes have often dic-tated patterns of urban growth. Urbanareas that were established in the 18thand early 19th centuries were usuallylocated along waterways, reflectingdependence on shipping for the trans-port of goods and people. By the mid-dle of the 19th century, railroadsbegan to connect existing towns andspurred the growth of new urbanareas.

The post-World War II era saw notonly an increase in the population ofmost metropolitan areas, but also theemergence of a society dependent onthe automobile. The proliferation ofthe private automobile led to expan-sive development at the edges ofmany urban areas. The developmentof the Interstate Highway system inthe 1950's spurred the widespreadconstruction of roads. As road net-works expanded and became morecomplex, urban development fol-lowed. As in the past, most recenturban growth has occurred alongtransportation corridors.

The UDR program provides the dataand geographic information necessaryto document past land use change. Bylooking to the past, communities andregions are better informed and

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This time series documents urban change in the Willamette Valley region over 115 years. The background ineach map is a shaded-relief image. The red areas represent urban extent for each time period. The PacificOcean and the Columbia River are shown in blue. This study region extends from southern Washington southto Eugene, OR. Within Oregon, politically defined urban growth boundaries have been in place since theearly 1970's in an attempt to control urban expansion.

This preliminary interpretation of urban land usechange for Chicago-Milwaukee shows urban growthin 1955, 1975, and 1995. Each time period is repre-sented by a different color. Black shows the extentof urban growth in 1955, red represents 1975, andyellow represents 1995.

equipped to plan and prepare for thefuture.

Land Use Change Modeling

Historical land use patterns, togetherwith current trends in a region, areused to model future land use.Results from modeling urban growthand land use change can be used bythe public, land use planners, and pol-icy makers to anticipate and plan forthe future. Land use change modelscan also generate alternative land-scape predictions on the basis of dif-ferent land use policies and environ-mental constraints.

These land use change models usesimple parameters including presenturban extent, major transportationroutes, topography, and protectedlands. Other factors, such as employ-ment opportunities, land prices, andthe millions of personal decisionspeople make, are not considered inthis modeling approach. The primaryfocus of the modeling effort is toaccount for physical controls on landuse. Acknowledging the uncertaintiesof models, the USGS uses statisticalmethods to predict probabilities ofurbanization.

Impacts of Land Use Change

Urban Dynamics research in land-scape characterization, urban growthmodels, and geographic understandingprovides the data necessary for ana-lyzing the impacts of populationgrowth and land use change. Thisinformation can be used to analyzethe causes of urban congestion, pollu-tion, and loss of natural resources.Each of these impacts is linked tochanges in the extent of urban, agri-cultural, and forested lands, and (or)transportation systems.

Planners use Urban Dynamics data toevaluate environmental impacts, todelineate urban growth boundaries orservice areas, to develop land use zon-ing plans, and to gauge future infra-structure requirements. Traffic con-gestion, a common malady of urban-ization, is the result of urban growth,increases in population density, andout-dated transportation infrastructure.

By evaluating trends associated withland use change over time, solutionsto traffic congestion may be obtain-able.

Another specific application of UDRdata is the correlation of air pollutionrecords with the temporal database todetermine if control strategies forreducing pollution have been effec-tive. Many pollution control strategieshave been used in the past threedecades. Correlation between land usechange and pollution helpsresearchers establish positive or nega-tive trends that indicate whether pol-lution control strategies have beensuccessful. With this information, pol-icy makers, resource managers, andthe public can make appropriatechanges for the future.

Hydrologists can use Urban Dynamicsdata to evaluate new water sources forfuture urbanization and to analyze

water pollution – a problem commonto urban areas, industrial sites, andagricultural lands. The amount anddegree of water pollution in rivers,lakes, and bays can be predicted onthe basis of past and future trends inland use change. A study currentlyunderway in the Patuxent River Basinin Maryland focuses on the sources ofwater pollution over time. In thisstudy, temporal change maps ofurban, agriculture, and forest lands areused to identify and quantify historictrends in sediment and nutrient loadsin waters draining into theChesapeake Bay.

Geologists use data on land usechange to evaluate the availability ofbuilding materials, such as sand, grav-el, and cement. Geologists also usedata on existing hazards to correlatewith the UDR data to predict theimpacts of future natural disasters andthe potential damage they may cause.

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This series of maps shows more than 200 years of urban growth in and around the Washington, D.C. area.The background in each map is a shaded-relief image. The red areas represent urban extent for each timeperiod and the blue is Chesapeake Bay. Projections for 2025, made with a land use change model, showlikely areas of new urban growth in yellow (high probability) and in greens (light green is moderate proba-bility; dark green is low probability).

Policy makers can then use thesedamage or hazard projections to directfuture development away from themost at-risk areas.

Finally, biologists also use land usechange data to compile maps on habi-tats, species distribution, and landmanagement. Predictions about futureurbanization are critical to the protec-tion of ecosystems and the sustain-ability of communities.

Products

The UDR program provides temporalland use databases, analyses of landuse change, and landscape changepredictions. Databases for study sitescontain digital maps of urban extent,transportation routes, water features,and other significant land uses com-patible for use in geographic informa-tion systems (GIS). Digital animationsare available to help visualize thetemporal patterns inherent in the data.A land use change model and docu-mentation are also available.Interpretive papers and maps based onthe data and models are published in avariety of formats.

Study Sites

UDR projects are underway in themetropolitan regions of Washington,D.C., Baltimore, Chicago, Milwaukee,Portland, Vancouver, New York,Philadelphia, San Francisco, and LasVegas. Additional work is being donein the Detroit River corridor,California's Central Valley, the FrontRange corridor of Colorado, SouthFlorida, and in the Middle Rio GrandeBasin in New Mexico.

Collaboration

The UDR program is a joint activitybetween the USGS and the Universityof California, Santa Barbara. TheBaltimore-Washington study was alsosupported by the University ofMaryland, Baltimore County, NASA'sMission to Planet Earth, U.S. CensusBureau, Library of Congress,Smithsonian Institution, and MarylandHistoric Trust. We are actively seek-ing the participation of organizationsin new project areas as partners andclients.

Information

For more information on the UrbanDynamics Research program, pleasecontactWilliam Acevedo U.S. Geological SurveyAmes Research Center MS 242-4Moffett Field, CA 94035Phone: 650-604-5299Fax: 650-604-4680Email: urban@usgs.gov

Project descriptions, plans, and infor-mation generated by the program areavailable at

http://edcwww2.cr.usgs.gov/urban.

For information on other USGS prod-ucts and services, call 1-888-ASK-USGS, use the ASK.USGS fax ser-vice, which is available 24-hours aday at 703-648-4888, or visit the gen-eral interest publications web site onmapping, geography, and related top-ics athttp://mapping.usgs.gov/www/prod-ucts/mappubs.html.

Please visit the USGS home page athttp://www.usgs.gov/.

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This series of maps compares changes in urban, agricultural, and forested lands in the Patuxent River watershed over the past 140 years. The top series shows theextent of urban areas (red) along with agriculture (gold), which was at its peak in the mid-to late-1800s. Since 1900, the amount of agricultural land has declined asurban and forested land (green) has increased.