A Case Study in Urbanization and Environment

The materials were developed by Kenneth Foote and Shannon Crum, Department of Geography, University of Texas at Austin, 1996. You may use these materials for education and research, but please cite the Geographer's Craft Project, Department of Geography, University of Colorado at Boulder and the author. If you have comments or suggestions, please contact:  All commercial rights reserved.
This page is available in a framed version.  A Full Table of Contents is also provided.

The Research Problem

You are to consider how much of Austin's built environment is claimed by machine space (space which is set aside exclusively for the care and use of machines). Much of Austin's built environment is, for example, devoted almost exclusively to use by automobiles, buses, and trucks. Streets, parking lots, driveways, and loading ramps occupy well over half of all surface area in some parts of the city. But other machines and equipment occupy -- and dominate -- other space as well. Cooling towers for ventilation systems take up a notable amount of space, as does equipment needed to maintain telephone, electrical, water, and wastewater systems. Most people fail to perceive how much of the urban environment is given over to machines. Yet, machine space has tremendous effects. The concrete and asphalt used to pave streets and parking lots can change the microenvironment of the city. Average urban temperatures rise (the heat island effect) and concentrations of dust and particulates in the air increase. These changes are sometimes powerful enought to change patterns of precipitation over some cities. Machine space also adds to the impervious cover that alters the flow of rainwater through the urban ecological system. Finally, machine space can be a source of pollution as runnoff and wind sweep hydrocarbons, chemicals, and other pollutants into the water and air.

Your task is to explore how much of Austin's built environment is occupied by machine space and whether the amount of machine space is correlated with landuse and distance from the center of the city. The map to the right illustrates how you will present the data you gather. It presents a small section of Austin, zoned for single-family housing. The shaded areas designate machine space in that neighborhood.

Depending upon whether you work individually or in a group, you will gather information from between five and fifteen one-block sites within the City of Austin. You may pick your sites to include: (1) representatives of commercial, high-density residential, industrial, and low-density residential landuses in one precinct of the city to see how land-use affects machine space, or (2) representatives from one land-use category (commercial, residential, or industrial) at varying distances from the center of the city in order to determine whether there is a correlation between the amount of machine space and the distance of a site from the center of the city. Both options explore how the machine space varies across the entire urban environment. This project will provide you with experience in field surveying and field mapping. It raises issues concerning the effects of urbanization on the environment and environmental quality.

The Concept of Machine Space

The concept of Machine Space was introduced by Ronald Horvath in a 1974 Geographical Review article. According to Horvath, ". . . technology has been viewed largely as an aspatial phenomenon, and one of the major tasks here will be to translate technology into explicitly spatial terms. If geographers are to participate more fully in planning and monitoring future technological growth, explicit recognition of the spatial dimensions of technological change will be necessary. Machine space, or territory devoted primarily to the use of machines, shall be so designated when machines have priority over people in the use of territory. Automobile territory in modern American cities exemplifies the concept of machine space." (Horvath 1974, 167-168).

Between 1950 and 1970 one of the key spatial expressions of technological change was the rapid expansion of the Interstate Highway system and other improved roads. During this time the number of automobiles in the United States grew very rapidly. It is estimated that in 1950 there was 1 car for every 6 Americans. By 1970 that ratio had grown to nearly 1 car for every 2 people. At the same time, the number of highway deaths also grew significantly. Horvath's article appeared at a time when pedestrian spaces were being expropriated by cars. Machine Space was increasing at the expense of people space.

The degree to which the urban environment is given over the machines varies according to the predominant land-use. Residential areas tend to have less machine space -- industrial areas, more. But, all machine space is impermiable cover. The amount of machine space in a city has implications for air and water quality, as well as the quality of life in the city.

The interaction between society and environment is a fundamental theme of much geographical research. Cities are an excellent place to study these interactions. The process of urbanization results in large numbers of people gathering in relatively small areas. There the effects of habitation are concentrated and focused. Human effects on the atmosphere, lithosphere, hydrosphere, and biosphere are often so pronounced that cities can be said to create their own environments. They do this in a number of ways:

1) Effects on the Atmosphere and Climate

Cities create their own environments and, as they do so, they exert powerful effects on the atmosphere and climate. Among the most important of these are:

a) The Creation of Heat Islands

 Cities are made of concrete, asphalt, brick, stone, and steel. These materials absorb and reflect energy differently than vegetation and soil. They absorb more radiant energy and radiate this energy back into the atmosphere at different times through the day. The result is that cities are warmer than the surrounding countryside, sometimes considerably. Furthermore, cities remain warm well into the night when the countryside has already cooled.

This heat influences air circulation and patterns of precipitation.

b) Changes in Air Quality

 Human activities release a wide range of emissions into the environment including carbon dioxide, carbon monoxide, ozone, sulfur oxides, nitrogen oxides, lead, and many other pollutants. Some of these emissions are toxic and have claimed many lives in some cities when concentrations reached dangerous levels as in the "killer smogs" of London in the 1950s and 1960s. Others emissions such as carbon dioxide, act to trap heat in cities. Cities also release quantities of dust into the atmosphere, with effects like those mentioned next.

c) Changes in Patterns of Precipitation

 The dust and emissions released into the atmosphere alter patterns of precipitation over the cities and in areas downwind. Cities often receive more rain than the surrounding countryside since dust can provoke the condensation of water vapor into rain droplets. Dust carried downwind from cities and industry can increase rain in city shadows. One of the most notable of these rain shadows, the La Porte anomaly in Indiana, is diagrammed below.

2) Effects on the Lithosphere and Land Resources

Urbanization has similar effects on land resources. Natural land cover is disturbed as cities are built leading to:

a) Erosion and other changes in land quality

 Rapid development can result in very high levels of erosion and sedimentation in river channels.

b) Pollution

 Pollutants are often dispersed across cities or concentrated in industrial areas or waste sites. Lead- based paint used on roads and highways and on buildings is one such example of a widely dispersed pollutant that found its way into soil. But humans also bury tremendous amounts of waste in the ground at municipal and industrial dumps. These materials can severely contaminate soils. Even such commonplace items like gasoline storage tanks at filling stations have the potential to cause serious contamination. When this problem was discovered a decade ago, hundreds of storage tanks had to be removed and replaced with safer containers. The most extreme cases of industrial pollution, as at Love Canal in Buffalo, New York, have forced the abandonment of large tracts of land.

The first picture shows the University of Texas at Austin as seen from the Capitol before 1895. On the second picture a part of the University of Texas campus and downtown Austin as it is today can be seen.

3) Effects on the Hydrosphere and Water Resources

Urbanization has a great effect on hydrology, for a number of reasons.

a) Flow of Water into Streams

 As cities grow, natural groundcover changes dramatically. Natural vegetation and undisturbed soil are replaced with concrete, asphalt, brick, and other impermeable surfaces. This means that, when it rains, water is less likely to be absorbed into the ground and, instead, flows directly into river channels. Not only does more water reach the stream channels, but it arrives far more quickly after a storm. Natural vegetation slows run-off, concrete and asphalt speed the flow. The result diagrammed below indicates how urbanization speeds run-off and produces higher peaks of flow.

b) Flow of Water through Streams

 Higher, faster peak flows change streams channels that have evolved over centuries under natural conditions. The result is a spread of the channel vertically and horizontally to carry the extra flow. Rapid erosion of stream banks and down-cutting of stream beds occurs. When the existing stream beds cannot handle the increased flow, they flood the surrounding urban area, particularly development within adjacent floodplains.

 Flooding can be a major problem as cities grow and stream channels attempt to keep up with these changes.

Click here to see examples of flood damage in Austin.

i.) Methods for Controlling Flooding

 Often humans intervene to speed the flow of water through stream channels and to control erosion. Many different methods exist to control flooding and the flow of streams. Banks may be reinforced with plants, rock, or concrete retaining walls. In extreme cases, a stream may be "channelized," that is totally lined with concrete. Such channelization turns the stream into a very efficient culvert. Unfortunately, such channelization has the disadvantage of simply shifting the burden of the extra water flow downstream to other communities.

 Click here to see examples of flood control measures in Austin.

ii) Encroachment of Flood Plains

 As they grow, cities also tend to encroach on flood plains. These are low-lying areas that can hold and absorb overspill from stream during periods of high water. This encroachment of courses places humans in the way of floods. But encroachment also effects a watershed's ability to manage waterflow naturally. Excess flow may be kept out of floodplains by forcing extra flow downstream at higher speeds, with obvious consequences. Erosion and down-cutting will increase and the danger to downstream communities will increase.

c) Degraded Water Quality

 These changes in the flow of precipitation into and through urban watersheds holds a number of consequences of water quality.

i) Increased sedimentation

 An increased area of exposed and soils and higher runoff speeds means that more sediments are carried into local and downstream watersheds. This leads to increased rates of sedimentation.

ii) Pollutants in runoff

 As water washes across urban surfaces, it dissolves and carries pollutants into streams and rivers. Toxic chemicals, oil, and other pollutants are all deposited in the watershed, sometimes in sediments. Also, most cities use rivers to dispose of the affluent from sewage treatment. Nowadays, it is relatively rare in the United States for untreated sewage to be discharged into waterways since storm and sanitary sewers have been divided for the most part into separate systems, but it does happen from time to time.

Click here to see examples of pollution of Austin rivers.

5) The Interaction of Effects

One of the most interesting aspects of these processes is that they interact to reinforce one another. Atmosphere disturbances caused by urban activities increase precipitation, which increases erosion, which carries more sediment into river channels. Disturbances of land can cause disturbances of aquatic environments and increased levels of dust in the atmosphere. These cyclic and cumulative effects mean that urban ecological relations can become particularly complex. One change leads to another and another in a complicated, spiraling series of feedback loops.

6) How These Effects Develop

Sometimes it is easy to see how urbanization shapes the environment, particularly in peripheral areas were large suburban developments may consume hundreds of acres per year. But the impacts of urbanization begin early. Sometimes, the period of initial urban settlement produces the most radical changes in watersheds as tracts of land are cleared for the first time. Encroachment continues long beyond initial settlement as an almost continuous process. These maps of "machine space" show how the area of impermeable surfaces increases through time.

Click here to see examples of encroachment of Austin rivers and streams.

Techniques for Studying Machine Space

1. Select study sites using a map of Austin and zoning classifications. If you are working alone, select five one-block areas. Or, you may wish to work in a group of 3-4 people. In that case, you should select at least 15 sites. You may approach the study in a number of ways.

2. Acquire or copy the necessary base maps. Make sure the scale is sufficiently large that they are useful during your field reconnaissance surveys. You may need to enlarge street maps or zoning maps. There are digital maps (.dgn, .dxf. and arc.e00 formats) available on-line from the TWDB. Paper maps are available from a number of different sources. You might find street-level maps (available from the Texas Department of Transportation) and city zoning maps (available from the City of Austin) especially helpful.

 3. Field survey your study sites. Pace off the areas you have selected and record your findings on your map. Before you begin, you should set a lower level cut-off for your survey -- for instance, you might not include anything less than ten feet on a side. Remember that machine space includes automobile space (streets, driveways, parking lots, garages, service stations), ventilation systems, cooling plants, electric utility substations, water systems, etc.

a. Pace along a line-of-sight route across your study area.
b. Stop every three paces and observe your surroundings. Are you in machine space or people space? In some cases (a cooling plant, for instance), you will not be able to walk through the area. You should be able to locate and mark these areas on your base map, anyway.
c. Record your observation on your base map. Darken all those areas which you designate as machine space.
d. Pace additional transects to complete the coverage of your study area.

4. Calculate area of machine space. At this point, you have a couple of options. You may use the:

5. Make comparisons among your sites. If you are working in a group, this will involve combining everyone's data. If you chose to work with only one land-use, are you able to show a correlation between distance and amount of machine space? If you worked with multiple land-uses, does your map resemble the "Machine Space by Land Use" diagram in this module?

What to Turn In

 Finished maps of the machine space in your study area and an executive summary describing your findings.

Required Reading

Horvath, Ronald J. Machine space. Geographical Review 64 (1974): 167-188.

Further Reading

Arnold, Chester L, Jr. and C. James Gibbons.  Impervious surface coverage: The emergence of a key environmental indicator.  Journal of the American Planning Association  62 (1996) (2): 243-258.

Bunge, William W. and R. Bordessa. The Canadian Alternative: Survival, Expeditions and Urban Change. Toronto: York University. Atkinson College, Department of Geography, Geographical Monographs No. 2, 1975.

Detwyler, Thomas R. and Melvin G. Marcus, eds. Urbanization and Environment: They Physical Geography of the City. Belmon, Cal,: Duxbury Press, 1972.

Douglas, Ian. The Urban Environment. London: Edward Arnold, 1983.

Goudie, Andrew. The Human Impact: Man's Role in Environmental Change. Cambridge: MIT Press, 1981.

Laurie, Ian C. Nature in Cities: The Natural Environment in the Design and Development of Urban Green Space. New York: John Wiley and Sons, 1979.

Lounsbury, John F. and Aldrich, Frank T. Introduction to Geographic Field Methods and Techniques, 2nd Ed. Columbus, Ohio: Charles E. Merrill Publishing Co., 1986.

Lowry, William P. The climate of cities.  Scientific American 217 (1967) (August): 15-23.

Marx, Leo. The Machine in the Garden. New York: Exford University Press, 1964.

Mumford, Lewis. The Highway and the City. New York: Harcourt, Brace and World, Inc., 1953.

Schneider, Kenneth R. Autokind vs. mankind. New York: W.W. Norton and Company, Inc., 1971.

Spirn, Anne Whiston. The Granite Garden: Urban Nature and Human Design. New York: Basic Books, 1984.

Zuckerman, Wolfgang. End of the Road: The World Car Crisis and How We Can Solve It.  Post Mills, VT: Chelsea Green Publishing Co., 1991.

Last revised 2000.4.1. LNC.