Showing papers on "Urban climate published in 1980"

Urban Expansion and the Loss of Farmland in the United States: Implications for the Future

Abstract: As our cities and towns grow and decentralize, farmland and other rural lands are converted to urban uses. The loss of agricultural land to urbanization in this country has evoked little concern in the past. Because of the recent period of food price inflation and agricultural shortages across the world, however, some observers have begun to worry that the continued loss of farmland to urban uses may interfere with the United States' long-run ability to produce food and fiber for itself and for the rest of the world. (See Brubaker, Crosson 1977, Pimentel et al. 1975, 1976, Schiff. For alternative views, see Heady and Timmons, Gardner, and the U.S. Department of Agriculture 1974.) This concern becomes even more serious if one expects that, in the future, energy and other nonland inputs to agricultural production may become very expensive (and/or be in short supply) and the country may be forced to return to a more land-based form of agriculture. Because of the high costs associated with "reconverting" land back from urban to agricultural uses, it is important to consider if the continued loss of farmland to urbanization could exacerbate a possible shortage of productive agricultural land in the future. The above concerns point out the need to relate systematically the urbanization of farmland to future farmland needs and to analyze whether or not a future conflict is probable. In this paper, we begin to explore this question. It should be noted that this paper considers only the most direct effect of urbanization on agricultural production-the conversion of agricultural land to urban uses. However, the negative externalities caused by nearby urban development can also have important indirect effects on agricultural production. These include: (a) the idling of farmland in areas under extreme urban pressures (Berry 1976, Plaut, pp. 176-82) and over a wider geographic area, (b) the switchover to less capitalintensive forms of farming (Berry 1978, 1979). Thus, even though agricultural land is not converted to urban uses, potential agricultural production is lost. The reason for not including this loss in our analysis is that, presumably, under high demand pressures much of this idled and less intensively farmed land could be brought back into intense farm production.

New patterns of urbanization in Southeast Asia: an assessment.

Abstract: It is becoming evident that the urban-industrial pattern of economic development through which Korea and Taiwan have achieved substantial gains in distributed income will not apply to Southeast Asia. Instead a new pattern of urbanization is emerging in the core countries of the region: Indonesia the Philippines Malaysia and Thailand. Rapid improvement of infrastructure and expansion of agribusiness have created increasing demands for urban services in rural areas. This demand has stimulated the growth of the informal sector in older and larger cities the formation of an increasing number of rural service centers and the creation of new patterns of commuting and circular migration linking farm households with urban income sources. (Authors)

Climatic Impacts of Urbanization

Abstract: The land-use changes accompanying urbanization have an impact upon virtually all climatic elements as a result of perturbations to the pre-urban cycling of energy and mass by the city-atmosphere system. The paper illustrates how and to what extent these changes occur based on the results of observational studies. By considering the effects of the city upon the processes governing airflow, the water, radiation and energy balances, cloud development and precipitation some understanding is gained for the observed alteration to the pre-urban fields of wind, humidity, air temperature, cloud and rainfall. Direct impacts of land-use change are limited to the micro- and local climatic scales but those related to gaseous, aerosol and heat emissions contribute on all scales up to and including the global.

City Limits: Emerging Constraints on Urban Growth

Abstract: The author examines current trends in urbanization and the emerging contraints that could affect future urban growth particularly in the developing countries. Such constraints include the provision of urban food supplies energy costs and employment opportunities. Strategies for managing urban growth are explored (ANNOTATION)

Modeling the runoff process in urban areas

Abstract: In recent years, concern about the physical environment and its management has grown rapidly. This is reflected in the increasing attention given to the planning process. The growth and expansion of urban agglomerations represent a typical aggregation of some of man's activities having a marked environmental impact, such as air pollution, noise pollution, etc. Perhaps most vital among the different aspects of impact remains the water pollution. Urban hydrology studies portions of the hydrologic cycle, as modified by the presence of urban environments. Urbanization accounts for an increase in the total amount of runoff due to the increase of imperviousness of the drainage basins, thus aggravating the situation in flood‐prone areas. Equally important, the quality of the runoff waters is a concern, and more specifically its pollution effect on the receiving bodies of water, rivers, lakes, and groundwater recharge. The important recent research effort on the various aspects of these problems can be traced in ...

Relationships between aerodynamic roughness and land use and land cover in Baltimore, Maryland

Abstract: Urbanization changes the radiative, thermal, hydrologic, and aerodynamic properties of the Earth's surface. Knowl­ edge of these surface characteristics, therefore, is essential to urban climate analysis. Aerodynamic or surface rough­ ness of urban areas is not well documented, however, be­ cause of practical constraints in measuring the wind profile in the presence of large buildings. Using an empirical method designed by Lettau, and an analysis of variance of surface roughness values calculated for 324 samples averaging 0.8 hectare (ha) of land use and land cover sample in Balti­ more, Md., a strong statistical relation was found between aerodynamic roughness and urban land use and land cover types. Assessment of three land use and land cover systems indicates that some of these types have significantly different surface roughness characteristics. The tests further indicate that statistically significant differences exist in estimated surface roughness values when categories (classes) from dif­ ferent land use and land cover classification systems are used as surrogates. A Level III extension of the U.S. Geo­ logical Survey Level II land use and land cover classification system provided the most reliable results. An evaluation of the physical association between the aerodynamic properties of land use and land cover and the surface climate by nu­ merical simulation of the surface energy balance indicates that changes in surface roughness within the range of values typical of the Level III categories induce important changes in the surface climate.

Urban growth and urbanization in least-developed countries: the experience of Nepal 1952-71

Abstract: The authors attempt a reevaluation of both urban growth and the urbanization process in Nepal. Regional variations in the process and nature of urban growth and urbanization rates are identified and a distinction is made between the phenomena of urban growth (or growth of the urban population) and urbanization (or migration to urban areas). An attempt is made to identify factors affecting the urbanization process between 1952 and 1971 (ANNOTATION)

New Trends in European Urbanization

Abstract: The study discussed in this article specifically set out to ask whether recent American urban trends—de— concentration, growth of nonmetropolitan areas, stagnation or decline of larger urban areas, and regional shifts from frostbelt to sunbelt—had any parallels in Europe. The conclusion is that, overall, Europe does not offer many parallels except for an increasing tendency to core-ring decentralization. There is no movement to nonmetropolitan areas, except in France during the early 1970s, and indeed until that time some countries still tended to centralize their urban populations. The industrial heartland has continued to grow, and while the European sunbelt has also grown rapidly, the causes are different from those operating in the United States. Finally, in much of Europe—although not in Great Britain, the country where the trends are most like the American ones—larger urban areas have tended to show vigorous growth.