Urbanization of LDC’s Urban Land Use Models Ken Keller DHS - 2004 Introduction • Urbanization = % of population living in cities – 1950 -- 16%; – 1985 -- 30%; – 1995 -- 43%; – 2000 -- 47% World’s Population is now predominantly urban - 2005. Growth in BIG cities • > 1 million • > 4 million – 31 in 1950 – 5 in 1950 – 146 in 1985 – 28 in 1985 – 486 in 2025 – 114 in 2025 Very large cities are a feature of LDCs -- 17 of 23 megacities are in LDCs World Megacities Cycle of Urbanization Cycle of Urbanization • Stage 1 – Initial Stage: agrarian society, little surplus of production • Stage 2 – Acceleration Stage: beginnings of development, growth is concentrated in cities, rural-to-urban migration • Stage 3 – Terminal Stage: advanced stages of development, urbanization levels off with service economy and communications technology Urban Growth Processes • Rise of urbanization today follows beginning of s- shaped curve, but the ABSOLUTE INGREDIENTS ARE MUCH LARGER. It took NYC 150 years to gain 8 million people. 1980 - 2000 growth: – Dhaka -- 8 million Lagos -- 9 million – Bombay -- 10 million Karachi -- 7 million – Delhi -- 6 million Manila -- 6 1/2 mil. – Jakarta -- 7 million Urban Growth Processes, cont. • Lower levels of development • Higher population growth • No migration escape hatch • Future urbanization in Asia and Africa Sources of urban growth • Natural Increase accounts for 60% of growth. – High population growth rates – Young populations • Boundary changes and reclassification account for 8-15% of growth • Rural-to-urban migration accounts for 25-32% of growth. Many LDCs are already highly urbanized. • At low levels of urbanization, urban growth comes from migration, later from natural increase. • Africa = 33%; Latin America = 75%; Asia = 38% 3 critical issues • Overurbanization: Has urbanization outstripped the economic capacity to supply urban jobs? • Cost/benefits? Do the costs of large-scale concentration outweigh the benefits? • Primacy? Do megacities dominate the urban system at the expense of mid-size regional centers? Overurbanization? • Urbanization has always accompanied development and modernization. The pace of urbanization is surpassing the creation of new urban jobs. • The informal sector accounts for 1/3 to 1/2 of all employment in Third World cities. – Formal vs. informal sector – Why do people move to cities where there are not enough formal-sector jobs? Costs vs. Benefits of Concentration • Pros – Megacities allow country to concentrate its meager resources. – Megacities contribute disproportionately to the national income. Shanghai produces 11% of China’s industrial output and supplies 18% of its gov’t revenue; Lagos produces 50% of Nigeria’s manufactured goods; Mexico City produces 1/3 of Mexico’s GNP. – Huge markets -- economies of scale – Megacities offer a wide range of goods and services; they are a desired business location. • Cons – Inadequate water supply and sewage disposal – Poor air and water quality – Congestion and transportation problems – Political unrest -- “haves” vs. “have-nots.” – Inadequate housing -- 1/5 to 1/2 live in “informal shelters.” Urban primacy • When one city dominates the urban system. This is not the case in the US where NY, LA, and Chicago sit at top, followed by regional centers of Atlanta, Boston, Philadelphia, Seattle, Denver, and Phoenix, followed in turn by smaller cities and small towns and rural areas. • Many LDCs have urban systems that consist of the megacity and then much smaller towns. Consequences of missing regional centers. Examples of Countries With Primate Cities: Paris (2.2 million) is definitely the focus of France while Marseilles has a population of 800,000. Similarly, the United Kingdom has London as its primate city (6.9 million) while the second largest city, Birmingham, is home to a mere one million people. Mexico City, Mexico (9.8 million in the city; 16.6 million in the metropolitan area) outshines Guadalajara (1.7 million). A huge dichotomy exists between Bangkok (5.9 million) and Thailand's second city, Nakhon Ratchasima (278,000). Examples of Countries that Lack Primate Cities: India's most populous city is Mumbai (formerly Bombay) with 9.9 million; second is Dehli with 7 million, third is Kolkata (formerly Calcutta) with 4.4 million, and fourth is Chennai (formerly Madras) with 3.8 million. China, Canada, Australia, and Brazil are additional examples of non- primate-city countries. Utilizing the metropolitan area population of urban areas in the United States, we find that the U.S. lacks a true primate city. With the New York City metropolitan area population at approximately 20.1 million, second ranked Los Angeles at 15.8 million, and even third ranked Chicago at 8.8 million, America lacks a primate city. Rank Size Rule • In 1949, George Zipf devised his theory of rank-size rule to explain the size cities in a country. He explained that the second and subsequently smaller cities should represent a proportion of the largest city. For example, if the largest city in a country contained one million citizens, Zipf stated that the second city would contain 1/2 as many as the first, or 500,000. The third would contain 1/3 or 333,333, the fourth would house 1/4 or 250,000, and so on, with the rank of the city representing the denominator in the fraction. • While some countries' urban hierarchy somewhat fits into Zipf's scheme, later geographers argued that his model should be seen as a probability model and that deviations are to be expected. Firms and household compete for space in a way that maximizes satisfaction, within budget constraints, for every actor. Resulting in maximizing the “efficiency” of the urban space economy. Several assumptions to the model: City is on a flat, featureless plain Transport is ubiquitous; costs are only a function of distance City has a CBD is in the geographic center of the city Inhabitants are all “economic men” Above assumptions all imply an unstated one: Perfect competition Bid-rent theory: For all types of land uses, the most central sites will be the most attractive Given total space available in the city, the central sites are relatively few, so competition for them will be intense, and prices higher Different types of land users will place different financial evaluations on the utility of centrality. Each type of land user will have a different and distinct bid-rent curve that reflects the prices that type of users is prepared or able to pay for sites at different distances from the CBD. Putting the bid-rent curves together, we can see the overall bid-rent model shows that users with the steepest curves will capture the more central sites, while those with shallower curves --such as residences-- are left with more peripheral sites. Those with higher incomes will have steeper bid-rent curves and so end up nearer to the city center, while the lowest-income groups will end up on the periphery. Different households will bid for different-sized lots in different locations according to their relative preferences for living space versus the utility of accessibility. A trade-off between living space and commuting costs. Bid-rent model is also called the trade-off model. Land use is thus determined by the rent-paying ability of different economic functions in urban areas, such as retailing, industry and residence. The optimal location, where accessibility is optimal, is the central business district. All activities, including rural, would like to be located there, but they do not have the same capacity to afford this optimal location. Factors influencing the bid-rent curve: •Zoning laws •Different forms of transportation •Local variations in taxes •Cultural or regional preferences for housing type or tenure •Geography/topography and its affect on landscape views, affects of various industrial “run-offs”, e.g. being downriver or downwind. Limitations of the Bid-rent approach •Perfect competition may not exist •People do not always act “rationally” •Search for locations is constrained by time, money, imperfect information, other players •Land and property markets constrained by regulatory controls •Special interest groups affect land use and access The Burgess (Concentric Zone) Urban Land Use Model In 1925, E.W. Burgess presented an urban land use model, which divided cities in a set of concentric circles expanding from the downtown to the suburbs. This representation was built from Burgess's observations of a number of American cities, notably Chicago. According to this model, a large city is divided in concentric zones with a tendency of each inner zone to expand in the other zone. Urban growth is thus a process of expansion and reconversion of land uses. numerous criticisms: The model is too simple and limited in historical and cultural applications up to the 1950s. It is a product of its time. The model was developed when American cities were growing very fast in demographic terms and when individual transportation was still uncommon. Expansion thus involved reconversion of land uses. This concept cannot be applied in a contemporary context where highways have enabled urban development to escape the reconversion process and settle in the suburbs. The model was developed for American cities and has limited applicability elsewhere. It has been demonstrated that pre-industrial cities, notably in Europe, did not at all followed the concentric circle model. For instance, in most pre-industrial cities, the center was much more important than the periphery, notably in terms of social status. There were a lot of spatial differences in terms of ethnic, social and occupational status, while there were low occurrence of the functional differences in land use patterns. The concentric model Sector Model- Urban Land Use Representations A study done in 1939 by Homer Hoyt concluded that the land use pattern was not a random distribution, nor sharply defined rectangular areas or concentric circles but rather sectors. Communication axes are mainly responsible for the creation of sectors, thus transport has directional effect on land uses. We can see on the sector representation that Burgess transitional process is still part of land use changes, but there exist axes along which urban activities are oriented. Multiple Nuclei Model - Urban Land Use Representations Following Hoyt’s development of a sectorial city, C.D. Harris and E.L. Ullman (1945) introduced a more effective generalization of urban land uses. It was brought forward that many towns and nearly all large cities do not grow from around one CBD, but are formed by the progressive integration of a number of separate nuclei in the urban pattern. These nodes become specialized and differentiated in the growth process and are not located in relation to any distance attribute, but are bound by a number of attributes: Differential accessibility. Some activities require specialized facilities such as port and rail terminals. For instance, the retailing sector demands maximum accessibility, which is often different from centrality offered in the CBD. Multiple Nuclei Model - Urban Land Use Representations – Cont. Land use compatibility. Similar activities group together since proximity implies improved interactions. Service activities such as banks, insurance companies, shops and institutions are strongly interacting with each other. This can be defined as centripetal forces between activities. Land use incompatibility. Some activities are repelling each- other such as high quality residential and heavy industrial. This may be defined as centrifugal forces. Location suitability. Some activities cannot afford the rent of the optimal site for their location. They are thus locating at cheaper places, which are not optimal, but suitable for these activities. Harris and Ullman polynuclear model was the first to represent the fragmentation of urban areas, specialised functions as well as suburbanization. Although the urban experience in Latin America has varied because of diverse historical, cultural, and economic influences, there are many common threads that have prompted geographers to search for useful generalizations. One is the model of the intra-urban spatial structure of the Latin American city proposed by Ernst Griffin and Larry Ford, which may have wider application to cities of poor countries in other geographic regions as wells. The basic spatial framework of city structure, which blends traditional elements of Latin American culture with modernization forces now reshaping the urban scene, is a composite of radial sectors and concentric zones. Breakdown of Latin American city model: The Central Business District is the city's hub. Here one finds the central plaza, the principal church, and government buildings left over from colonial times, as well as the bulk of commercial activity, including high-rises, outdoor markets, hotels and restaurants. In the New model, the market is connected to the CBD, but distinct from it. The next zone is the Spine/Elite Residential Sector. This area contains all significant recreational and cultural activity not housed in the CBD. With easy access the CBD, this sector is also the first to obtain city services and utilities. It contains the city's most prestigious housing, occupied by the wealthy, or "filtered down" to the upper-middle class once the wealthy move to outlying areas. In the New model, this spine ends in a mall, a miniature business district of its own and a symbol of the neighborhood's prosperity. The Zone of Maturity is made up of large, solid homes, made of brick or concrete. This zone's population tends to be older and more established than the others', and socially middle or upper- middle class. All city amenities are available here, and the sector is regarded as a stable neighborhood. In the New model, a Gentrification zone encroaches on the area. This sector borders, both geographically and figuratively, between the elite and mature zones, creating a space for the upwardly mobile. Further out lies the Zone of In Situ Accretion. Of modest quality, the homes in this area are constantly under construction. Their owners improve the structures little by little according to their economic mobility and the availability of city services. This is a sector in constant transition. In the periferico are the Squatter Settlements. This zone has the worst housing conditions and fewest amenities in the city, with little vegetation and often no running water or electricity. Recent in-migrants to the city reside here in informal houses. Disamenity zones are dumps or other unused/unusable land. La Paz, Bolivia has grown to an enormous size, with sprawling shanty- towns spreading up the sides of the valley to the rim of the Altiplano Mountains. The city of 1.7 million is very much divided by class, with a distinctly small urban elite, a forever expanding, poverty-stricken lower class, and a newly emerging middle class. Over half of the population is Indigenous. La Paz has one main boulevard that runs the length of the city, following the natural canyon made by the Choqueyapu River, diagonally from the Northwest to the Southeast. Away from the main drag, streets climb steeply uphill, and many are cobbled or unpaved. Above the downtown skyscrapers, the adobe neighborhoods and the informal market areas climb toward the canyon's rim.