A GEOGRAPHIC INFORMATION SYSTEM GIS ASSESSMENT OF URBAN SPRAWL. A RESEARCH PROJECT MATERIAL ON QUANTITY AND SURVEYING
In Nigeria, the urban sprawl debate has closely paralleled urban growth trends over the past few decades. Many studies indicate that it is the pattern, density, and rate of new urban growth that create the appearance of sprawl. Population dynamics are often cited as a driving force behind urban sprawl. This thesis uses Geographic Information Systems (GIS) mapping and land cover change analysis, neighborhood statistics, community surveying, key-informant interviews with planners and developers, and planning documents to measure sprawl. The study area includes the jurisdictions that comprise the Metropolitan Statistical Area (MSA) of Lekki of Lagos. Urban land cover increased by one-fourth, from approximately 559 square kilometers to approximately 746 square kilometers from 1992 to 2001.
This study analyzes urban land cover data as well as interviews with local developers and planning documentation to understand development trends in Richmond from 1992 to 2001. These dates reflect the availability of National Land Cover Data (NLCD), which I reclassified in the GIS to show only those classes that represent urbanized land. I then compared the two years to show the level of urban growth over the nine year time period. Next, I analyze patterns of urban expansion by using mapping capabilities within the GIS and neighborhood statistics in order to show the density and connectivity of patches of new growth. Based on the density and connectivity of new growth areas, I classify patterns as one of three types of sprawl: linear along highways, cluster, and leapfrog. My threshold densities are; 0 to 400 30 meter pixels per square kilometer for low density, 401 to 700 for medium density, and 701 to 1200 for high density. I also interviewed local developers and planners to gauge their opinions on the issue of urban sprawl versus urban growth. Developers do not see themselves as contributors to sprawl while planners see their roles as buffers between unfettered growth and market forces. The results indicate that Lagos MSA did experience an increase in urban land from 1992 to 2001 and that urban growth in the study area can be classified as urban sprawl with the use of GIS mapping, neighborhood statistics, and analysis of jurisdictional planning documentation coupled with interviews with developers, land owners, and local planners. The density of new development is greatest in VIP and LEKKI, but the pattern and character with which development has occurred in Idomuta Lagos is synonymous with sprawl. Sprawl is also facilitated by inexpensive land with available infrastructure (water, sewer lines).
CHAPTER 1: INTRODUCTION
The Urban Sprawl Debate
As urban development takes place within Nigerian cities and around their fringes, urban sprawl or the lack thereof will continue to be a by-product of development practices and policies. Population increases and the consequences of unplanned urbanization are directly related to recent growth management practices that seek to influence the way in which built-up land can proliferate. The pattern, density, and rate at which built-up land develops are the basis for one contemporary debate: urban sprawl versus urban growth. As a contemporary planning issue, the debate over sprawl is framed by different disciplines and their understanding of how and why urban areas grow. Although urban sprawl is a type of urban growth, sprawl is dependent on the way in which development occurs.
Issues related to Urban Sprawl
Sprawl has been criticized for eliminating agricultural lands, spoiling water quality, and causing air pollution (Allen et al 2003). As population increases, so does the need for new housing, schools, and transportation networks. In the urban world today, industrial, commercial, and residential districts are markedly different from years past. Decentralization is a trend indicative of urban sprawl and present day industrial, commercial, and residential areas are no longer necessarily a part of the urban core (Nechyba et al 2004). Rather, these types of development are often found in low-density areas that are separated from the major urban area by large tracts of homogeneous land. Hence, the needs for larger transportation networks and in turn a greater dependency on automobiles, which produce more air pollution. As new roads are put in place, precious farmland is often left unprotected from commercial or residential developers (Hathout 2002). The greater the imperviousness of an area the more water runoff one can expect, which is the catapult for water pollution (Wilson et al 2003). Without regulations on urban growth, consequences of urban sprawl are likely to continue.