Adam Knoff
Intro to GIS
January 22, 2009
Creating a Regional GIS to Understand and Predict Urban Sprawl
As urban sprawl moves to the forefront of planners’ minds, so too does the need
to view the problem and devise a solution using GIS. Southern California has long been
an epicenter of urban sprawl. The lack of regional planning in the area has led to
seemingly autonomous communities built in close vicinity to one another. The end result
is a region focused on the automobile and lacking any continuity. In the Santa Barbara
region, also known as the South Coast, students and professors from the University of
California, Santa Barbara have been developing a GIS to understand urban sprawl and
create smart growth methods at the regional level.
In an article posted at
http://www.esri.com/news/arcnews/fall01articles/modelingtools.html entitled “Modeling
Tools for Santa Barbara Smart Growth Planning Supported with GIS,” the methods
behind this use of GIS are explained. Beginning in 1998 and still ongoing, the project
has sought to look at the South Coast, which includes all towns and cities crammed into a
narrow coastal plain between the Ynez Mountains and the Pacific Ocean, as an entire,
integrated region. Growing steadily in population since World War II, the South Coast
was quickly approaching “maximum build out,” as of 1998. The entire region was facing
housing affordability, transportation, and governance issues. However, the area had
never been recognized and studied on a regional scale.
The first step in the process was to design a regional GIS (REGIS) of the South
Coast. Using each communities’ zoning and community maps was the first step. After
digitizing these maps, the researchers needed to understand how the area had previously
grown, so historic aerial photographs dating back to the early 1900s were scanned into
computers (Due to the local aerospace industry and university resources, these photos
were abundant and easily found). Next, the researchers used ArcInfo 8 to create
georeferenced mosaics of the area dating back to 1929. They created seven mosaics at
roughly ten-year increments dating up to 1997, which served as the basis of the REGIS.
Additionally, using ArcInfo 7 and ArcView GIS 3.2, the researchers color-coded
the assessor’s digital parcel map, which, in combination with the infrastructure found in
the photo mosaics, helped them create a detailed land use map, which can be seen here:
QuickTime™ and a
decompressor
are needed to see this picture.
Source: http://www.esri.com/news/arcnews/fall01articles/modelingtools.htm
With the REGIS map created, the next step was to understand the different ways
in which the South Coast could grow over time. Using the SLEUTH Urban Growth
Model, different scenarios of South Coast growth were calculated and displayed using the
same REGIS. An example of an output is shown below:
QuickTime™ and a
decompressor
are needed to see this picture.
Source: http://www.esri.com/news/arcnews/fall01articles/modelingtools.html
In this output, “Yellow zones were urban in 2000. Light to dark pink show increasing
probability of urbanization by 2040. Community general plan regions are shown in green.
In this scenario, all land protection was removed, and only existing parks were protected
from urban growth” (esri.com, 2009).
The spatial and geographic aspects of this project are integral to the project’s
goals. You cannot plan for a region’s growth, or in some cases decline, without first
understanding the area as a spatial entity. Had the researchers foregone the GIS and
simply produced estimates of new housing and commercial development, new road and
transportation infrastructure, and loss of coastal and open space, it would not have had
the same impact. While numbers and estimates are important, and were most likely
included in the GIS’ associated attribute tables, the spatial images are much more
powerful.
Furthermore, understanding each communities’ proximity also helps planners
understand where there is an over or under-abundance of certain services and
development. Because each town was previously acting as a separate entity, the spatial
display illustrates areas where certain developments, infrastructure and services can be
reduced and possibly combined.
In addition to this project it would be useful to also see not just the models
produced by the SLEUTH program, but whether or not the South Coast produced a
regional plan, or smart growth initiative, and whether or not that plan incorporated GIS.
Because the foundation was already created it would seem obvious to create a regional
plan in this manner, but as history shows, planners do not always take the obvious or easy
route.
The South Coast REGIS project shows how GIS is helping planners address
classic planning techniques like regionalism using new technology. This approach helps
understand the problem in a highly visible, easily understood manner and will be integral
in the future of planning.
References:
http://www.esri.com/news/arcnews/fall01articles/modelingtools.html Accessed on
January 22, 2009