Measuring Urban Bulge: The Case of Settlement Density in Sacramento County

Since it is expected that density levels for sprawl are somewhere between the lowest densities of rural areas and the highest densities of compact urban areas, density classes four through seven would be most indicative of sprawl settlement. The choice for such a break is supported both by FRAP, which defines “urban” as Density Class 8 or greater (see FRAP metadata) and by Gillham’s definition of sprawl. However, since DenClass10 shows only levels of residential development it is not a complete “picture”. Areas that are commercially developed are falsely identified as class 1, alongside undeveloped or agricultural land. That explains the rose-colored shadings for commercial areas of downtown.

By integrating the NLCD and DenClass10, Develop10 is an attempt by FRAP to resolve the ambiguities and deficiencies of the former datasets and establish a comprehensive scale of human development for California. Where NLCD data was absent Density Classes are identical to Develop10 classes. Additionally where density classifications were 8 or above (DenClass10>=8) Develop10 classes are identical (DenClass 8,9, & 10 = Develop 8, 9, & 10): no modifications were made on the basis of NLCD data. Density classes that were less than class 8 were modified on the basis of NLCD classifications. If DenClass10 values were less than 8 and NLCD equaled low-intensity residential it became class 8 under Develop10 (DenClass10 < 8 and NLCD = 21, Develop10 = 8). Low intensity residential classification within an urbanized area affectively trumped housing density classes under FRAP’s schema, but not enough to receive the highest classification of Develop10. However, if DenClass10 values were less than 8 and NLCD equaled commercial or high-intensity residential it was effectively upgraded to a Develop10 Class 10, indicating the highest intensity use (DenClass10 < 8 and NLCD = 22 or 23, Develop10 = 10). Thus Develop10 affectively maintains classes 9 and 10 for the highest levels of urbanization, a sufficient criterion for the detection of sprawl settlement.



Finally, the communities of Elk Grove, Citrus Heights, Carmichael, and Rancho Cordova were selected for further analysis and comparison using the Develop10 dataset. With the exception of Carmichael (chosen as a “control” for the group), each of these communities has been recently incorporated, marking a maturing process in their growth trajectory from suburb to city. Do these newly formed cities demonstrate levels of development density characteristic of a city? Or are they merely low density suburbs with city status? On the basis of the comparative map below a set of conclusions were drawn.




Rancho Cordova, incorporated in 2003, shows predominantly classes of 8, 9, and 10 development density concentrated in the northwestern area. The large swath of undeveloped land, to the east (colored light rose) offers Rancho Cordova, projected by the Sacramento Area Council of Governments to be the fastest growing community in both housing, employment, and population growth within the next few decades, room to expand; and the established pattern of dense development absent leapfrog settlements suggests that the community is equipped to both effectively absorb, sustain, and benefit from the commercial and residential growth of the future. Citrus Heights, which incorporated as early as 1997, is covered mostly by dark blue shades and appears as the densest settlement in the sample group along with Carmichael, a census designated place that till now has not shed its suburban status for cityhood.

Interestingly, it is only Elk Grove, a city since 2000, which shows significant areas of low-density development. Most of this class 4 through 7 development lies on its eastern side, but even areas along its western corridor where the majority of development is clustered display only sparse patches of class 9 and 10. Admittedly, in the years since 2000, when the dataset was created, Elk Grove underwent explosive housing growth, and if a policy of structured growth and infill had been adhered to the result would be higher levels of development density than displayed by Develop10; so to test the reliability of this hypothesis, NAIP 2009 summer imagery was examined.





Despite the growth of the last decade, FRAP’s development assessment remains surprisingly accurate for Elk Grove: an overall case of low density despite new buildling. The significant gaps puncturing the landscape suggest a consistent pattern of leapfrogging. It is fair to conclude that the recent growth was sporadic and unplanned since no attempt was made to locate new settlements in absolute proximity to one another. The picture of poor development density for Elk Grove remains unchallenged.

In his book Sprawl: A Compact History, Peter Brugman, uses historical London as a paradigm case of urban growth. Brugman cites the flight of nineteenth century residents away from the squalor, contagion, and overcrowded center of industrial London to lower density settlements around the periphery. Overtime, as the process was repeated, the central density of London declined while the suburbs’ increased. The fact that such a process has been repeated elsewhere and at other times makes the “problem of sprawl” appear as a short term phenomenon - or rather phantom - with no teeth.

After Census 2000 a similar demographic shift was noted in the United States: suburbs located in the West reached levels of urban density and many had developed into cities. Examining FRAP’s Development Footprint, it becomes evident that the communities of Rancho Cordova, Carmichael, and Citrus Heights followed this suburban-urbanizing trend. So why worry about a sprawling Elk Grove? One should expect that overtime it too will follow course. Ironically, during the same 2000 Census, it was also noted that the suburbs of the South had become more sprawling. This suggests that suburban densification is not inevitable; nor is a low density pattern necessarily reversible.

Settlement patterns become “facts on the ground” that are difficult to change when future circumstances call for alteration, so that a certain pattern of low-density settlement accompanies a set of unknown costs purchased at a future date. Will existing patterns compromise a community's ability to accommodate natural population growth and the influx of new settlers? And if not what sort of tensions might arise between communities and between communities and the land as a result of such strains? Presently, there are other hidden costs to low density development. For example, in lower density areas residents generally pay the same price for water, sewer, and trash collections, though it costs the servicing agency much more to provide these services in terms of infrastructure and labor (Brugmann, 2009). Increased density contributes fundamentally to the economic and social efficacy of an urban community (ibid).

At this time, it hardly appears that Elk Grove is contemplating a change of course. For the past two years Elk Grove has been seeking to annex roughly 14,000 acres of pasture land and open space to the south and east of its present boundary. The move has come under some criticism from citizens and county officials alike who want the city to pursue growth within its current boundaries first. Unfortunately, data sets are not proscriptions: they simply mirror facts on the ground. Yet, if the data could talk it would undoubtedly say, “Elk Grove does not need more land, it needs to use the land it has more effectively.”

References

Bruegman, Peter. Sprawl: A Compact History. Chicago: University of Chicago, 2005. Print.

Brugmann, Jeb. Welcome to the Urban Revolution: How Cities Are Changing The World. New York: Bloomsbury Press, 2009. Print.

California Department of Fire and Forestry Protection. Development Footprint. (DEVELOP05_1).
CDF Fire and Resource Assessment Program, 2 Dec. 2005.

Firestone, David. “90's Suburbs of West and South: Denser in One, Sprawling in Other.”
The New York Times. Sprawl City, 17 Apr. 2001. Web.

Fulton, Bill. “Elk Grove: 7-Year-Old City Seeks Land for Expansion.” California Planning and Development Report. CP&DR, 30 Oct. 2007.

Gillham, Oliver. The Limitless City: A Primer on the Urban Sprawl Debate. Washington, DC:
Island Press, 2002. Print.

Kalb, Loretta. “District 5 Candidates Debate Elk Grove Expansion.” The Sacramento Bee.
Sac Bee Online, 3 May 2010.

Sacramento Area Council of Goverments. SACOG Information Center: Demographics. SACOG. n.d.

Appendices
The metadata accompanying the Development Footprint was considerably entensive, but by no means complete. The metadata in its entirety has been catalogued online by Conservation Biology Institute. See the full (metadata).