Can we plan to protect our environment? Spreading ...€¦ · Can we plan to protect our...

Can we plan to protect our environment? Spreading urbanization in the state of Louisiana

I. Maret & H. Blakeman College of Urban and Public Affairs, University of New Orleans, USA

Abstract

Accused of being the dark side of the American Dream, sprawl illustrates how spreading urbanization can be costly for our environment, our society and our future. In most studies, sprawl is approached broadly and limited to the edge of large and fast-growing urban areas. Current analyses underestimate the extent of the development of new urban forms in previously rural areas relatively far from the urban core, especially in slow-growing urban regions. Sprawl is endemic to small towns as well as large cities, spurred largely by interstate and highway bypasses. This paper suggests that sprawl should be scrutinized as a complicated and diverse land use change. It explicates with GIS and remote sensing approaches the variety and complexity of urban sprawl regions in Louisiana, using population and land use data. This research focuses on the characteristics of new urban forms in the region of New Orleans, Louisiana (LA), looking particularly at St. Tammany Parish. This parish grew at a faster rate in the nineteen-nineties than any other parish in Louisiana. Most of the growth occurred in unplanned, uncoordinated clusters or in unincorporated areas outside of existing cities. This paper examines the consequences of sprawl on the environment, focusing on the link between types of urbanization and the loss of wetlands in St. Tammany Parish, LA, from 1982 to 2000. It then analyzes the diversity of smart growth policies needed to deal with these sprawling situations. Keywords: sprawl, sustainable planning, wetlands, urban growth, smart growth policies, Geographic Information Systems (GIS).

© 2005 WIT Press WIT Transactions on Ecology and the Environment, Vol 84, www.witpress.com, ISSN 1743-3541 (on-line)

Sustainable Development and Planning II, Vol. 1 451

1 Introduction

Sprawl, the major urbanization pattern of the 20th century, not only occurs on the edge of major fast-growing metropolitan areas like Houston and Atlanta, but also in slow-growing urban regions. Hence, this fragmented urban land use landscape is witnessed in the relatively slow-growing urban region of New Orleans, Louisiana. The New Orleans metropolitan area (MSA) is composed of 8 parishes (counties) surrounding Lake Ponchartrain (Figure 1). Table 1 shows that the central parish in the region, Orleans Parish, lost population between 1990 and 2000, while most of the other parishes experienced some growth.

Figure 1: Population in New Orleans MSA.

Between 1990 and 2000, St. Tammany Parish experienced the fastest growth within New Orleans MSA and in the entire State of Louisiana, as its population grew by 32.4% and another 8.6 % between 2000 and 2003. Most of this growth took place outside of towns. St. Tammany’s new constructions are usually composed of piecemeal subdivisions and isolated malls standing outside the geographical jurisdiction, and therefore out of the planning and regulatory influence of local governments.


452 Sustainable Development and Planning II, Vol. 1

Table 1: Population trends in New Orleans.

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St. B

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St. J

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Population trends in the parishes ofNew Orleans MSA, 1990-2000

Population 1990 Population 2000

Barras, et al. [1] found that at the same time, the State of Louisiana is losing 24 square miles of wetlands each year. Originally considered as wastelands, wetlands have since been proven to be productive habitats for flora and fauna. In Louisiana alone, 50 % of the residents live in coastal parishes, according to the US Census Bureau [2]. Since the majority of Louisiana’s wetlands are located in the coastal zone, this coastal urbanization further stresses these sensitive wetland habitats. Researchers working on sprawl often focus on its definition and its localization. This work will first analyze, with a GIS approach, the patterns of urban growth in St. Tammany Parish. We will then investigate the relationship between types of urbanization and the degradation and destruction of very valuable natural resources, wetlands. Finally, the analysis will frame a discussion on possible policy responses.

2 Why should we study spreading urbanization and its consequences on wetlands loss?

Unplanned urban spread began to be a major affliction for many cities in the 20th century. Christened “sprawl,” this urban growth pattern is accused of being costly not only for local governments, but also for public health and the environment. Malpezzi [3], Ewing et al. [4], Gordon and Richardson [5], Galster et al. [6], are attempting to capture the nature and extent of the new urban landscape. Characterized by Harvey and Clark [7] as a spreading urban pattern at declining densities, it has the distinction of consuming land for urban purposes at a pace exceeding the rate of population growth. Ewing states that it uses excessive space in a disorderly manner and at declining densities, with a



leapfrogging behavior, jumping into the hinterland, and forcing infrastructures to catch up. Downs [8] cites some of its consequences, among them the fragmentation of open space, the automobile dependence, and the increase of air pollution. Few researchers are investigating the relationship between sprawl and the loss of wetlands. Ehrenfeld [9] confirms the link between land-based urbanization and the destruction of wetlands, decline in water quality and food chain contamination in the Gulf of St. Vincent, Australia. The federal Clean Water Act (CWA) [10] defined “wetlands” as those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs and similar areas. These habitats are vital for protecting the environment and public health. Some of their assets are to filter pollution, purify our drinking water, recharge groundwater aquifers, and absorb floodwaters. This last quality is particularly important in flood-prone areas like South Louisiana. In 1999, the General Accounting Office [11] estimated that approximately 290,000 acres of wetlands are nationally lost per year. National Research Council data [12] shows that since the 1700s, New York has lost more than 60% of its estimated original 2.562 million acres of wetlands. We present in this analysis the relationship between types of urbanization and the loss of wetlands in St. Tammany Parish between 1982 and 2000. Since sprawl thrives on new highway construction, we will also assess the influence of roads on wetland destruction.

3 Sprawl and wetland destruction in St. Tammany Parish

3.1 Localization of wetland loss in St. Tammany Parish

Though the central and northern parts of Louisiana are still somewhat rural, the southeast portion of the state has become increasingly urbanized, especially along the two corridors of Interstate 10 and Interstate 12. Most of Louisiana’s large cities are in or near the Coastal Zone, which is influenced by the Gulf of Mexico and contains the majority of Louisiana’s wetlands. Lafayette, Baton Rouge, New Orleans, Hammond, Slidell and Mandeville are all in or adjacent to the Coastal Zone. Many of the urban regions of the Coastal Zone are expanding their impervious surface area in gargantuan bites, resulting in an increasing pressure on wetlands in and near urban areas. St. Tammany Parish, in the period 1982 and 2000, most of which is in the Coastal Zone, provides the most dramatic example. Figure 2 illustrates the urban and habitat changes between 1982 and 2000. Within these 18 years, urbanization has exploded. In the western portion of the parish, the most radical growth took place in the Mandeville/Covington area. The area north of Mandeville and the strip between Highway 190 and Interstate 12 show the most dramatic increases. The City of Mandeville itself experienced a 48% increase in population between 1990 and 2000. As a result, the urban



regions of Mandeville and Covington are progressively merging and the area is losing its rural identity. Mandeville also expanded along the coastline of Lake Ponchartrain, building on upland forest, wetland forests and marshes. In the Slidell area, less dramatic patches of growth occurred between Interstate 12 and the Pearl River wetland area. Most of the growth is occurring directly to the east of the city, along Highway 190. This expansion of the built environment continues above Interstate 12, hugging the edge of the Pearl River wetlands to the north. Despite clustering around incorporated areas, it is clear that spreading urbanization did not ignore St. Tammany’s outlying extremities. The unincorporated areas between Mandeville, Madisonville, Covington and Abita Springs experienced major increases of their urban landscapes. The remote sensing imagery illustrates the highly fragmented pattern of urban development.

Figure 2: Urban change in St. Tammany Parish between 1982 and 2000.

3.2 Spatial patterns of wetland loss

According to the Lake Ponchartrain Basin Foundation [13], between 1982 and 2000, 11,000 acres of marsh and nearly 34,000 acres of wetland forests were destroyed. In areas where the wetlands are not being eliminated, urbanization



butts up to the edge. While this does not destroy the wetlands, urban pressure can degrade wetlands over time, rendering them uninhabitable for flora and fauna. Figure 3 presents the localization of wetlands converted to urbanization between 1982 and 2000. The comparison between Figure 2 and Figure 3 illustrates the relationship between scattered urbanization and the destruction of marsh and wetland forest.

Figure 3: Wetlands converted to urbanization between 1982 and 2000.

Most of the destruction of wetlands is located in or next to urbanized areas. The conversion pattern is highly patchy, demonstrating the fragmentation of the urbanization. The wetland division also follows the main road corridors, especially in the northern part of Slidell.

4 Does sprawl lead to more wetland loss?

Many researchers offer methods, indexes, and models to quantify sprawl. Mapelzzi and Guo [14] conduct their analysis at a specific time. Hess et al. [15], and Galster et al. [6] focus their research on the study of the edge of major



metropolitan areas. Most studies use census data at the tract or county level to run their investigation, sometimes adding remote sensing data. As sprawl is multifaceted, we did not limit our study at the adjacent proximity of the central city. Harvey and Clark [7] admit that sprawl is a contemporary urban growth pattern, unsustainable over time, best pictured by trends in population density. We used population data from the 1990 and 2000 census, at the block level, to increase accuracy and precision. The census defines “urban” as any contiguous block of greater than 1000 people per square mile or 390 people per square kilometer. We used ArcView spatial analyst to create 200-meter grids for 1990 and 2000, which can be manipulated directly at the map level. We individualized different types of urban processes related to trends in densities. We note that potentially sprawling areas in St. Tammany Parish are areas that encounter low population density in 2000, while having a population density growth between 1990 and 2000 above the parish average: eqn (1).

PSj = [Xj < ZLD < Luj] ∩ [ISj >XChange ij] (1)

Xi= Mean Population Density in year “j”

ZLD = Zone of Low Density (<390)

Luj = Limit Urban (Lu < 390 pop./sq. km) in year “j”

ISj: Intensity of Sprawl

XChange ij = Mean Density Change from year “i” to year “j” (>20)

∩ = indicates that both conditions need to be satisfied for places to be

considered part of the urban sprawl

Figure 4 shows that potentially sprawling areas (low density and population gain) are not limited to the edge of the central city of New Orleans (in Orleans Parish), but enter deeply into the hinterland, encroaching on natural habitats. The fragmented landscape of the northern part of St. Tammany Parish testifies to an invasion of new urban scenery and lifestyle in previously rural areas. These trends in density reflect the residential housing construction patterns witnessed in the spreading areas. Many reasons can explain the tendency for development outside of incorporated areas. Among them, we can assert that undeveloped or underdeveloped land is likely more readily available and less expensive outside of cities. Second, developers try to escape municipal land use control. Finally, homebuyers try to fulfill the American dream and prefer to live in a rural atmosphere far from the problems of the inner city. Therefore, they tend to locate outside of city limits on large lots. We see, in Figure 4, a critical increase in potentially sprawling areas in the south of Slidell, near bridge connections to Orleans Parish. It is likely that people live in St. Tammany Parish and commute to Orleans Parish, to work in New Orleans’ city center. The potentially sprawling areas are also heavily present between Covington and Mandeville and on the eastern side of Mandeville. They are also closely linked



with roads and highways, especially US 190 between Mandeville and Slidell, as well as US 10 between Slidell and Pearl River and to the north. Luis Martinez from the Ponchartrain Institute for Environmental Sciences created a model with ERDAAS Imagine to understand the relationship between wetland loss and highways. We looked at wetland loss from 0.5 miles from a primary road to 2 miles. The results confirm the close connection between habitat change and roads, as most of the wetland loss between 1982 and 2000 occurred within 0.5 miles of a primary highway.

Figure 4: Potentially sprawling areas in St. Tammany Parish.

5 What mediation can be used to protect wetlands while expanding planned urban growth?

5.1 Attempts at the federal level

At the current growth rate, by 2025, urban areas will occupy over 138,000 acres of St. Tammany, or 19% of the parish. Penland et al. [16] state that by 2025,



206,000 acres or 28.6% of the parish will be urbanized. If the current trend continues, a large portion of this development will replace wetlands. Despite the recent education about the importance of wetlands, poor development practices continue to encroach on them at an alarming rate. The federal government enacted laws in the 60’s and 70’s (National Environmental Protection Act, 1969; Clean Water Act, 1972) to maintain environments like wetland habitats. The Clean Water Act protects all waters of the state, including wetlands, from pollution. Section 404 of this act provides a regulatory process for dredging or filling in wetlands. Most farming practices are allowed in wetlands without the penalty of mitigation, as long as the hydrology is not altered. The Swampbuster section of the Farm Bill does give incentives to those farmers that do not clear wetlands, but clearing is allowed. The US Army Corps of Engineers, the governmental agency responsible for permitting wetland removal, allows the filling and draining of wetlands of less than one acre without a major permit. These practices clearly do not control the removal of wetland flora or fauna. The EPA reports that, since 1979, the Corps of Engineers have been petitioned for approximately 150,000 permits to fill wetlands. During this time, only 11 were denied [17].

5.2 Comprehensive planning and smart growth

The new comprehensive plan of St. Tammany Parish [18] shows an awareness of existing inefficiencies in planning coordination. This plan aims for a more comprehensive approach to land development throughout the parish. Elements of the plan include approaches to Critical and Sensitive Habitats, such as wetlands, and Natural Hazards, including flooding. The parish intends this plan to bridge the gap between land use, transportation, housing and protection of critical areas. Another goal of the plan encourages the use of sustainable development, or smart growth principles for future growth. The term “smart growth” is increasingly used to characterize tools to facilitate sustainable development. As an example, the plan promotes Planned Units Developments (PUD’s) that protect critical and sensitive habitats by increasing density on the total site. This approach tends to enable urban growth while protecting wetlands and other sensitive habitats. The parish and the municipalities are realizing the challenges associated with sprawling growth and are starting to work together in a more holistic manner. Other smart growth incentives are needed to promote sustainable development. McElfich [19] explains that with wetland ordinances, local governments can require storm water plans or flood plain management to protect wetlands from runoff and non-point pollution. The challenge for St. Tammany Parish is to develop and implement smart tools for growing in a more sustainable, comprehensive and coordinated way.

6 Conclusion

Coastal erosion and unsustainable growth habits are destroying Louisiana’s wetlands. With the use of GIS and remote sensing imagery and analysis, we have



shown that urban sprawl is turning Louisiana’s wetlands into cookie cutter subdivisions. Partition of governance, lack of strong federal policy guidance, and pressure of development have created a fragmented landscape of isolated communities and unlinked pieces of natural habitats. In recent years, planners and environmentalists have recognized that Smart Growth tools can lead to a more sustainable development for current and future communities. Nevertheless, while St. Tammany Parish seems to be headed towards implementing a more orderly and efficient future pattern of urban expansion, pressure from growth is constant. A real awareness and coordination have to exist at all the different levels of governance for sustainable planning policies to have success.

References

[1] Barras, J.A., Beville, S., et al, Historical and Projected Coastal Louisiana Land Changes: 1978-2050: USGS Open File Report 03-334, 2003.

[2] Louisiana 2000 Summary Population and Housing Characteristics; US Census Bureau Web Site. (Coastal parish population total was calculated based on the sum of the populations of the 20 coastal parishes: Ascension, Assumption, Calcasieu, Cameron, Iberia, Jefferson, Lafourche, Livingston, Orleans, Plaquemines, St. Bernard, St. Charles, St. James, St. John the Baptist, St. Martin, St. Mary, St. Tammany, Tangipahoa, Terrebonne, and Vermilion). http://www.census.gov/prod/cen2000/phc-1-20.pdf.

[3] Malpezzi, S., Estimates of the Measurements and Determinants of Urban Sprawl in US Metropolitian Areas. Center for Urban Land Economics Research, University of Wisconsin: Madison, 1999.

[4] Ewing, P., et al, Measuring Sprawl and Its Impacts; Smart Growth America, www.smartgrowthamerica.org/sprawlindex/sprawlindex.html

[5] Gordon, P., & Richardson, H., Are compact Cities a Desirable Planning Goal? Journal of the American Planning Association, Winter, p. 99-105, 1997.

[6] Galster, G., Hanson, R., et al., Wrestling Sprawl to the Ground: Defining and Measuring an Elusive Concept, Fannie Mae Foundation: Washington, D.C., 2000.

[7] Harvey, R.O. & Clark, W.A.V., The Nature of Economics and Sprawl, Land Economics, 41 (1), 1965

[8] Downs, A., New Visions for Metropolitian America. Brooking Institution: Washington, D.C., 1994.

[9] Ehrenfeld, J.G., Evaluating wetlands within an urban context, Urban Ecosystems, January 2000,vol.4, no.1, p.69-85.

[10] United States Environmental Protection Agency (USEPA). Clean Water Act Website, Washington, D.C., http://www.epa.gov/region5/water/cwa. htm.

[11] General Accounting Office. [12] National Research Council.



[13] Lake Ponchartrain Basin Foundation Website. Habitat Change in St. Tammany Parish; New Orleans, www.saveourlake.org.

[14] Malpezzi, S., & Guo, W.K., Measuring “Sprawl:” Alternative Measures of Urban Form in U.S. Metropolitian Areas. Center for Urban Land Economics Research, University of Wisconsin: Madison, 2001.

[15] Hess, G.R., Salinda, S.D., et al. Just What is Sprawl Anyway?, unpublished paper, North Carolina Forestry Department: Raleigh, www4.ncsu.edu:8083/~grhess/papers/sprawl.pdf.

[16] Penland, S., D. Maygarden, et al. Environmental Atlas of Lake Pontchartrain, United States Geologic Survey: New Orleans, 2002.

[17] Understanding the Clean Water Act Website; River Network, Portland, http://www.cleanwateract.org/Pages/c7.htm.

[18] St. Tammany Parish, New Directions 2025, Land Use Plan, 2001. [19] McElfich, Jr., J. M. Nature Friendly Ordinances: Local Measures to

Conserve Biodiversity, Environmental Law Institute: Washington, D.C., 2004.



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