Embed Size (px)
DESCRIPTION
Low-Density Urbanization and Southern California Critical Habitats. Steven Guerry UP206a Final Project Winter 2011. Planning Issue. With respect to Southern California habitats critical to the survival of threatened and endangered species, where is it most urgent to set limits on growth?. - PowerPoint PPT Presentation
Citation preview
Low-Density Urbanization and Southern California Critical Habitats
Steven GuerryUP206a
Final ProjectWinter 2011
Planning IssueWith respect to Southern California habitats critical to
the survival of threatened and endangered species, where is it most urgent to set limits on growth?
Introduction to Region of Analysis
General Trends
County Populations (2008)
02,000,0004,000,0006,000,0008,000,000
10,000,000
Total Population: 22,423,000
Density (Pop./Sq. Mi.)
Orange
Los Ang
eles
San Dieg
o
Ventur
a
Riversi
de
Santa
Barbara
San Bern
ardino Kern
San Luis
Obispo
Imperi
al0
1,000
2,000
3,000
4,000
Region Density: 397
Projected Population Growth 2010-2015
Impe
rial
Riverside
Kern
Orange
San Dieg
o
Ventur
a
South
ern Cali
fornia
Santa
Barbara
San Luis
Obispo
San Bern
ardino
Los Ang
eles
0%2%4%6%8%
10%12%
Regional Average: 5.99%
While population is greatest on the coast, the largest projected growth rates are more inland.
Urbanized Areas and Critical Habitat
LA Metro: A Closer Look
Population Density & Total Population
Neither reveal the full impact of low-density development• Density shows no impact near critical habitats• Population shows no pattern at all
Developing an Indicator of Low-Density Impact
Why focus on low-density residential buildings?
• Low-density housing by definition requires more land
Low-density rural home development is the fastest-growing form of land use in the United States since 1950.*
Developed with the automobile in mind, low-density residential housing requires land-intensive automobile infrastructure like roads and parking
Attracts low-density commercial development
* http://www.esajournals.org/doi/full/10.1890/05-5221
Many native species have reduced survival and reproduction near homes*
• Recent trends suggest people are moving to rural areas to live in low-density housing
Exurban development has a large potential to alter biodiversity*
• Residential development poses a significant threat to native biodiversity
Mapping Definitions and MetricsUrbanization and Growth (Source: U.S. Census Bureau)• Areas categorized as “urbanized” in 2000• Population Density in 2000• Projected Total Population Growth for 2010 and 2015
Low-Density (Source: U.S. Census Bureau)• Percentage of housing composed of detached single-unit
structures will serve as a proxy of overall low-density development.
Critical Habitats (U.S. Department of Fish and Wildlife)• Areas the Endangered Species Act deems “(I) essential to the conservation of the
species and (II) which may require special management considerations or protection” for species classified as “Endangered” or “Threatened”.
Aggregate #1
Method
PurposeTo show where low-density development is most intense
Total Population of Census Tract
multiplied by
Percentage of housing categorized as “occupied structure with 1-unit detached”
Aggregate #2: Projecting Growth
Methodology• Based on Census estimates for 2010 and 2015
Purpose• Show where the greatest level of low-density development is expected.
• Exclusion: Census tracts that underwent (a) negative population growth AND (b) percentage of low-density housing decreased
Total Population Increase multiplied by Percent Increase of “occupied structure with 1-unit detached”
But the areas in red are largely uninhabited.
Isolate the Areas of Low-Density Growth in Existing Urbanized Areas
Areas of Growth within 1-mile of Critical Habitats Over-layed on Urbanized Areas
Where is it most urgent to set limits on growth?
1. Within 1 mile of a critical habitat2. Designated as urbanized by 2000 Census3. Exhibits greatest trend of land intensive (low-density) growth
* http://www.esajournals.org/doi/full/10.1890/05-5221
Why limit growth and not just promote density?
Case Study:
Hemet
Walmart
GIS Skills• Inset• Aggregating attribute fields• Attribute sub-selections
o Urban areas map was created by selecting areas classified as “urban” (U) from a map featuring both urban and rural areas.
• Boundary sub-set selectionso Urban areas map further trimmed to only include urbanization within five miles of
critical habitats.• Distance
o Buffering Extracting Information from a buffer
• Geoprocessingo Dissolved all Census Tracts in CA into a 10-county “Southern California” regiono Upper two quantiles from aggregate #2 clipped by urban areas
• Charts• Elevation• Google Mash-up
