Title: Vegetation and Population Density in Urban and Suburban Areas in the U.S.A.
1Vegetation and Population Density in Urban and
Suburban Areas in the U.S.A.
- Francesca Pozzi
- Center for International Earth Science
Information Network - Columbia University
- New York, USA
- Christopher Small
- Lamont-Doherty Earth Observatory
- Columbia University
- New York, USA
Istanbul, 11-13 June 2002
2Objectives
- Characterize urban areas based on demographic and
physical characteristics - Population Density
- Vegetation Abundance
- Examine consistency of relationship between the
two variables in the USA - Compare with existing land cover classification
(USGS) - Can this help us find alternative classification
systems for urban areas?
3Case Study The USA
- 6 cities with different geographic location,
physical environment and urban growth dynamics
Atlanta Chicago Los Angeles New
York Phoenix Seattle
4Data Population Density
- 1990 US Census Bureau population counts at the
block level (Spatial and tabular data) - Density in people/km2
- Data reprojected to UTM,
- Rasterized to 30 m,
- Co-registred to Landsat
New York City
5Data Vegetation Abundance
- Landsat TM data, circa 1990
- Spectral reflectance of many urban areas can be
described as linear mixing of - Low albedo
- High albedo
- Vegetation
- Linear un-mixing
- Fraction images showing areal of each endmember
within each pixel (0 to 1) - Validation with IKONOS, accuracy within 10
Vegetation Fraction (White 0, Dark Green 1)
6Data USGS National Land Cover Dataset
- Based on Landsat TM data
- Nominal-1992 acquisitions
- Modified Anderson LULC Classification System
- Selected 3 Developed classes
- Low Intensity Residential
- High Intensity Residential
- Commercial/Industrial/Transportation
USGS NLCD Developed classes (Light orange
LIR, Orange HIR, Red CIT)
7Analysis
- Analysis of population distributions across the
entire U.S. - Demographic Classification
- Quantification of the relationship between
population density and vegetation fraction - Bivariate distributions
- Marginal distributions
- Comparison with USGS NLCD Classes
- Distributions of areal extent of each USGS class
as a function of population density and
vegetation fraction
8Population Density Distribution in the U.S.
- Multimodal Distribution
- Modes are
- Rural pop. dens. lt100
- Suburban 100 ltpop.dens. lt 10,000
- Urban pop. dens gt10,000
- people/km2
- Grey line Western US (west of the 90 W)
- Black line Eastern US
9Geographic Distribution of U.S. Population
10Demographic Classification
Population Density
Example portion of Chicago
3 Classes of population density ? Demographic
Classification Overlay with vegetation
fraction Blue Rural Green Suburban Red Urban
Demographic Classification
Vegetation Fraction
11Bivariate Distributions
Distributions of people as functions of
Population Density and Vegetation
Fraction Legend warmer colors higher numbers
of people on Log scale
12Marginal Distributions
13Comparison with USGS NLCD Classes
- Distributions of areal extent of each USGS
Developed class as functions of population
density and vegetation fraction - Red High Intensity Residential
- Green Low Intensity Residential
- Blue Commercial/Industrial/Transportation
14Comparison with USGS NLCD Classes
- Visual comparison between Demographic
Classification and USGS NLCD Developed Classes - Legend
- Blue Rural/CIT
- Green Suburban/LIR
- Red Urban/HIR
- Cities
- Top Chicago
- Middle New York
- Bottom Los Angeles
15Conclusions
- Population density distribution in the U.S.
?demographic classification (urban/suburban/rural)
- Vegetation cover is the most consistent spectral
characteristics in suburban areas - Spectral heterogeneity ? wide range of vegetation
fractions in demographically urban and suburban
areas - Not possible to consistently characterize urban
and suburban areas in the U.S. based on
reflectance characteristics at Landsat
resolutions
16What next?
- Emphasize results on quantitative
characterization of vegetation abundance as means
to provide physical basis for comparison of urban
environments - Explore classification schemes based on spectral
heterogeneity at multiple pixel scales,
supplemented by auxiliary data sources - Demographic Classification for the year 2000 and
urban sprawl analysis
17Thank you!
- fpozzi_at_ciesin.columbia.edu
- http//sedac.ciesin.columbia.edu/urban_rs