Land Use Class Notes September

RFP for:
Update of a 1992 Comp Plan for county in the Sun Belt: e.g. Prima County, AZ.
• Look at population projections
• Look at the population methods
o Look out for
• 1990 census to project 2010 cohort survival analysis
• cohort survival, look at the likelihood of survival of age groups and derive your population pyramids
 doesn’t take into account migration
• old people are moving there
• Mexicans
 Focuses mostly on women’s fertility is 2.1 kids
• Rate of Growth in U.S. from 1990 to 2000 was 13.2% or a little more than 1.1%/year
• US and Canada are the fastest growing populations in the industrialized world
o Look out for a trend line analysis
• 1970, 1980, 1990 → extrapolate from there
• in-migration is key to taking apart the exponential trend analysis
• Policy Based Method
o Takes into account land use availability
• Doubt they used it
What would our strategy be?
• Design based
• Location
• Carrying Capacity
• Estimated population
o American community survey
o School enrollment
o Housing permits
o Public Utility Co → addresses, households
• Assumptions to project to 2030
o Immigration/out migration
o Land use
o Economic activity
o Aging pop
o Climate
o Scenarios/alternatives: the good, the bad, and the ugly/high, low, medium.
• Does population just happen? Or can you use the comp plan or the projection to control


What is Your Vision

• And how does the current size and diversity and age of your pop fit that vision?
• And how many people do you want and what type in 20 years?
• What is the optimal population?
  
• A number of communities will reach build out in our lifetime.
  
• county can buy land
• make growth boundaries
  

Population current levels and future projections

• The hear ot fht Comp Plan Process
• Key for land use and other

**MAKE CONNECTION BETWEEN POPULATION GROWTH AND LAND CONSUMPTION (for paper)

Population Projection Methods

• Something to consider: are you trying to come up with a single population number for a certain future date?
• Are you looking at a range of possibilities ans selecting the most likely population change scenario?
  

Methods

• Simple extrapoalation of population trend
• linear extrapolation: oppulation will change by the same number of people in each future year as the averagae annual change during the previous
• linear extrapolation ain't good

• Actual population change vs. projected
• risk and uncertainty: catastrophic events
• faster growing communities have larger estimate errors
• larger pop have smaller errors
• the more migration is a factor, the greater errors are likely to be listed above
• the farther you go out in time the greater the errors of your projections

More methods

• complex extrapolation: regression, times series data
  
• structural models: Impact of employment growth, household size, land use
  
• note: simple population projection methods can be just as accurate as complex methods
  

Range of Forecasts and Implication sfor Land Use

• 1%,2%, 3% growth rates over 20 years: and the Rule of 70 (in 10 years your pop will double if you grow at ten percent)
  
• if your pop grows at 5% for 20 years
• Dominant development form: urban suburban infill and limited expansion, new villages, sprawl
• Water quality impact: impervious surface and on-site septics-water supply
• land consumption
• infrastructure costs
• when build-out will be reached