Population Projections at the District
Corey C. Denninger, GISP
Senior GIS Analyst
Objectives
• History of Population Projections at the District
• Methodology Overview
• Deliverables
• Data usage
• Examples
History of Population Projections at the District
• Pre-2005 methodology = ‘Percent Shares’
– Calculate area of county
– Calculate area of utility (if known)
– Calculate utility area percentage of county
– Apply utility percentage to BEBR county-
wide projection
History of Population Projections at the District
• Example:
– County total area = 100,000 acres
– Utility X total area = 30,000 acres
– Utility X area percent of county = 30%
– BEBR 2030 population projection = 400,000
– Utility X 2030 population projection =
120,000
History of Population Projections at the District
• Issues with this methodology?– Does not consider numerous factors:
• Only at the county level (and some munis)
• Build-Out/Densities
• Conservation areas
• Future Land Use
• Existing Land Use
• Distance to roads
• DRIs/PUDs
• Historic Census Data
• Other boundary constraints (e.g. political)
History of Population Projections at the District
• District RFP in 2000
• Enters into contract with Ayers shortly
thereafter
• Issue, cause District to terminate the
contract in 2003
• District RFP in 2003, approved GISA
• First District-wide deliverables in
2006/2007
Methodology Overview
• GIS-based small area population estimates and projections
• Uses 2010 U.S. Census population cohort at the tract level as
starting point
• Calculates growth trends at the Census tract level
• Historic densities applied to appropriate land uses types
• Spatially distributes (or ‘disaggregates’) to the parcel-level
• Normalizes to BEBR (Bureau of Economic and Business Research)
county-level population estimates and projections
• Constrained by build-out estimates
Methodology Overview• Model considers
– Growth Drivers:
• Distance to roads
• Existing infrastructure
• Interchanges
• Commercial Land
• Waters
• Large developments (DRIs, PUDs)
– Future land use
– Existing land use
– Wetlands
– Conservation areas
– Historic Growth Trends
– Countywide Build-out
– U.S. Census data (including tract persons per household (pph))
– SWFMWD seasonal methodology
Methodology Overview
• Estimates previous year pop and projects future pop every 5 years to 2040
• Population Cohorts included:– Permanent (POP14)
– Peak Seasonal (POP14_P)
– Functionalized Seasonal (PERMSEAS14)
– Functionalized Tourist (POP14_T)
– Functionalized Net Commuter (POP14_NC)
– Total Functionalized* (TOTFUNC_14)
* PERMSEASyy + POPyy_T + positive POPyy_NC
Methodology Overview
• District model inputs:
– PS_SERVICEAREAS layer (annually)
– Lodging Facilities layer (annually)
– FLU layers District-wide (annually)
– Projections of Lodging Rooms - tabular (annually)
– Census Variables layer (decennial - once every 10 years)
Deliverables
• 18 feature classes and 1 Excel table
– 1 PS_SERVICEAREAS population fc
– 16 parcel-based countywide population fc’s
– 1 parcel-based Lee county population for areas permitted by
SWFWMD
– 1 Excel file with county and public supply service areas
summarized in tabular format (including DSS or non-served
areas)
– 2 pdf documents: Methodology and Updates
Data Usage
• Water Supply Planning & Forecasting
• Water Use Permitting
• Percent Shares (various jurisdictions)
• Total Pop (Finance Bureau)
• Potential Population Impacts (flooding due to storms or dam breeches)
• Total pop and demographics (COM)
• External requests
• Other ad-hoc
Examples
• Feature classes (poly’s and points)
• PSSA Population tables
• Percent Shares
One Parcel Example
Thank you!
Questions?
http://www.swfwmd.state.fl.us/data/demographics/
Credits:
• GIS Associates, Inc.,
• Bureau of Economic and Business Research
• U.S. Census Bureau