Water Resource Development Commission Population Working Group Population Projections 2010, 2035, 2060, 2110 December 10, 2010
Our Challenge “There are known knowns…there are known unknowns…But there are also unknown unknowns…things we don’t know we don’t know.” Former Secretary of Defense Donald Rumsfeld
Meetings October 15 October 26 Sent email (10/27 /10) to County Planning Departments soliciting input November 9 November 22
Projection Development Various levels of geography Based on published projections and existing data Adjusted for economic downturn Three scenarios; Low, Mid, High Disaggregated to geographies using political boundaries and basin boundaries Some data was not included but is very important for consideration in the WRDC process (“bin”)
Projection Geography State County Basin County-Basin portions Basin-County portions CCD, CDP, MPA, Incorporated Area
Data Sources DES Projections from 2006 MAG Projections by MPA Projections by Incorporated Area for Gila, Pima and Pinal Counties US Census Bureau, “Methodology and Assumptions for the Population Projections of the United States: 1999 to 2100
Scenarios Original DES state projection reduced for the economic downturn US Census projections to 2100 used to extend state projections to 2110 US Census projection scenarios used to develop three State scenarios
Likely Outcomes Bracketed Between High and Low Series Projections
Disaggregation to Political Boundaries Each original data source extended to 2110 using proportional relationships County proportion of state CCD, MPA or Incorporated Area proportion of County CDP proportion of CCD For years 2056 – 2110, the 2055 proportion held constant Produced projections down to the CDP, CCD Remainder, MPA, Incorporated Area and Balance of County in each year, for each scenario from 2010 through 2110 EXAMPLE: County A proportion of State in year X multiplied by State projection in year X = County A population for that year.
Disaggregation to Basin Boundaries Political boundaries disaggregated into groundwater basins using GIS La Paz, Pima and Pinal Counties provided feedback Data reviewed to ensure that portions added up to 100%
Database ACCESS database created Original projection data Proportion of each political boundary and basin Queries allow ease of data extraction County Basin County-basin portions Basin-county portions
"Bin" Items 2056-2110 projections not model based New demographic model projections for Arizona available in 2012 Regional assessment studies were not incorporated US Census counts may be underreporting Indian Tribe populations Development on State Lands adds layer of complexity Not all County Planning departments had time to offer input WRDC projections may not match other local and regional studies
Demographer Humor “…in the Inferno of Dante’s Divine Comedy, there is a special place in the Eighth Circle of Hell reserved for those who presume to peer too far into the future. Their punishment, for all eternity, is to have their heads permanently pivoted 180 degrees to the rear…” Michael S. Teitelbaum, Department of Economic and Social Affairs, Population Division, United Nations
“Final” report and description of methodology will be forthcoming Questions?