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Monitoring changes in the population and communities of Greater Christchurch post EQ – . An updated analysis. James Newell, MERA ( Monitoring and Evaluation Research Associates Ltd) September 18 th , 2012 Lunchtime Seminar.
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Monitoring changes in the population and communities of Greater Christchurch post EQ – An updated analysis James Newell, MERA (Monitoring and Evaluation Research Associates Ltd) September 18th, 2012 Lunchtime Seminar Final annotated and cleaned up “wrap up” version – includes some definitions and clarifications – edit as at 27/9/2012
Monitoring and understanding local / community population changes post - EQ • Collect and analyse the evidence base – multiple sources … • Explain / predict population / household (and residential land use) change • Provide information on the actual changes to stakeholders / interested parties • Refine recovery scenarios
Explain / predict population / household (and residential land use) change • School specific issues such as damaged buildings • Existing and use controls and changes in land use controls post – EQ (regulatory mechanisms) • Residence specific issues such as property damage’ land use damage, changes land use suitability • Greenfield residential development, intensification processes on existing stock or by making physical alteration to the existing stock • Changes in jobs, business income, job (or school) accessibility … personal economic impacts • Trauma associated with the social / psychological impact of the EQ
This seminar – statistics mainly • In two parts (with a break out for discussion and a top up of tea / sandwiches in the middle?) • Some big picture population statistics and indicators for Greater Christchurch • Some measures of Community transformations within Greater Christchurch post EQ
The big picture - statistics on trends in Greater Christchurch – before and after June 2011
Components of “usual residence” population change • Migration – Greater Christchurch long term resident arrivals and departures • External migration arrivals and departures – and effective “net” external migration • Internal migration arrivals and departures – effective “net” internal migration • Births • Deaths
Stats NZ est age structure 2006 to 2011- Greater Christchurch
International Migration (PLT) Permanent “Long Term” - arrivals, departures, net migration ..
International Migration (PLT) Effect of the EQ on international migration movements Expected vs Actual Movements
A working measure of the effect of the Christchurch EQ on international migration arrivals and departures • An estimator of “expected” migration arrivals or departures if there was no earthquake • Based on relativities between historical seasonal movements for Greater Christchurch and that for all or a large unlinked chunk of the rest of NZ • The rest of NZ defined as the North Island as a whole, as too much linkage between the rest of the SthIsl and Chch – by age, sex etc.
Actual versus “expected” International migration arrivals - Greater Christchurch
Actual versus “expected” International migration departures - Greater Christchurch
International Migration (PLT) Net Effect of the EQ on international migration movements Estimated as the net of Expected vs Actual Movements by month for any demographic group
Estimated “earthquake effect” on international arrivals and departures by month for Greater Christchurch
Estimated “earthquake effect” on international arrivals and departures – ages 0 to 4 yrs only
Estimated “earthquake effect” on international arrivals and departures – ages 5 to 14 yrs only
Estimated “earthquake effect” on international arrivals and departures – ages 15 to 19 yrs only
Estimated “earthquake effect” on international arrivals and departures – ages 20 to 24 yrs only Note that this may in part reflect a lower base of tertiary students in Christchurch to leave – not a lower rate of external migration amongst 20 to 24 year old Christchurch residents
public health organisation enrolments Observational data lagged by a month ..
NZ Post Redirections by month To / from Canterbury household/individual permanent redirections only …
Residential Building Consents by month By value …
Total residential building consents by value for Greater Christchurch
School rolls .. Note that the analysis of July 2012 roll records are not official figures – and only include some records for some schools. It includes those schools which supplied address matched returns for all of the 2010, 2011 and 2012 years only
Estimated changes in school age 2010 to 2012 resident in Greater Christchurch • Indicative results only – and are not official July 2012 estimates • Screens out schools for which stats were missing for either 2010, 2011 or 2012 • Main gaps were in the July 2011 dataset • Includes students from schools located in Greater Christchurch • Excludes any students • who were resident outside Greater Christchurch • whose address wasn’t geocoded
Total Response Ethnicity : % Change in Enrolments - years 2 to 5
Total Response Ethnicity : % Change in Enrolments - years 7 to 11
Some summary points • Net Migration loss for the June quarter and September quarter 2011 • Continues into the December 2011 and March 2012 quarters • Some recovery into the June quarter 2012 • Different patterns for different age groups, different ethnicity groups, internal – inter-regional and international arrivals / departures… etc.
Estimated changes in the number of resident school age children in the Greater Christchurch UDS by location of residence : 2010 to 2012 (indicative and not official results) Summary Tables on a Greater Christchurch UDS “geographic division” of residence basis
Assumptions / limitations : school age children 2010 to 2012 by geographic sector of residence • Indicative results only – and are not official July 2012 estimates • Screened out schools for which stats were missing for either 2010, 2011 or 2012 • Main gaps were in the July 2011 dataset • Includes students from schools located in Greater Christchurch • Excludes any students • who were resident outside Greater Christchurch • whose address wasn’t geocoded
Definition : Greater Christchurch Urban Development Strategy Geographic Division • a MERA formulated grouping that combines UDS “geographic sectors” and “urban zones” • at the minimum extra detail needed to be cross compatible to both UDS “geographic sectors” and “urban zones” • Makes life easy – so that any statistic can be aggregated to either sectors or zones as needed
GtrChch “UDS Spatial frame” • Summary Tables on a Greater Christchurch “Divisional” basis • A composite disaggregation of “Greater Christchurch” into a hybrid classification that bridges “geographic sectors” and “urban zones” • The UDS geographies are generalised to a 2006 area unit base
(Crude) Estimates of the % population living in EQ red or green TC3 zoned dwellings • Based on overlaying June 2012 EQ land zone GIS polygons (land units) over the 2006 meshblock layer • % population in any one zone type estimated as the % of the meshblock land area in any particular EQ zoning type • This crude result it seems may overestimate the % of households and population living in Green TC3 affected dwellings • Note that the EQ zone layer used dates to late June 2012 – and as a result some of the decisions on Lyttleton and the Port Hills are not incorporated – amongst others …
% Population est in Zoned Properties versus est % change in resident children Mar 2010 to Jul 2012 TC3 or Red land to population ratio too high? Explained by zoning changes since June 12?
% Population est in Zoned Properties versus est % change in resident children - Mar 2012 to Jul 2012