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Operational issues – meshblock maintenance

This chapter explains the process, and outlines the rules and guidelines, for making changes to meshblocks.

The real world is constantly changing: the Earth’s features are constantly moving, population and mobility increases, buildings are constructed and demolished, and land use changes. Statistics NZ maintains meshblocks to reflect the changes on the ground. However, since changes cannot be implemented immediately, there will always be a discrepancy between the real world and the most recent version of the classification.

A number of electoral and administrative geographies are legally required to align with meshblocks. This can result in high priority meshblock boundary adjustment requests from sources outside Statistics NZ. These requests can sometimes conflict with requirements of the standard, such as when a meshblock population change breaches the range defined in this standard. A balance between competing needs can be negotiated.

Users of meshblock and other geographic boundaries require access to up-to-date digital boundaries. The boundaries are required before any statistics are made available. In particular, local government requires new digital boundaries to reflect changes that have been made during local government boundary representation reviews.

Changes to the meshblock digital boundary and classification are made throughout the year. A major release is made at 1 January each year with ad hoc releases available to users at other times.

Versioning of meshblocks enables ‘major releases’ for statistical output requirements and ‘minor releases’ for internal administrative purposes, or to meet external non-statistical requirements. All versions are released with accompanying metadata.

Splitting, nudging, and amalgamating meshblocks

Meshblocks are maintained by splitting, nudging, and amalgamating their boundaries to ensure they are relevant for their purpose and continue to meet the standard.

The following is the process to be followed when a need for change has been identified or requested.

A need for change is identified or a change request is received

A need for a meshblock change is identified internally or a meshblock change request is received from an external source.

Reasons for meshblock changes can include:

  • real world changes resulting in one or more meshblock criteria being violated
  • Statistics NZ requests for boundary changes so that statistical geographic boundaries can be moved
  • external requests for boundary changes so that legal or administrative boundaries can be moved
  • to improve meshblock categorisation within the land/water demarcation classification
  • to improve the population size balance of meshblocks in areas of population change
  • to maintain alignment to cadastre and other geographic features.

To accommodate requests, Statistics NZ considers how the proposed change will affect the meshblock criteria listed in Meshblock requirements including legally defined boundaries and the impact on statistical requirements. Unless there is a significant reason for doing so, a meshblock will not be changed if the change will create one or more meshblocks that violate the requirements of a meshblock.

The type of meshblock change is determined (split, nudge, or amalgamation)

A split is where an existing meshblock is divided into two or more meshblocks. This occurs when a meshblock significantly exceeds the optimal size (see Meshblock requirements). Splitting of meshblocks can occur at any time.

A nudge of a meshblock boundary involves the shifting of a boundary common to two or more meshblocks. Nudging can occur at any time, however nudging of meshblock boundaries that are coterminous (that is, have the same border or cover the same area) with administrative or electoral boundaries can only be undertaken when these boundaries are under review.

(See Determine whether proposed changes will violate any meshblock requirements or alignment to other boundaries and Implement change in system.)

Nudging is undertaken where the splitting of a meshblock would create a small irrational meshblock or where the outcome of the nudge has little or no statistical significance. It is preferable that the area being nudged does not contain people, dwellings, or businesses.

The impact on the meshblocks affected by the nudge should generally not result in a variation of the population or employee count in businesses of more than 10 percent, or more than five dwellings. Cases where such variation is exceeded may be further considered due to circumstances such as very low population meshblocks.

The estimated area of land in the meshblock being nudged will vary according to the nature (urban or rural) of the land. Preferably nudges should not exceed the following maximum areas:

  • urban – five hectares
  • rural (excluding high country) – 20 hectares
  • rural (high country)/water areas – 50 hectares.

However, in some instances it may be more practical to implement a larger nudge than it is to create a meshblock of nil or small residential or business population.

Amalgamation of meshblocks is permitted only once every five years (prior to a census), where small, statistically insignificant meshblocks exist. The following general rules apply.

  • The meshblock must be stable with no or minimal population or economic activity change over the past two census periods.
  • Meshblocks must contain zero or near-zero ‘usually resident’ population.
  • Meshblocks should contain no major economic activity.
  • The boundary to be removed through the amalgamation of meshblocks must not be a statistical or administrative boundary. See Summary of nudge and amalgamation rules and guidelines for exceptions to this rule.
  • Meshblocks to be amalgamated should have the same urban rural classification.

Determine whether proposed changes will violate any meshblock requirements or alignment to other boundaries

Under sections 19T(b), 19U(b), and 19W(c) of the Local Electoral Act 2001, all ward, constituency, community board, local board, and territorial authority subdivision boundaries (including those of Māori wards or constituencies) must coincide with the boundaries of meshblocks determined by Statistics NZ and used for parliamentary electoral purposes.

Nudges to boundaries cannot be made where a boundary is coterminous with an electoral (general electoral district and Māori electoral district), regional council (including constituency and Māori constituency), or territorial authority (including community board, local board, ward, and territorial authority subdivision) boundary. Exceptions to this rule only occur when representation reviews for local government and parliamentary elections are being undertaken at the same time and it is known that both boundaries will change. At this time boundary changes are negotiated to ensure they meet all needs (statistical and electoral/administrative) as much as possible.

Nudges to boundaries that are coterminous with statistical geographies or urban rural areas, or are coterminous with administrative boundaries, may only proceed after consultation and agreement has been obtained from the appropriate parties when dwellings, or residential or business populations are affected. The reverse process is also possible. After consultation, changes to electoral/territorial authority boundaries may result in meshblock boundaries being nudged.

If a local authority wishes to develop community board, local board, territorial authority subdivision, ward, Māori ward, constituency, or Māori constituency boundaries that do not align with meshblock boundaries, they will need to consult Statistics NZ to determine whether specific meshblock boundary alterations are possible.

Implement change in system

Meshblock changes that meet the criteria outlined above are carried out using the meshblock edit tool in the Geospatial Management System within ArcGIS.

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Summary of nudge and amalgamation rules and guidelines

Boundaries that can be nudged to align non-cadastral to cadastral boundaries where no dwelling or population is affected:

  • area unit
  • urban/rural area.

Boundaries that can only be nudged during representation reviews:

  • territorial authority
  • ward
  • Māori ward
  • community board
  • local board
  • territorial authority subdivision
  • regional council
  • constituency
  • Māori constituency
  • district health board.

Boundaries that can only be nudged when requested by the Representation Commission:

  • general electoral district
  • Māori electoral district.

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