Trends

This section considers the impact of demographic trends, climate change, and different economic growth trends and scenarios on the demand for infrastructure.

Demographic trends[47]

Between 2006 and 2031 New Zealand's population is expected to increase by approximately 22%, from 4.185 million to 5.089 million. The following are the most significant changes:

• 62% of New Zealand’s population growth will be in the Auckland region
• Manukau City will pass Christchurch City as the second most populous territorial authority by 2031
• Queenstown-Lakes District will have the highest rate of population growth with an average annual increase of 1.9%
• almost half of New Zealand’s 73 territorial authority areas will have fewer residents in 2031 than in 2006
• the 0-44 age group stabilises and the 65 and over age group doubles, and
• the number of families in New Zealand increases by approximately 20%, with the number of households increasing by 28%.

Figure 16: Projected population by selected age-groups at 30 June 2011-2026 (2006 base)

Source: Statistics New Zealand 2006 Census and forward projections using Statistics New Zealand middle and median series

Both the population increase and the distribution of this increase will put additional pressure on existing infrastructure in some areas, particularly Auckland where population drift has already put increased pressure on Auckland's infrastructure. Some of this growth in recent years has come from urban areas smaller than 30,000 and rural areas. Over time this trend will lead to increased costs for ratepayers living outside urban areas as proportionately fewer people are taxed to pay for necessary community services.

Although the projected number of school-aged children does not change significantly, the distribution of this group does change. Given this, there will be a need for further schools to be built, particularly in the Auckland area.

The increase in the growth triangle area of Auckland, Waikato and Bay of Plenty is projected to be almost 34%, compared to an increase of about 12.7% in the South Island (an increase in population of 686,000 in the former, compared with 127,000 in the South Island).

These higher growth areas have well-developed strategies, such as Auckland's Regional Development Strategy, Christchurch's Greater Christchurch Urban Development Strategy and Bay of Plenty's SmartGrowth Plan. These strategies aim to manage where growth occurs and reduce pressures for additional infrastructure.

Figure 17: Projected population as at 30 June 2011-2031 Auckland, Waikato, Bay of Plenty and South Island (June 2006 base)

Source: Statistics New Zealand 2006 Census and forward projections using Statistics New Zealand middle and median series

These population projections are based on the Statistics New Zealand medium series. Using its high series - reflecting different assumptions of future patterns of fertility (births), mortality (deaths) and migration leading to higher population projections - New Zealand's population increases to 5.4164 million, an additional 317,700 people. Approximately half of these additional people would live in Auckland (165,200), increasing Auckland's population by an additional 8.5% to 2.0975 million.

As there is some uncertainty around projecting populations over 20 years, the table that follows shows the range of scenarios at 2031 based on the low, medium and high series.

Source: Statistics New Zealand 2006 Census and forward projections using Statistics New Zealand low, middle and median, and high series

In the longer term, the proportion of superannuitants is projected to increase significantly (from about 12% of the population to about 20%). Given that our superannuation system and public health system work on a ‘pay-go' basis, this means there will be a corresponding increase in the burden on other taxpayers. These pension and health liabilities must also be considered when contemplating the level of debt that is sustainable in future.