I've written a few blogs previously that describe the impacts of COVID-19 and border closures on population growth and change.
The situation continues to evolve and the impacts differ by location.
By far the most impactful measure implemented is the closure of the international border.
This has effectively cut off the major source of population growth - net overseas migration (NOM).
In 2018-19, NOM accounted for 62% of population growth in Australia.
So yes - Australia's population will grow without overseas migration, but there are significant differences between the state capitals and regional areas.
This blog takes a scenario approach and looks at the impact on population change that occurred in 2018-19 had there been no overseas migration.
The closure of the international border
In March 2020, Australia's international border was closed to non-citizens, and Australian citizens and permanent residents were encouraged to come "home".
Furthermore, Australians were banned from leaving the country except in permitted circumstances.
The effect on international movements was immediate - ABS data released since that time shows that arrivals have slowed to a mere trickle when compared to previous years.
In fact, the number of permanent and long term departures now exceeds permanent and long term arrivals.
In the June 2020 quarter there were 10,880 departures and 8,120 arrivals.
This compares with 170,750 arrivals and 128,370 departures in the same quarter in 2019.
It's likely that people departing are temporary visa holders who aren't eligible for financial support such as JobKeeper.
The impacts of the border closure are ongoing.
As I write this blog in late October 2020, international arrivals are few and far between.
International aircraft movements in and out of Australia are limited.
Qantas has cancelled most of its international routes and does not expect them to restart until mid-2021.
The Commonwealth Treasury has forecast negative NOM for 2020-21, ie more people leaving the country than arriving - a rare occurrence in Australian history.
However there are signs of life.
Some international students have been allowed back into the country, but only in selected locations such as Darwin.
A travel "bubble" with New Zealand was established, albeit one way.
Within Australia, state border restrictions continue to be relaxed as COVID case numbers remain low.
A "No NOM" scenario
The ABS has published data on the components of population change as part of the annual regional population release for the last three years.
The balance between the components determines the volume and rate of population growth. 
It's important to note that the components are not always positive, eg if there are more deaths than births in a region.
Without NOM, places can still grow if natural increase and/or internal migration is sufficiently high enough to counterbalance overseas migration.
This analysis uses the 2018-19 ERP to look at the impact of population growth in the absence of NOM - a "No NOM scenario".
To simplify matters, NOM is assumed to be zero in all areas, which means that population change can only occur via internal migration or natural increase.
In reality NOM is unlikely to be zero in 2019-20, as the border closure did not occur until March, ie three-quarters of the way through the financial year.
In the absence of NOM, housing and employment markets would change, and this would in turn would influence patterns of internal migration.
This analysis is merely an examination of the impacts that would have occurred if there was no NOM in 2018-19, using the previously published figures.
As noted above, the Commonwealth Treasury has forecast negative NOM for 2020-21, so this analysis will provide an indication as to which areas will be most impacted.
Rapid growth is tempered with no NOM
In a No NOM scenario, Australia's population would have continued to grow simply because there are more births than deaths ie natural increase.
The population growth rate in 2018-19 as published by the ABS was 1.5%, or 382,880 persons. 
Without NOM, the growth rate is more than halved (0.6%) and the volume equates to the level of natural increase ie 143,280.
Most states and territories record modest growth, and Queensland becomes the fastest growing state (1.1%).
This is due to the higher volume of net interstate migration which is a long standing feature of population growth in that state.
NSW and Victoria are most impacted in a No NOM scenario, with growth rates of 0.3% and 0.8% respectively.
At the local level, the results of the No NOM scenario are more pronounced.
The table below shows the fastest growing LGAs in 2018-19, and then compares the population and growth rate under a No NOM scenario.
In 2018-19, Camden, located in Sydney's outer south-west, recorded the strongest growth rate across Australia (7.9%), which equated to around 7,410 persons.
The main driver of this growth was internal migration, which accounted for three-quarters of the volume.
NOM accounted for just 4% of growth, or 304 persons.
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As a result, Camden's population growth is not greatly impacted in the No NOM scenario, and it remains the LGA with the strongest growth in a No NOM scenario - albeit with a slightly lower growth rate of 7.6%.
In contrast, Wyndham, on Melbourne's western edge, recorded a growth rate of 5.9% in 2018-19 (15,120 persons).
This has been one of the strongest growing LGAs in the country for several years.
The drivers of growth are different to Camden - internal migration still accounts for the largest share (42%), but NOM contributed to 31% of total growth in 2018-19.
As a result, Wyndham's growth rate is quite different in the No NOM scenario, recording 4.1% or more 10,000 persons.
Growth on this scale is still significant enough to create planning issues and put pressure on community services, education facilities and transport infrastructure.
Most of the LGAs on this list still record strong growth in the No NOM scenario due to relatively high levels of natural increase and/or internal migration.
But there are several where population growth is effectively reduced to zero, or there is negative growth.
These are primarily inner city regions where the driver of growth is NOM, particularly international students.
For instance, the City of Melbourne grew by 5.1% in 2018-19, including NOM of 8,600 persons.
Without NOM, the volume of growth falls to just 41 persons (0.0%) and remains positive only because natural increase slightly exceeds the loss recorded through internal migration.
The City of Melbourne also appears in the table below, which shows the LGAs that are most impacted in a No NOM scenario.
These LGAs are effectively those with the highest volume of NOM contributing to population growth in 2018-19.
The list is headed by Brisbane City Council, but this is largely on account of its large population size.
NOM contributed 58% of the total volume of population growth in 2018-19.
Under a No NOM scenario Brisbane continues to grow - albeit at half the rate - as internal migration and natural increase are also strong contributors to population change.
Other LGAs that are impacted the most record a loss of population through internal migration, so when NOM is taken out of the equation the overall impact is a decline in population.
This is particularly evident in Cumberland Council, which records a growth rate of -2.0% in a no NOM scenario - a difference of 4.1 percentage points compared to its official 2018-19 growth rate.
Many of the LGAs with this characteristic also tend to be located near major university campuses in suburban locations, such as Parramatta (-0.2% growth in a No NOM scenario), Monash (-1.8%) and Randwick (-1.7%).
This was foreshadowed in one of my previous blogs that looked that at the residential location of international students.
Other LGAs on this list are on the urban fringe, with greenfield development sites that attract young families.
As a result, they grow via natural increase and internal migration, as well as NOM.
In a No Nom scenario, their growth rates are tempered (such as the example of Wyndham discussed above).
Casey Council - also located in Melbourne - is another example, recording a growth rate of 2.8% in a No NOM scenario.
What areas are not affected in a No NOM scenario?
In 2018-19, just under one-third of Australia's LGAs recorded negative population growth.
This was headed by Northampton Shire, located on Western Australia's Batavia Coast, where the loss of population was -4.3%, or 133 persons.
This was driven by net internal migration loss ie people moving out of the LGA.
The population in 2019 was just 2,944 persons.
Many LGAs that recorded negative population growth in 2018-19 had small populations and were located in rural and remote regions, particularly in Western Australia.
Internal migration loss drove population change in these LGAs, and the contribution from NOM was minimal.
As such, the irony is that many of these LGAs with long standing trends of population loss are not impacted in a No NOM scenario.
They are likely to continue to record population decline, but will be joined by the LGAs in metropolitan areas as described above.
Concluding comments
This blog has looked at the impacts of a No NOM scenario on population growth in Australia ie no overseas migration.
Australia's population does continue to grow in the absence of NOM, but is driven solely by natural increase.
The situation is more diverse at the local level.
In many LGAs, the No NOM scenario results in a lower rate of population growth, and in other cases population growth becomes population decline.
The scale of impact depends on the volume and contribution of NOM to overall population change.
Australia's fastest growing LGA, Camden, retains this title in a No NOM scenario, as the contribution of NOM to growth is relatively small.
This contrasts with Cumberland Council, where a high volume of internal migration loss is compounded in a No NOM scenario to produce a growth rate of -2.0%.
A No NOM scenario is one way of looking at impacts of COVID influenced population trends, but it should be noted that no overseas migration is not a panacea for solving urban and regional planning challenges.
If anything the analysis presented here shows that some areas with high growth rates in 2018-19 continue to do so in a No NOM scenario.
The challenges presented by rapid growth are just as pressing but are complicated by negative growth in other parts of the metropolitan area.
In addition, rural areas with long standing trends of population decline are not impacted in a No NOM scenario, so the challenges associated with this remain.
