Is Population increase in your area possible?

[Lightspeed]

Depends on timescale Mary,

Short term to overcome a specific time limited threat the rehousing camp concept works.

For longer term, semi permanent evacuation of large populations, the WWII model is tried and tested. Remember that local councils have fairly accurate records of the housing stock in their domains, and they can marry this up easily with Census data to determine which houses are under occupied. Spare bedrooms will be quickly identified, allowing evacuees to be billeted.